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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<title>Backdrops</title>
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<!--Weave of 'Backdrops' generated by Inweb-->
<div class="breadcrumbs">
<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../compiler.html">Inform7</a></li><li><a href="index.html">if</a></li><li><a href="index.html#3">Chapter 3: Space and Time</a></li><li><b>Backdrops</b></li></ul></div>
<p class="purpose">A plugin to provide support for backdrop objects, which are present as scenery in multiple rooms at once.</p>
<ul class="toc"><li><a href="3-bck.html#SP3">&#167;3. Initialisation</a></li><li><a href="3-bck.html#SP4">&#167;4. Kinds</a></li><li><a href="3-bck.html#SP7">&#167;7. Properties</a></li><li><a href="3-bck.html#SP12">&#167;12. Everywhere</a></li><li><a href="3-bck.html#SP15">&#167;15. Model completion</a></li></ul><hr class="tocbar">
<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. </b>While we normally assume that nothing can be in more than one place at
once, backdrops are an exception. These are intended to represent widely
spread, probably background, things, such as the sky, and they placing one
inside something generates <span class="extract"><span class="extract-syntax">FOUND_IN_INF</span></span> rather than <span class="extract"><span class="extract-syntax">PARENTAGE_INF</span></span>
inferences to avoid piling up bogus inconsistencies.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="identifier-syntax">inference_family</span><span class="plain-syntax"> *</span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">; </span><span class="comment-syntax"> 56; for backdrop things in many places</span>
<span class="identifier-syntax">inference_family</span><span class="plain-syntax"> *</span><span class="identifier-syntax">FOUND_EVERYWHERE_INF</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">; </span><span class="comment-syntax"> 57; ditto</span>
<span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K_backdrop</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="identifier-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">P_scenery</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">; </span><span class="comment-syntax"> an I7 either/or property marking something as scenery</span>
<span class="identifier-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">P_absent</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">; </span><span class="comment-syntax"> an I6-only property for backdrops out of play</span>
</pre>
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">backdrop_found_in_notice</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">backdrop</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">found_in_routine_iname</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">many_places</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">CLASS_DEFINITION</span>
<span class="plain-syntax">} </span><span class="reserved-syntax">backdrop_found_in_notice</span><span class="plain-syntax">;</span>
</pre>
<ul class="endnotetexts"><li>The structure backdrop_found_in_notice is private to this section.</li></ul>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. Initialisation. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::start</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::start</span></span>:<br/>IF Module - <a href="1-im.html#SP4_1">&#167;4.1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Inferences::new_family</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"FOUND_IN_INF"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax">, </span><span class="identifier-syntax">LOG_DETAILS_INF_MTID</span><span class="plain-syntax">, </span><a href="3-bck.html#SP3" class="function-link"><span class="function-syntax">PL::Backdrops::log</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax">, </span><span class="identifier-syntax">COMPARE_INF_MTID</span><span class="plain-syntax">, </span><a href="3-bck.html#SP3" class="function-link"><span class="function-syntax">PL::Backdrops::cmp</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">FOUND_EVERYWHERE_INF</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Inferences::new_family</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="string-syntax">"FOUND_EVERYWHERE_INF"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">PluginManager::plug</span><span class="plain-syntax">(</span><span class="identifier-syntax">NEW_BASE_KIND_NOTIFY_PLUG</span><span class="plain-syntax">, </span><a href="3-bck.html#SP5" class="function-link"><span class="function-syntax">PL::Backdrops::backdrops_new_base_kind_notify</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">PluginManager::plug</span><span class="plain-syntax">(</span><span class="identifier-syntax">NEW_PROPERTY_NOTIFY_PLUG</span><span class="plain-syntax">, </span><a href="3-bck.html#SP8" class="function-link"><span class="function-syntax">PL::Backdrops::backdrops_new_property_notify</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">PluginManager::plug</span><span class="plain-syntax">(</span><span class="identifier-syntax">COMPLETE_MODEL_PLUG</span><span class="plain-syntax">, </span><a href="3-bck.html#SP15" class="function-link"><span class="function-syntax">PL::Backdrops::backdrops_complete_model</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">PluginManager::plug</span><span class="plain-syntax">(</span><span class="identifier-syntax">INTERVENE_IN_ASSERTION_PLUG</span><span class="plain-syntax">, </span><a href="3-bck.html#SP13" class="function-link"><span class="function-syntax">PL::Backdrops::backdrops_intervene_in_assertion</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">found_in_inference_data</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">inference_subject</span><span class="plain-syntax"> *</span><span class="identifier-syntax">location</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">CLASS_DEFINITION</span>
<span class="plain-syntax">} </span><span class="reserved-syntax">found_in_inference_data</span><span class="plain-syntax">;</span>
<span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="function-syntax">PL::Backdrops::new_found_in_inference</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::new_found_in_inference</span></span>:<br/><a href="3-bck.html#SP9">&#167;9</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">inference_subject</span><span class="plain-syntax"> *</span><span class="identifier-syntax">loc</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">certitude</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">PROTECTED_MODEL_PROCEDURE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">found_in_inference_data</span><span class="plain-syntax"> *</span><span class="identifier-syntax">data</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">found_in_inference_data</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">data</span><span class="plain-syntax">-&gt;</span><span class="identifier-syntax">location</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InferenceSubjects::divert</span><span class="plain-syntax">(</span><span class="identifier-syntax">loc</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">Inferences::create_inference</span><span class="plain-syntax">(</span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">STORE_POINTER_found_in_inference_data</span><span class="plain-syntax">(</span><span class="identifier-syntax">data</span><span class="plain-syntax">), </span><span class="identifier-syntax">certitude</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::log</span><span class="plain-syntax">(</span><span class="identifier-syntax">inference_family</span><span class="plain-syntax"> *</span><span class="identifier-syntax">f</span><span class="plain-syntax">, </span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">inf</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">found_in_inference_data</span><span class="plain-syntax"> *</span><span class="identifier-syntax">data</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RETRIEVE_POINTER_found_in_inference_data</span><span class="plain-syntax">(</span><span class="identifier-syntax">inf</span><span class="plain-syntax">-&gt;</span><span class="identifier-syntax">data</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">location</span><span class="plain-syntax">) </span><span class="identifier-syntax">LOG</span><span class="plain-syntax">(</span><span class="string-syntax">" in:$j"</span><span class="plain-syntax">, </span><span class="identifier-syntax">data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">location</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::cmp</span><span class="plain-syntax">(</span><span class="identifier-syntax">inference_family</span><span class="plain-syntax"> *</span><span class="identifier-syntax">f</span><span class="plain-syntax">, </span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">i1</span><span class="plain-syntax">, </span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">i2</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">found_in_inference_data</span><span class="plain-syntax"> *</span><span class="identifier-syntax">data1</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RETRIEVE_POINTER_found_in_inference_data</span><span class="plain-syntax">(</span><span class="identifier-syntax">i1</span><span class="plain-syntax">-&gt;</span><span class="identifier-syntax">data</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">found_in_inference_data</span><span class="plain-syntax"> *</span><span class="identifier-syntax">data2</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RETRIEVE_POINTER_found_in_inference_data</span><span class="plain-syntax">(</span><span class="identifier-syntax">i2</span><span class="plain-syntax">-&gt;</span><span class="identifier-syntax">data</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">c</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Inferences::measure_infs</span><span class="plain-syntax">(</span><span class="identifier-syntax">data1</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">location</span><span class="plain-syntax">) -</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Inferences::measure_infs</span><span class="plain-syntax">(</span><span class="identifier-syntax">data2</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">location</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">c</span><span class="plain-syntax"> &gt; </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">CI_DIFFER_IN_TOPIC</span><span class="plain-syntax">; </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">c</span><span class="plain-syntax"> &lt; </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> -</span><span class="identifier-syntax">CI_DIFFER_IN_TOPIC</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">c</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Inferences::measure_inf</span><span class="plain-syntax">(</span><span class="identifier-syntax">i1</span><span class="plain-syntax">) - </span><span class="identifier-syntax">Inferences::measure_inf</span><span class="plain-syntax">(</span><span class="identifier-syntax">i2</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">c</span><span class="plain-syntax"> &gt; </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">CI_DIFFER_IN_COPY_ONLY</span><span class="plain-syntax">; </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">c</span><span class="plain-syntax"> &lt; </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> -</span><span class="identifier-syntax">CI_DIFFER_IN_COPY_ONLY</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">CI_IDENTICAL</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="function-syntax">PL::Backdrops::get_inferred_location</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::get_inferred_location</span></span>:<br/><a href="3-bck.html#SP10">&#167;10</a>, <a href="3-bck.html#SP15_2">&#167;15.2</a>, <a href="3-bck.html#SP15_3">&#167;15.3</a>, <a href="3-bck.html#SP16_1">&#167;16.1</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">i</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">i</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">i</span><span class="plain-syntax">-&gt;</span><span class="identifier-syntax">family</span><span class="plain-syntax"> != </span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"not a FOUND_IN_INF inf"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">found_in_inference_data</span><span class="plain-syntax"> *</span><span class="identifier-syntax">data</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RETRIEVE_POINTER_found_in_inference_data</span><span class="plain-syntax">(</span><span class="identifier-syntax">i</span><span class="plain-syntax">-&gt;</span><span class="identifier-syntax">data</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">InstanceSubjects::to_instance</span><span class="plain-syntax">(</span><span class="identifier-syntax">data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">location</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<ul class="endnotetexts"><li>The structure found_in_inference_data is private to this section.</li></ul>
<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. Kinds. </b>This a kind name to do with backdrops which Inform provides special support
for; it recognises the English name when defined by the Standard Rules. (So
there is no need to translate this to other languages.)
</p>
<pre class="Preform-displayed-code all-displayed-code code-font">
<span class="Preform-function-syntax">&lt;notable-backdrops-kinds&gt;</span><span class="Preform-plain-syntax"> </span><span class="Preform-reserved-syntax">::=</span>
<span class="Preform-plain-syntax"> </span><span class="Preform-constant-syntax">backdrop</span>
</pre>
<ul class="endnotetexts"><li>This is <a href="../words-module/4-ap.html" class="internal">Preform grammar</a>, not regular C code.</li></ul>
<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>&#167;5. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::backdrops_new_base_kind_notify</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::backdrops_new_base_kind_notify</span></span>:<br/><a href="3-bck.html#SP3">&#167;3</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">new_base</span><span class="plain-syntax">, </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">name</span><span class="plain-syntax">, </span><span class="identifier-syntax">wording</span><span class="plain-syntax"> </span><span class="identifier-syntax">W</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="function-syntax">&lt;notable-backdrops-kinds&gt;</span><span class="plain-syntax">(</span><span class="identifier-syntax">W</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">K_backdrop</span><span class="plain-syntax"> = </span><span class="identifier-syntax">new_base</span><span class="plain-syntax">; </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>&#167;6. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::object_is_a_backdrop</span><button class="popup" onclick="togglePopup('usagePopup5')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup5">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::object_is_a_backdrop</span></span>:<br/><a href="3-bck.html#SP10">&#167;10</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">I</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">PluginManager::active</span><span class="plain-syntax">(</span><span class="identifier-syntax">regions_plugin</span><span class="plain-syntax">)) &amp;&amp; (</span><span class="identifier-syntax">K_backdrop</span><span class="plain-syntax">) &amp;&amp; (</span><span class="identifier-syntax">I</span><span class="plain-syntax">) &amp;&amp;</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">Instances::of_kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_backdrop</span><span class="plain-syntax">))) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP7" class="paragraph-anchor"></a><b>&#167;7. Properties. </b>This is a property name to do with backdrops which Inform provides special
support for; it recognises the English name when it is defined by the
Standard Rules. (So there is no need to translate this to other languages.)
</p>
<pre class="Preform-displayed-code all-displayed-code code-font">
<span class="Preform-function-syntax">&lt;notable-backdrops-properties&gt;</span><span class="Preform-plain-syntax"> </span><span class="Preform-reserved-syntax">::=</span>
<span class="Preform-plain-syntax"> </span><span class="Preform-constant-syntax">scenery</span>
</pre>
<ul class="endnotetexts"><li>This is <a href="../words-module/4-ap.html" class="internal">Preform grammar</a>, not regular C code.</li></ul>
<p class="commentary firstcommentary"><a id="SP8" class="paragraph-anchor"></a><b>&#167;8. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::backdrops_new_property_notify</span><button class="popup" onclick="togglePopup('usagePopup6')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup6">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::backdrops_new_property_notify</span></span>:<br/><a href="3-bck.html#SP3">&#167;3</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="function-syntax">&lt;notable-backdrops-properties&gt;(prn-&gt;</span><span class="element-syntax">name</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">P_scenery</span><span class="plain-syntax"> = </span><span class="identifier-syntax">prn</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::object_is_scenery</span><button class="popup" onclick="togglePopup('usagePopup7')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup7">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::object_is_scenery</span></span>:<br/>Spatial Model - <a href="3-sm.html#SP19">&#167;19</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">I</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">PropertyInferences::either_or_state</span><span class="plain-syntax">(</span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">), </span><span class="identifier-syntax">P_scenery</span><span class="plain-syntax">) &gt; </span><span class="constant-syntax">0</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP9" class="paragraph-anchor"></a><b>&#167;9. </b>Here we look at "in" and "part of" relationships to see if they concern
backdrops; if they do, then they need to become <span class="extract"><span class="extract-syntax">FOUND_IN_INF</span></span> inferences.
Without this intervention, they'd be subject to the usual spatial rules
and text like
</p>
<blockquote>
<p>The sky is in the Grand Balcony. The sky is in the Vizier's Lawn.</p>
</blockquote>
<p class="commentary">would lead to contradiction problem messages.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::assert_relations</span><button class="popup" onclick="togglePopup('usagePopup8')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup8">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::assert_relations</span></span>:<br/>Spatial Relations - <a href="3-sr.html#SP4_1">&#167;4.1</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">binary_predicate</span><span class="plain-syntax"> *</span><span class="identifier-syntax">relation</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">I0</span><span class="plain-syntax">, </span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">I1</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">Instances::of_kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">I1</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_backdrop</span><span class="plain-syntax">)) &amp;&amp;</span>
<span class="plain-syntax"> ((</span><span class="identifier-syntax">relation</span><span class="plain-syntax"> == </span><span class="identifier-syntax">R_incorporation</span><span class="plain-syntax">) ||</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">relation</span><span class="plain-syntax"> == </span><span class="identifier-syntax">R_containment</span><span class="plain-syntax">) ||</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">relation</span><span class="plain-syntax"> == </span><span class="identifier-syntax">R_regional_containment</span><span class="plain-syntax">))) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inference_subject</span><span class="plain-syntax"> *</span><span class="identifier-syntax">bd</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">I1</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inference_subject</span><span class="plain-syntax"> *</span><span class="identifier-syntax">loc</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">I0</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-sm.html#SP4" class="function-link"><span class="function-syntax">PL::Spatial::infer_part_of</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">bd</span><span class="plain-syntax">, </span><span class="identifier-syntax">IMPOSSIBLE_CE</span><span class="plain-syntax">, </span><span class="identifier-syntax">loc</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-sm.html#SP4" class="function-link"><span class="function-syntax">PL::Spatial::infer_is_room</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">bd</span><span class="plain-syntax">, </span><span class="identifier-syntax">IMPOSSIBLE_CE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">i</span><span class="plain-syntax"> = </span><a href="3-bck.html#SP3" class="function-link"><span class="function-syntax">PL::Backdrops::new_found_in_inference</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">loc</span><span class="plain-syntax">, </span><span class="identifier-syntax">CERTAIN_CE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Inferences::join_inference</span><span class="plain-syntax">(</span><span class="identifier-syntax">i</span><span class="plain-syntax">, </span><span class="identifier-syntax">bd</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP10" class="paragraph-anchor"></a><b>&#167;10. </b>For indexing purposes, the following loops are useful:
</p>
<pre class="definitions code-font"><span class="definition-keyword">define</span> <span class="identifier-syntax">LOOP_OVER_BACKDROPS_IN</span><span class="plain-syntax">(</span><span class="identifier-syntax">B</span><span class="plain-syntax">, </span><span class="identifier-syntax">P</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_INSTANCES</span><span class="plain-syntax">(</span><span class="identifier-syntax">B</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_object</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-bck.html#SP6" class="function-link"><span class="function-syntax">PL::Backdrops::object_is_a_backdrop</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">B</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">POSITIVE_KNOWLEDGE_LOOP</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">, </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">B</span><span class="plain-syntax">), </span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-bck.html#SP3" class="function-link"><span class="function-syntax">PL::Backdrops::get_inferred_location</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">) == </span><span class="identifier-syntax">P</span><span class="plain-syntax">)</span>
<span class="definition-keyword">define</span> <span class="identifier-syntax">LOOP_OVER_BACKDROPS_EVERYWHERE</span><span class="plain-syntax">(</span><span class="identifier-syntax">B</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_INSTANCES</span><span class="plain-syntax">(</span><span class="identifier-syntax">B</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_object</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-bck.html#SP6" class="function-link"><span class="function-syntax">PL::Backdrops::object_is_a_backdrop</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">B</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">POSITIVE_KNOWLEDGE_LOOP</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">, </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">B</span><span class="plain-syntax">), </span><span class="identifier-syntax">FOUND_EVERYWHERE_INF</span><span class="plain-syntax">)</span>
</pre>
<p class="commentary firstcommentary"><a id="SP11" class="paragraph-anchor"></a><b>&#167;11. </b>Since backdrops are contained using different mechanisms, the following
(which does nothing if Backdrops isn't plugged in) adds backdrop contents to
a room called <span class="extract"><span class="extract-syntax">loc</span></span>, or lists backdrops which are "everywhere" if <span class="extract"><span class="extract-syntax">loc</span></span>
is <span class="extract"><span class="extract-syntax">NULL</span></span>.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::index_object_further</span><button class="popup" onclick="togglePopup('usagePopup9')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup9">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::index_object_further</span></span>:<br/>Spatial Model - <a href="3-sm.html#SP44">&#167;44</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">OUTPUT_STREAM</span><span class="plain-syntax">, </span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">loc</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">depth</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">details</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">how</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">discoveries</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">bd</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">inf</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">loc</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_BACKDROPS_IN</span><span class="plain-syntax">(</span><span class="identifier-syntax">bd</span><span class="plain-syntax">, </span><span class="identifier-syntax">loc</span><span class="plain-syntax">, </span><span class="identifier-syntax">inf</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (++</span><span class="identifier-syntax">discoveries</span><span class="plain-syntax"> == </span><span class="constant-syntax">1</span><span class="plain-syntax">) </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP11_1" class="named-paragraph-link"><span class="named-paragraph">Insert fore-matter</span><span class="named-paragraph-number">11.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Data::Objects::index</span><span class="plain-syntax">(</span><span class="identifier-syntax">OUT</span><span class="plain-syntax">, </span><span class="identifier-syntax">bd</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">depth</span><span class="plain-syntax">+1, </span><span class="identifier-syntax">details</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_BACKDROPS_EVERYWHERE</span><span class="plain-syntax">(</span><span class="identifier-syntax">bd</span><span class="plain-syntax">, </span><span class="identifier-syntax">inf</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (++</span><span class="identifier-syntax">discoveries</span><span class="plain-syntax"> == </span><span class="constant-syntax">1</span><span class="plain-syntax">) </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP11_1" class="named-paragraph-link"><span class="named-paragraph">Insert fore-matter</span><span class="named-paragraph-number">11.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Data::Objects::index</span><span class="plain-syntax">(</span><span class="identifier-syntax">OUT</span><span class="plain-syntax">, </span><span class="identifier-syntax">bd</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">depth</span><span class="plain-syntax">+1, </span><span class="identifier-syntax">details</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">discoveries</span><span class="plain-syntax"> &gt; </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP11_2" class="named-paragraph-link"><span class="named-paragraph">Insert after-matter</span><span class="named-paragraph-number">11.2</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP11_1" class="paragraph-anchor"></a><b>&#167;11.1. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Insert fore-matter</span><span class="named-paragraph-number">11.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">switch</span><span class="plain-syntax"> (</span><span class="identifier-syntax">how</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">case</span><span class="plain-syntax"> </span><span class="constant-syntax">1</span><span class="plain-syntax">: </span><span class="identifier-syntax">HTML_OPEN</span><span class="plain-syntax">(</span><span class="string-syntax">"p"</span><span class="plain-syntax">); </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"&lt;b&gt;Present everywhere:&lt;/b&gt;"</span><span class="plain-syntax">); </span><span class="identifier-syntax">HTML_TAG</span><span class="plain-syntax">(</span><span class="string-syntax">"br"</span><span class="plain-syntax">); </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">case</span><span class="plain-syntax"> </span><span class="constant-syntax">2</span><span class="plain-syntax">: </span><span class="identifier-syntax">HTML_TAG</span><span class="plain-syntax">(</span><span class="string-syntax">"br"</span><span class="plain-syntax">); </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-bck.html#SP11">&#167;11</a> (twice).</li></ul>
<p class="commentary firstcommentary"><a id="SP11_2" class="paragraph-anchor"></a><b>&#167;11.2. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Insert after-matter</span><span class="named-paragraph-number">11.2</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">switch</span><span class="plain-syntax"> (</span><span class="identifier-syntax">how</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">case</span><span class="plain-syntax"> </span><span class="constant-syntax">1</span><span class="plain-syntax">: </span><span class="identifier-syntax">HTML_CLOSE</span><span class="plain-syntax">(</span><span class="string-syntax">"p"</span><span class="plain-syntax">); </span><span class="identifier-syntax">HTML_TAG</span><span class="plain-syntax">(</span><span class="string-syntax">"hr"</span><span class="plain-syntax">); </span><span class="identifier-syntax">HTML_OPEN</span><span class="plain-syntax">(</span><span class="string-syntax">"p"</span><span class="plain-syntax">); </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">case</span><span class="plain-syntax"> </span><span class="constant-syntax">2</span><span class="plain-syntax">: </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-bck.html#SP11">&#167;11</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP12" class="paragraph-anchor"></a><b>&#167;12. Everywhere. </b>Here we defines a form of noun phrase special to Backdrops (because a backdrop
can be said to be "everywhere", which nothing else can).
</p>
<pre class="Preform-displayed-code all-displayed-code code-font">
<span class="Preform-function-syntax">&lt;notable-backdrops-noun-phrases&gt;</span><span class="Preform-plain-syntax"> </span><span class="Preform-reserved-syntax">::=</span>
<span class="Preform-plain-syntax"> </span><span class="Preform-constant-syntax">everywhere</span>
</pre>
<ul class="endnotetexts"><li>This is <a href="../words-module/4-ap.html" class="internal">Preform grammar</a>, not regular C code.</li></ul>
<p class="commentary firstcommentary"><a id="SP13" class="paragraph-anchor"></a><b>&#167;13. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::backdrops_intervene_in_assertion</span><button class="popup" onclick="togglePopup('usagePopup10')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup10">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::backdrops_intervene_in_assertion</span></span>:<br/><a href="3-bck.html#SP3">&#167;3</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">parse_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">px</span><span class="plain-syntax">, </span><span class="identifier-syntax">parse_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">py</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">Node::get_type</span><span class="plain-syntax">(</span><span class="identifier-syntax">py</span><span class="plain-syntax">) == </span><span class="identifier-syntax">EVERY_NT</span><span class="plain-syntax">) &amp;&amp;</span>
<span class="plain-syntax"> (</span><span class="function-syntax">&lt;notable-backdrops-noun-phrases&gt;</span><span class="plain-syntax">(</span><span class="identifier-syntax">Node::get_text</span><span class="plain-syntax">(</span><span class="identifier-syntax">py</span><span class="plain-syntax">)))) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inference_subject</span><span class="plain-syntax"> *</span><span class="identifier-syntax">left_subject</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Node::get_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">px</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">left_subject</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Problems::Using::assertion_problem</span><span class="plain-syntax">(</span><span class="identifier-syntax">Task::syntax_tree</span><span class="plain-syntax">(), </span><span class="identifier-syntax">_p_</span><span class="plain-syntax">(</span><span class="identifier-syntax">PM_ValueEverywhere</span><span class="plain-syntax">),</span>
<span class="plain-syntax"> </span><span class="string-syntax">"'everywhere' can only be used to place individual backdrops"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"so although 'The mist is a backdrop. The mist is everywhere.' "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"would be fine, 'Corruption is everywhere.' would not."</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">KindSubjects::to_kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">left_subject</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">StandardProblems::subject_problem_at_sentence</span><span class="plain-syntax">(</span><span class="identifier-syntax">_p_</span><span class="plain-syntax">(</span><span class="identifier-syntax">PM_KindOfBackdropEverywhere</span><span class="plain-syntax">),</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">left_subject</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"seems to be said to be 'everywhere' in some way"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"which doesn't make sense. An individual backdrop can be 'everywhere', "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"but here we're talking about a whole kind, and it's not allowed "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"to talk about general locations of a whole kind of things at once."</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="identifier-syntax">Assert::true_about</span><span class="plain-syntax">(</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Propositions::Abstract::to_put_everywhere</span><span class="plain-syntax">(), </span><span class="identifier-syntax">left_subject</span><span class="plain-syntax">, </span><span class="identifier-syntax">prevailing_mood</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP14" class="paragraph-anchor"></a><b>&#167;14. </b>And this is where it makes the necessary inference after such a request has
been asserted true:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::infer_presence_everywhere</span><button class="popup" onclick="togglePopup('usagePopup11')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup11">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::infer_presence_everywhere</span></span>:<br/>Everywhere, Nowhere and Here - <a href="3-enah.html#SP5">&#167;5</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">I</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">I</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">Instances::of_kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_backdrop</span><span class="plain-syntax">) == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">StandardProblems::sentence_problem</span><span class="plain-syntax">(</span><span class="identifier-syntax">Task::syntax_tree</span><span class="plain-syntax">(), </span><span class="identifier-syntax">_p_</span><span class="plain-syntax">(</span><span class="identifier-syntax">PM_EverywhereNonBackdrop</span><span class="plain-syntax">),</span>
<span class="plain-syntax"> </span><span class="string-syntax">"only a backdrop can be everywhere"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"and no other kind of object will do. For instance, 'The sky is "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"a backdrop which is everywhere.' is allowed, but 'The travelator "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"is a vehicle which is everywhere.' is not."</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Inferences::join_inference</span><span class="plain-syntax">(</span><span class="identifier-syntax">Inferences::create_inference</span><span class="plain-syntax">(</span><span class="identifier-syntax">FOUND_EVERYWHERE_INF</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL_GENERAL_POINTER</span><span class="plain-syntax">, </span><span class="identifier-syntax">prevailing_mood</span><span class="plain-syntax">), </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">));</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP15" class="paragraph-anchor"></a><b>&#167;15. Model completion. </b>We intervene only at Stage II, the spatial modelling stage.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::backdrops_complete_model</span><button class="popup" onclick="togglePopup('usagePopup12')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup12">Usage of <span class="code-font"><span class="function-syntax">PL::Backdrops::backdrops_complete_model</span></span>:<br/><a href="3-bck.html#SP3">&#167;3</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">stage</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">stage</span><span class="plain-syntax"> == </span><span class="identifier-syntax">WORLD_STAGE_II</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">P_absent</span><span class="plain-syntax"> = </span><span class="identifier-syntax">EitherOrProperties::new_nameless</span><span class="plain-syntax">(</span><span class="identifier-syntax">L</span><span class="string-syntax">"absent"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTProperties::implement_as_attribute</span><span class="plain-syntax">(</span><span class="identifier-syntax">P_absent</span><span class="plain-syntax">, </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">I</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_INSTANCES</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_object</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP15_1" class="named-paragraph-link"><span class="named-paragraph">If the object is found everywhere, make a found-in property accordingly</span><span class="named-paragraph-number">15.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">room_count</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">, </span><span class="identifier-syntax">region_count</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP15_2" class="named-paragraph-link"><span class="named-paragraph">Find how many rooms or regions the object is found inside</span><span class="named-paragraph-number">15.2</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) &amp;&amp; (</span><span class="identifier-syntax">room_count</span><span class="plain-syntax"> &gt; </span><span class="constant-syntax">0</span><span class="plain-syntax">) &amp;&amp; (</span><span class="identifier-syntax">room_count</span><span class="plain-syntax"> &lt; </span><span class="constant-syntax">16</span><span class="plain-syntax">) &amp;&amp; (</span><span class="identifier-syntax">region_count</span><span class="plain-syntax"> == </span><span class="constant-syntax">0</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP15_3" class="named-paragraph-link"><span class="named-paragraph">The object is found only in a few rooms, and no regions, so make it a list</span><span class="named-paragraph-number">15.3</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) &amp;&amp; (</span><span class="identifier-syntax">room_count</span><span class="plain-syntax"> + </span><span class="identifier-syntax">region_count</span><span class="plain-syntax"> &gt; </span><span class="constant-syntax">0</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP15_4" class="named-paragraph-link"><span class="named-paragraph">The object is found in many rooms or in whole regions, so make it a routine</span><span class="named-paragraph-number">15.4</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) &amp;&amp; (</span><span class="identifier-syntax">Instances::of_kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_backdrop</span><span class="plain-syntax">)))</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP15_5" class="named-paragraph-link"><span class="named-paragraph">The object is found nowhere, so give it a stub found-in property and mark it absent</span><span class="named-paragraph-number">15.5</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax">) </span><a href="3-tm.html#SP26" class="function-link"><span class="function-syntax">PL::Map::set_found_in</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">, </span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP15_1" class="paragraph-anchor"></a><b>&#167;15.1. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">If the object is found everywhere, make a found-in property accordingly</span><span class="named-paragraph-number">15.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">inf</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">POSITIVE_KNOWLEDGE_LOOP</span><span class="plain-syntax">(</span><span class="identifier-syntax">inf</span><span class="plain-syntax">, </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">), </span><span class="identifier-syntax">FOUND_EVERYWHERE_INF</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::find</span><span class="plain-syntax">(</span><span class="identifier-syntax">FOUND_EVERYWHERE_HL</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-bck.html#SP15">&#167;15</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP15_2" class="paragraph-anchor"></a><b>&#167;15.2. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Find how many rooms or regions the object is found inside</span><span class="named-paragraph-number">15.2</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">inf</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">POSITIVE_KNOWLEDGE_LOOP</span><span class="plain-syntax">(</span><span class="identifier-syntax">inf</span><span class="plain-syntax">, </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">), </span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">loc</span><span class="plain-syntax"> = </span><a href="3-bck.html#SP3" class="function-link"><span class="function-syntax">PL::Backdrops::get_inferred_location</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">inf</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">K_region</span><span class="plain-syntax">) &amp;&amp; (</span><span class="identifier-syntax">Instances::of_kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">loc</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_region</span><span class="plain-syntax">))) </span><span class="identifier-syntax">region_count</span><span class="plain-syntax">++;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="identifier-syntax">room_count</span><span class="plain-syntax">++;</span>
<span class="plain-syntax"> }</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-bck.html#SP15">&#167;15</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP15_3" class="paragraph-anchor"></a><b>&#167;15.3. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">The object is found only in a few rooms, and no regions, so make it a list</span><span class="named-paragraph-number">15.3</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">package_request</span><span class="plain-syntax"> *</span><span class="identifier-syntax">PR</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::package_within</span><span class="plain-syntax">(</span><span class="identifier-syntax">INLINE_PROPERTIES_HAP</span><span class="plain-syntax">, </span><span class="identifier-syntax">RTInstances::package</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::make_iname_in</span><span class="plain-syntax">(</span><span class="identifier-syntax">INLINE_PROPERTY_HL</span><span class="plain-syntax">, </span><span class="identifier-syntax">PR</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">packaging_state</span><span class="plain-syntax"> </span><span class="identifier-syntax">save</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Emit::named_array_begin</span><span class="plain-syntax">(</span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_value</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">inf</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">POSITIVE_KNOWLEDGE_LOOP</span><span class="plain-syntax">(</span><span class="identifier-syntax">inf</span><span class="plain-syntax">, </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">), </span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Emit::array_iname_entry</span><span class="plain-syntax">(</span><span class="identifier-syntax">RTInstances::iname</span><span class="plain-syntax">(</span><a href="3-bck.html#SP3" class="function-link"><span class="function-syntax">PL::Backdrops::get_inferred_location</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">inf</span><span class="plain-syntax">)));</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Emit::array_end</span><span class="plain-syntax">(</span><span class="identifier-syntax">save</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::annotate_i</span><span class="plain-syntax">(</span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax">, </span><span class="identifier-syntax">INLINE_ARRAY_IANN</span><span class="plain-syntax">, </span><span class="constant-syntax">1</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-bck.html#SP15">&#167;15</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP15_4" class="paragraph-anchor"></a><b>&#167;15.4. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">The object is found in many rooms or in whole regions, so make it a routine</span><span class="named-paragraph-number">15.4</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">backdrop_found_in_notice</span><span class="plain-syntax"> *</span><span class="identifier-syntax">notice</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">backdrop_found_in_notice</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">backdrop</span><span class="plain-syntax"> = </span><span class="identifier-syntax">I</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">package_request</span><span class="plain-syntax"> *</span><span class="identifier-syntax">R</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RTInstances::package</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">found_in_routine_iname</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::make_iname_in</span><span class="plain-syntax">(</span><span class="identifier-syntax">BACKDROP_FOUND_IN_FN_HL</span><span class="plain-syntax">, </span><span class="identifier-syntax">R</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">many_places</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax"> = </span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">found_in_routine_iname</span><span class="plain-syntax">;</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-bck.html#SP15">&#167;15</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP15_5" class="paragraph-anchor"></a><b>&#167;15.5. </b><span class="extract"><span class="extract-syntax">absent</span></span> is an I6-only attribute which marks a backdrop has having been removed
from the world model. It's not sufficient for an object's <span class="extract"><span class="extract-syntax">found_in</span></span> always to
say no to the question "are you in the current location?"; the I6 template
code, derived from the old I6 library, requires <span class="extract"><span class="extract-syntax">absent</span></span> to be set. So:
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">The object is found nowhere, so give it a stub found-in property and mark it absent</span><span class="named-paragraph-number">15.5</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">backdrop_found_in_notice</span><span class="plain-syntax"> *</span><span class="identifier-syntax">notice</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">backdrop_found_in_notice</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">backdrop</span><span class="plain-syntax"> = </span><span class="identifier-syntax">I</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">package_request</span><span class="plain-syntax"> *</span><span class="identifier-syntax">R</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RTInstances::package</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">found_in_routine_iname</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::make_iname_in</span><span class="plain-syntax">(</span><span class="identifier-syntax">BACKDROP_FOUND_IN_FN_HL</span><span class="plain-syntax">, </span><span class="identifier-syntax">R</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">many_places</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">FOUNDIN</span><span class="plain-syntax"> = </span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">found_in_routine_iname</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">EitherOrProperties::assert</span><span class="plain-syntax">(</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">P_absent</span><span class="plain-syntax">, </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">), </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">, </span><span class="identifier-syntax">CERTAIN_CE</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-bck.html#SP15">&#167;15</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP16" class="paragraph-anchor"></a><b>&#167;16. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">PL::Backdrops::write_found_in_routines</span><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">backdrop_found_in_notice</span><span class="plain-syntax"> *</span><span class="identifier-syntax">notice</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER</span><span class="plain-syntax">(</span><span class="identifier-syntax">notice</span><span class="plain-syntax">, </span><span class="reserved-syntax">backdrop_found_in_notice</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">I</span><span class="plain-syntax"> = </span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">backdrop</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">many_places</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP16_1" class="named-paragraph-link"><span class="named-paragraph">The object is found in many rooms or in whole regions</span><span class="named-paragraph-number">16.1</span></a></span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-bck.html#SP16_2" class="named-paragraph-link"><span class="named-paragraph">The object is found nowhere</span><span class="named-paragraph-number">16.2</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP16_1" class="paragraph-anchor"></a><b>&#167;16.1. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">The object is found in many rooms or in whole regions</span><span class="named-paragraph-number">16.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">packaging_state</span><span class="plain-syntax"> </span><span class="identifier-syntax">save</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Routines::begin</span><span class="plain-syntax">(</span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">found_in_routine_iname</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inference</span><span class="plain-syntax"> *</span><span class="identifier-syntax">inf</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">POSITIVE_KNOWLEDGE_LOOP</span><span class="plain-syntax">(</span><span class="identifier-syntax">inf</span><span class="plain-syntax">, </span><span class="identifier-syntax">Instances::as_subject</span><span class="plain-syntax">(</span><span class="identifier-syntax">I</span><span class="plain-syntax">), </span><span class="identifier-syntax">FOUND_IN_INF</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">instance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">loc</span><span class="plain-syntax"> = </span><a href="3-bck.html#SP3" class="function-link"><span class="function-syntax">PL::Backdrops::get_inferred_location</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">inf</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::inv_primitive</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">(), </span><span class="identifier-syntax">IF_BIP</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::down</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">K_region</span><span class="plain-syntax">) &amp;&amp; (</span><span class="identifier-syntax">Instances::of_kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">loc</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_region</span><span class="plain-syntax">))) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::inv_call_iname</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">(), </span><span class="identifier-syntax">Hierarchy::find</span><span class="plain-syntax">(</span><span class="identifier-syntax">TESTREGIONALCONTAINMENT_HL</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::down</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::val_iname</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">(), </span><span class="identifier-syntax">K_object</span><span class="plain-syntax">, </span><span class="identifier-syntax">Hierarchy::find</span><span class="plain-syntax">(</span><span class="identifier-syntax">LOCATION_HL</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::val_iname</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">(), </span><span class="identifier-syntax">K_object</span><span class="plain-syntax">, </span><span class="identifier-syntax">RTInstances::iname</span><span class="plain-syntax">(</span><span class="identifier-syntax">loc</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::up</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::inv_primitive</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">(), </span><span class="identifier-syntax">EQ_BIP</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::down</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::val_iname</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">(), </span><span class="identifier-syntax">K_object</span><span class="plain-syntax">, </span><span class="identifier-syntax">Hierarchy::find</span><span class="plain-syntax">(</span><span class="identifier-syntax">LOCATION_HL</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::val_iname</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">(), </span><span class="identifier-syntax">K_object</span><span class="plain-syntax">, </span><span class="identifier-syntax">RTInstances::iname</span><span class="plain-syntax">(</span><span class="identifier-syntax">loc</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::up</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::code</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::down</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::rtrue</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::up</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::up</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::rfalse</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Routines::end</span><span class="plain-syntax">(</span><span class="identifier-syntax">save</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-bck.html#SP16">&#167;16</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP16_2" class="paragraph-anchor"></a><b>&#167;16.2. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">The object is found nowhere</span><span class="named-paragraph-number">16.2</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">packaging_state</span><span class="plain-syntax"> </span><span class="identifier-syntax">save</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Routines::begin</span><span class="plain-syntax">(</span><span class="identifier-syntax">notice</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">found_in_routine_iname</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Produce::rfalse</span><span class="plain-syntax">(</span><span class="identifier-syntax">Emit::tree</span><span class="plain-syntax">());</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Routines::end</span><span class="plain-syntax">(</span><span class="identifier-syntax">save</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-bck.html#SP16">&#167;16</a>.</li></ul>
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