To manage the different types of packages emitted by Inform.

• §1. Package types

§1. Package types. Inter code is a nested hierarchy of "packages", which can be assigned "types". Inter requires two types to exist, _plain and _code, and leaves the rest to the user (i.e., us) to define as we see fit. In fact Inform generates packages of slightly over 50 different types.

At run time, package types are pointers to the inter symbol which defined them, but this is not a convenient way to refer to them in the Inform source code. Instead we use the following function:

inter_symbol *PackageTypes::get?Usage of PackageTypes::get:
§2
Building Site - §2
Hierarchy Locations - §3, §4, §5
Packaging - §11, §14, §17, §19
Producing Inter - §3(inter_tree *I, text_stream *name) {
    inter_symbols_table *scope = InterTree::global_scope(I);

    inter_symbol *ptype = InterSymbolsTables::symbol_from_name(scope, name);
    if (ptype == NULL) {
        int enclose = TRUE;
        Decide if this package type is to be enclosing1.1;
        ptype = Produce::new_symbol(scope, name);
        Produce::guard(Inter::PackageType::new_packagetype(
            Site::package_types(I), ptype,
            0, NULL));
        if (enclose) Produce::annotate_symbol_i(ptype, ENCLOSING_IANN, 1);
    }
    return ptype;
}

§1.1. Most package types are "enclosing". Suppose that Inform is compiling something to go into the package, but finds that it needs to compile something else in order to do so — for example, it's compiling code to set a variable to be equal to a literal piece of text, which must itself be compiled as a small array. Where does Inform put that array? If the current package is "enclosing", then Inform puts it into the package itself; and if not, then into the package holding the current package, if that in turn is "enclosing"; and so on.

It seems tidy to make all packages enclosing, and in fact (after much experiment) Inform nearly does that. But _code packages have to be an exception, because the Inter specification doesn't allow constants (and therefore arrays) to be defined inside _code packages.

Decide if this package type is to be enclosing1.1 =

    if (Str::eq(name, I"_code")) enclose = FALSE;

• This code is used in §1.

§2. Symbol lookups by name are fast, but not instant, so we might some day want to optimise this by cacheing the result:

inter_symbol *PackageTypes::function?Usage of PackageTypes::function:
Packaging - §18(inter_tree *I) {
    return PackageTypes::get(I, I"_function");
}