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< ul class = "crumbs" > < li > < a href = "../index.html" > Home< / a > < / li > < li > < a href = "../inform7n.html" > Inform7< / a > < / li > < li > < a href = "index.html" > knowledge< / a > < / li > < li > < a href = "index.html#4" > Chapter 4: Subjects< / a > < / li > < li > < b > Variable Subjects< / b > < / li > < / ul > < / div >
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< p class = "purpose" > The global variables family of inference subjects.< / p >
< p class = "commentary firstcommentary" > < a id = "SP1" class = "paragraph-anchor" > < / a > < b > § 1. < / b > Variables are subjects for one purpose only: so that their purported initial
values can be declared and checked as being property values, of the special
property < span class = "extract" > < span class = "extract-syntax" > P_variable_initial_value< / span > < / span > .
< / p >
< pre class = "displayed-code all-displayed-code code-font" >
< span class = "reserved-syntax" > inference_subject_family< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nlv_family< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "reserved-syntax" > inference_subject_family< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > VariableSubjects::family< / 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" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv_family< / 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" > nlv_family< / span > < span class = "plain-syntax" > = < / span > < a href = "4-is.html#SP1" class = "function-link" > < span class = "function-syntax" > InferenceSubjects::new_family< / 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" > nlv_family< / span > < span class = "plain-syntax" > , < / span > < span class = "constant-syntax" > GET_DEFAULT_CERTAINTY_INFS_MTID< / span > < span class = "plain-syntax" > , < / span > < a href = "4-vs.html#SP1" class = "function-link" > < span class = "function-syntax" > VariableSubjects::certainty< / 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" > nlv_family< / span > < span class = "plain-syntax" > , < / span > < span class = "constant-syntax" > CHECK_MODEL_INFS_MTID< / span > < span class = "plain-syntax" > , < / span > < a href = "4-vs.html#SP4" class = "function-link" > < span class = "function-syntax" > VariableSubjects::check_model< / 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" > nlv_family< / span > < span class = "plain-syntax" > , < / span > < span class = "constant-syntax" > GET_NAME_TEXT_INFS_MTID< / span > < span class = "plain-syntax" > , < / span > < a href = "4-vs.html#SP1" class = "function-link" > < span class = "function-syntax" > VariableSubjects::get_name< / span > < / a > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > METHOD_ADD< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv_family< / span > < span class = "plain-syntax" > , < / span > < span class = "constant-syntax" > EMIT_ALL_INFS_MTID< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > RTVariables::compile< / span > < span class = "plain-syntax" > );< / span >
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< 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" > nlv_family< / 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" > VariableSubjects::certainty< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > inference_subject_family< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > f< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > inference_subject< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > infs< / 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" > CERTAIN_CE< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< span class = "reserved-syntax" > nonlocal_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > VariableSubjects::to_variable< / 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" > VariableSubjects::to_variable< / span > < / span > :< br / > < a href = "4-vs.html#SP4" > § 4< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > inference_subject< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > infs< / 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" > infs< / span > < span class = "plain-syntax" > ) & & (< / span > < span class = "identifier-syntax" > infs< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > infs_family< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > nlv_family< / 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" > RETRIEVE_POINTER_nonlocal_variable< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > infs< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > represents< / 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" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "reserved-syntax" > inference_subject< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > VariableSubjects::new< / 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" > VariableSubjects::new< / span > < / span > :< br / > Nonlocal Variables - < a href = "2-nv.html#SP4" > § 4< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > nonlocal_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < a href = "4-is.html#SP7" class = "function-link" > < span class = "function-syntax" > InferenceSubjects::new< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > global_variables< / span > < span class = "plain-syntax" > ,< / span >
< span class = "plain-syntax" > < / span > < a href = "4-vs.html#SP1" class = "function-link" > < span class = "function-syntax" > VariableSubjects::family< / span > < / a > < span class = "plain-syntax" > (), < / span > < span class = "identifier-syntax" > STORE_POINTER_nonlocal_variable< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > ), < / span > < span class = "identifier-syntax" > NULL< / 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" > VariableSubjects::get_name< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > inference_subject_family< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > family< / span > < span class = "plain-syntax" > ,< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > inference_subject< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > from< / 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" > nonlocal_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > = < / span > < a href = "4-vs.html#SP1" class = "function-link" > < span class = "function-syntax" > VariableSubjects::to_variable< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > from< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > W< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > name< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< / pre >
< p class = "commentary firstcommentary" > < a id = "SP2" class = "paragraph-anchor" > < / a > < b > § 2. < / b > The initial value of a variable is stored as the value of the subject's
property < span class = "extract" > < span class = "extract-syntax" > P_variable_initial_value< / span > < / span > . Attempts to store two different
values in the same variable are thus rejected as contradictory inferences
about the same subject.
< / p >
< pre class = "displayed-code all-displayed-code code-font" >
< span class = "reserved-syntax" > inference< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > VariableSubjects::get_initial_value_inference< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > nonlocal_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nlv< / 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" > nlv< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > inference_subject< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > infs< / span > < span class = "plain-syntax" > = < / span > < a href = "2-nv.html#SP8" class = "function-link" > < span class = "function-syntax" > NonlocalVariables::to_subject< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > inference< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > inf< / span > < span class = "plain-syntax" > ;< / span >
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< 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" > infs< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > property_inf< / span > < span class = "plain-syntax" > )< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < a href = "5-pi.html#SP7" class = "function-link" > < span class = "function-syntax" > PropertyInferences::get_property< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > inf< / span > < span class = "plain-syntax" > ) == < / span > < span class = "identifier-syntax" > P_variable_initial_value< / span > < span class = "plain-syntax" > )< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > inf< / 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" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > VariableSubjects::get_initial_value< / 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" > VariableSubjects::get_initial_value< / span > < / span > :< br / > < a href = "4-vs.html#SP4" > § 4< / a > < br / > Nonlocal Variables - < a href = "2-nv.html#SP13" > § 13< / a > , < a href = "2-nv.html#SP14" > § 14< / a > < br / > Inference Subjects - < a href = "4-is.html#SP8" > § 8< / a > , < a href = "4-is.html#SP9" > § 9< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > nonlocal_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > inference< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > inf< / span > < span class = "plain-syntax" > = < / span > < a href = "4-vs.html#SP2" class = "function-link" > < span class = "function-syntax" > VariableSubjects::get_initial_value_inference< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > inf< / span > < span class = "plain-syntax" > ) < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < a href = "5-pi.html#SP7" class = "function-link" > < span class = "function-syntax" > PropertyInferences::get_value< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > inf< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Specifications::new_UNKNOWN< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > EMPTY_WORDING< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > VariableSubjects::origin_of_initial_value< / 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" > VariableSubjects::origin_of_initial_value< / span > < / span > :< br / > < a href = "4-vs.html#SP4" > § 4< / a > , < a href = "4-vs.html#SP4_1" > § 4.1< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > nonlocal_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > inference< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > inf< / span > < span class = "plain-syntax" > = < / span > < a href = "4-vs.html#SP2" class = "function-link" > < span class = "function-syntax" > VariableSubjects::get_initial_value_inference< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > inf< / span > < span class = "plain-syntax" > ) < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < a href = "5-inf.html#SP3" class = "function-link" > < span class = "function-syntax" > Inferences::where_inferred< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > inf< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > NULL< / 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" > VariableSubjects::has_initial_value_set< / 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" > VariableSubjects::has_initial_value_set< / span > < / span > :< br / > < a href = "4-vs.html#SP4" > § 4< / a > , < a href = "4-vs.html#SP4_1" > § 4.1< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > nonlocal_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nlv< / 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" > nlv< / span > < span class = "plain-syntax" > ) & & (< / span > < a href = "4-vs.html#SP2" class = "function-link" > < span class = "function-syntax" > VariableSubjects::origin_of_initial_value< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / 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 = "SP3" class = "paragraph-anchor" > < / a > < b > § 3. < / b > Initial values are typechecked twice: once when the assertions machinery
actually generates them (see < a href = "../assertions-module/4-pk.html" class = "internal" > Property Knowledge (in assertions)< / a > ) and then
again at model completion time. This looks wasteful — why not typecheck them
just the once, at completion time?
< / p >
< p class = "commentary" > The reason we don't is that the initial check produces more specific problem
messages, earlier on. For example, if we have:
< / p >
< blockquote >
< p > The tally is a number that varies. The tally is the Entire Game.< / p >
< / blockquote >
< p class = "commentary" > At model-checking time we would detect this as a problematic comparison
between "tally" and "Entire Game", and the problem message will thus be
slightly vague, and not make clear that Inform realises we were trying to set
a variable.
< / p >
< p class = "commentary" > On the other hand, we can't only do the initial check, because when assertions
are being worked through, some objects still have uncertain kinds.< sup id = "fnref:1" > < a href = "#fn:1" rel = "footnote" > 1< / a > < / sup > So we
perform only a weaker test at assertion time, and a full-strength test at
model-checking time.
< / p >
< ul class = "footnotetexts" > < li class = "footnote" id = "fn:1" > < p class = "inwebfootnote" > < sup id = "fnref:1" > < a href = "#fn:1" rel = "footnote" > 1< / a > < / sup > For example, it may not be known whether something containing something else
is a "container" or a "room". Assigning that object to a variable whose kind
is "room" would therefore be uncheckable at assertion time.
< a href = "#fnref:1" title = "return to text" > ↩ < / a > < / p > < / li > < / ul >
< pre class = "displayed-code all-displayed-code code-font" >
< span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > VariableSubjects::typecheck_initial_value< / 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" > VariableSubjects::typecheck_initial_value< / span > < / span > :< br / > < a href = "4-vs.html#SP4" > § 4< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > nonlocal_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > val< / 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" > model_checking_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" > nlv< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > internal_error< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "tried to initialise null variable"< / span > < span class = "plain-syntax" > );< / span >
2021-05-10 11:31:35 +03:00
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > kind< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > = < / span > < a href = "2-nv.html#SP9" class = "function-link" > < span class = "function-syntax" > NonlocalVariables::kind< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > );< / span >
2021-02-12 15:33:19 +02:00
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > kind< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > constant_kind< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > Specifications::to_kind< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > val< / span > < span class = "plain-syntax" > );< / span >
2022-04-14 00:09:08 +03:00
< span class = "plain-syntax" > < / span > < span class = "named-paragraph-container code-font" > < a href = "4-vs.html#SP3_1" class = "named-paragraph-link" > < span class = "named-paragraph" > Cast the empty list to whatever kind of list is expected< / span > < span class = "named-paragraph-number" > 3.1< / span > < / a > < / span > < span class = "plain-syntax" > ;< / span >
2021-02-12 15:33:19 +02:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > outcome< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > Kinds::compatible< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > constant_kind< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > );< / span >
2021-03-05 18:20:09 +02:00
2021-02-12 15:33:19 +02:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > throw_problem< / 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" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > outcome< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NEVER_MATCH< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > throw_problem< / 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" > if< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > model_checking_stage< / span > < span class = "plain-syntax" > ) & & (< / span > < span class = "identifier-syntax" > outcome< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > SOMETIMES_MATCH< / span > < span class = "plain-syntax" > )) < / span > < span class = "identifier-syntax" > throw_problem< / 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" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > throw_problem< / span > < span class = "plain-syntax" > )< / span >
2022-04-14 00:09:08 +03:00
< span class = "plain-syntax" > < / span > < span class = "named-paragraph-container code-font" > < a href = "4-vs.html#SP3_2" class = "named-paragraph-link" > < span class = "named-paragraph" > The value doesn't match the kind of the variable< / span > < span class = "named-paragraph-number" > 3.2< / span > < / a > < / span > < span class = "plain-syntax" > ;< / span >
2021-02-12 15:33:19 +02:00
< 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 >
< / pre >
2022-04-14 00:09:08 +03:00
< p class = "commentary firstcommentary" > < a id = "SP3_1" class = "paragraph-anchor" > < / a > < b > § 3.1. < / b > < span class = "named-paragraph-container code-font" > < span class = "named-paragraph-defn" > Cast the empty list to whatever kind of list is expected< / span > < span class = "named-paragraph-number" > 3.1< / 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" > if< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > Kinds::get_construct< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > constant_kind< / span > < span class = "plain-syntax" > ) == < / span > < span class = "identifier-syntax" > CON_list_of< / span > < span class = "plain-syntax" > ) & & < / span >
< span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Kinds::eq< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Kinds::unary_construction_material< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > constant_kind< / span > < span class = "plain-syntax" > ), < / span > < span class = "identifier-syntax" > K_nil< / span > < span class = "plain-syntax" > )) & & < / span >
< span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Lists::length_of_ll< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Node::get_text< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > val< / 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" > Kinds::get_construct< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > ) == < / span > < span class = "identifier-syntax" > CON_list_of< / span > < span class = "plain-syntax" > )) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Lists::set_kind_of_list_at< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Node::get_text< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > val< / span > < span class = "plain-syntax" > ), < / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Node::set_kind_of_value< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > val< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > constant_kind< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< / pre >
< ul class = "endnotetexts" > < li > This code is used in < a href = "4-vs.html#SP3" > § 3< / a > .< / li > < / ul >
< p class = "commentary firstcommentary" > < a id = "SP3_2" class = "paragraph-anchor" > < / a > < b > § 3.2. < / b > < span class = "named-paragraph-container code-font" > < span class = "named-paragraph-defn" > The value doesn't match the kind of the variable< / span > < span class = "named-paragraph-number" > 3.2< / span > < / span > < span class = "comment-syntax" > =< / span >
2021-02-12 15:33:19 +02:00
< / p >
< pre class = "displayed-code all-displayed-code code-font" >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > LOG< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "Variable: %u; constant: %u\n"< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > constant_kind< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::quote_source< / span > < span class = "plain-syntax" > (1, < / span > < span class = "identifier-syntax" > current_sentence< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::quote_wording< / span > < span class = "plain-syntax" > (2, < / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > name< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::quote_wording< / span > < span class = "plain-syntax" > (3, < / span > < span class = "identifier-syntax" > Node::get_text< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > val< / span > < span class = "plain-syntax" > ));< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::quote_kind< / span > < span class = "plain-syntax" > (4, < / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::quote_kind< / span > < span class = "plain-syntax" > (5, < / span > < span class = "identifier-syntax" > constant_kind< / 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" > Kinds::Behaviour::is_subkind_of_object< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > )) & & < / span >
< span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Rvalues::is_nothing_object_constant< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > val< / span > < span class = "plain-syntax" > ))) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > StandardProblems::handmade_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_QuantityKindNothing< / span > < span class = "plain-syntax" > ));< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::issue_problem_segment< / span > < span class = "plain-syntax" > (< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "The sentence %1 tells me that '%2', which should be %4 that varies, is to "< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "have the initial value 'nothing'. This is allowed as an 'object which varies', "< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "but the rules are stricter for %4."< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::issue_problem_end< / 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" > StandardProblems::handmade_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_GlobalKindWrong< / span > < span class = "plain-syntax" > ));< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::issue_problem_segment< / span > < span class = "plain-syntax" > (< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "The sentence %1 tells me that '%2', which is %4 that varies, "< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "should start out with the value '%3', but this is %5 and not %4."< / 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" > Kinds::Behaviour::is_object< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > constant_kind< / span > < span class = "plain-syntax" > )) & & < / span >
< span class = "plain-syntax" > (!< / span > < span class = "identifier-syntax" > Kinds::Behaviour::is_object< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > kind_as_declared< / span > < span class = "plain-syntax" > )))< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::issue_problem_segment< / span > < span class = "plain-syntax" > (< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > " %PIn sentences like this, when I can't understand some text, "< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "I often assume that it's meant to be a new object. So it may "< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "be that you intended '%3' to be something quite different, "< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "but I just didn't get it."< / span > < span class = "plain-syntax" > );< / span >
2022-05-05 01:23:12 +03:00
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > UsingProblems::diagnose_further< / span > < span class = "plain-syntax" > ();< / span >
2021-02-12 15:33:19 +02:00
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::issue_problem_end< / 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 >
< / pre >
< ul class = "endnotetexts" > < li > This code is used in < a href = "4-vs.html#SP3" > § 3< / a > .< / li > < / ul >
< p class = "commentary firstcommentary" > < a id = "SP4" class = "paragraph-anchor" > < / a > < b > § 4. < / b > At model-checking stage, we give variables their initial values. Note
that the < a href = "../assertions-module/4-pk.html" class = "internal" > Property Knowledge (in assertions)< / a > code will throw problem
messages if these have the wrong kind, so we don't need to.
< / 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" > VariableSubjects::check_model< / 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" > VariableSubjects::check_model< / span > < / span > :< br / > < a href = "4-vs.html#SP1" > § 1< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > inference_subject_family< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > family< / span > < span class = "plain-syntax" > ,< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > inference_subject< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > infs< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > nonlocal_variable< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > = < / span > < a href = "4-vs.html#SP1" class = "function-link" > < span class = "function-syntax" > VariableSubjects::to_variable< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > infs< / 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" > nlv< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "named-paragraph-container code-font" > < a href = "4-vs.html#SP4_1" class = "named-paragraph-link" > < span class = "named-paragraph" > Verify that externally-stored nonlocals haven't been initialised< / span > < span class = "named-paragraph-number" > 4.1< / span > < / a > < / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > current_sentence< / span > < span class = "plain-syntax" > = < / span > < a href = "4-vs.html#SP2" class = "function-link" > < span class = "function-syntax" > VariableSubjects::origin_of_initial_value< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < a href = "4-vs.html#SP2" class = "function-link" > < span class = "function-syntax" > VariableSubjects::has_initial_value_set< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > )) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > parse_node< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > init< / span > < span class = "plain-syntax" > = < / span > < a href = "4-vs.html#SP2" class = "function-link" > < span class = "function-syntax" > VariableSubjects::get_initial_value< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < a href = "4-vs.html#SP3" class = "function-link" > < span class = "function-syntax" > VariableSubjects::typecheck_initial_value< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > init< / 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 = "plain-syntax" > }< / span >
< / pre >
< p class = "commentary firstcommentary" > < a id = "SP4_1" class = "paragraph-anchor" > < / a > < b > § 4.1. < / b > If a variable is said to be the same as, say, < span class = "extract" > < span class = "extract-syntax" > my_var< / span > < / span > defined in some kit
of Inter code somewhere out of our reach, then it makes no sense to allow the
source text to specify its initial value — the initial value is whatever
that faraway Inter code said it was.
< / p >
< p class = "commentary" > < span class = "named-paragraph-container code-font" > < span class = "named-paragraph-defn" > Verify that externally-stored nonlocals haven't been initialised< / span > < span class = "named-paragraph-number" > 4.1< / span > < / span > < span class = "comment-syntax" > =< / span >
< / p >
< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > RTVariables::is_initialisable< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / 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" > nlv< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > alias_subject< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) & & < / span >
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< span class = "plain-syntax" > (< / span > < a href = "4-vs.html#SP2" class = "function-link" > < span class = "function-syntax" > VariableSubjects::has_initial_value_set< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > ))) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > current_sentence< / span > < span class = "plain-syntax" > = < / span > < a href = "4-vs.html#SP2" class = "function-link" > < span class = "function-syntax" > VariableSubjects::origin_of_initial_value< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::quote_source< / span > < span class = "plain-syntax" > (1, < / span > < span class = "identifier-syntax" > current_sentence< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::quote_wording< / span > < span class = "plain-syntax" > (2, < / span > < span class = "identifier-syntax" > nlv< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > name< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > StandardProblems::handmade_problem< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > Task::syntax_tree< / span > < span class = "plain-syntax" > (),< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > _p_< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > PM_InaccessibleVariable< / span > < span class = "plain-syntax" > ));< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::issue_problem_segment< / span > < span class = "plain-syntax" > (< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "The sentence %1 tells me that '%2' has a specific initial value, "< / span >
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< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "but this is a variable which has been translated into an Inter variable "< / span >
< span class = "plain-syntax" > < / span > < span class = "string-syntax" > "defined in a kit. Any initial value must be given there, and not here."< / span > < span class = "plain-syntax" > );< / span >
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< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > Problems::issue_problem_end< / span > < span class = "plain-syntax" > ();< / span >
< span class = "plain-syntax" > }< / span >
< / pre >
< ul class = "endnotetexts" > < li > This code is used in < a href = "4-vs.html#SP4" > § 4< / a > .< / li > < / ul >
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