96 lines
3.3 KiB
Racket
96 lines
3.3 KiB
Racket
#reader(lib "docreader.ss" "scribble")
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@require[(lib "manual.ss" "scribble")]
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@require[(lib "eval.ss" "scribble")]
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@require["guide-utils.ss"]
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@title[#:tag "guide:module-provide"]{Exports: @scheme[provide]}
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By default, all of a module's definitions are private to the
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module. The @scheme[provide] form specifies definitions to be made
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available where the module is @scheme[require]d.
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@specform[(provide provide-spec ...)]{}
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A @scheme[provide] form can only appear at @tech{module level}.
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Specifying multiple @scheme[_provide-spec]s in a single
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@scheme[require] is exactly the same as using multiple
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@scheme[provide]s each with a single @scheme[_provide-spec].
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Each identifier can be exported at most once from a module across all
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@scheme[provide]s within the module. More precisely, the external name
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for each export must be distinct; the same internal binding can be
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exported multiple times with different external names.
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The allowed shape of a @scheme[_provide-spec] is defined recursively:
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@;------------------------------------------------------------------------
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@specspecsubform[identifier]{
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In its simplest form, a @scheme[_provide-spec] indicates a binding
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within its module to be exported. The binding can be from either a
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local definition, or from an import.
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}
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@;------------------------------------------------------------------------
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@specspecsubform[#:literals(rename)
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(rename [orig-id export-id] ...)]{
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A @scheme[rename] form is similar to just specifying an identifier,
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but the exported binding @scheme[orig-id] is given a different name,
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@scheme[export-id], to importing modules.
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}
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@;------------------------------------------------------------------------
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@specspecsubform[#:literals(all-defined)
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(all-defined)]{
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The @scheme[all-defined] shorthand exports all bindings that are
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defined within the exporting module (as opposed to imported).
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Use of the @scheme[all-defined] shorthand is generally discouraged,
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because it makes less clear the actual exports for a module, and
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because PLT Scheme programmers get into the habit of thinking that
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definitions can be added freely to a module without affecting its
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public interface.
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}
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@;------------------------------------------------------------------------
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@specspecsubform[#:literals(all-from)
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(all-from module-path)]{
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The @scheme[all-from] shorthand exports all bindings in the module
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that were imported using a @scheme[_require-spec] that is based on
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@scheme[module-path].
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Although different @scheme[module-path]s could refer to the same
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file-based module, re-exporting with @scheme[all-from] is based
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specifically on the @scheme[module-path] reference, and not the module
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that is actually referenced.
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}
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@;------------------------------------------------------------------------
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@specspecsubform[#:literals(except)
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(except provide-spec id ...)]{
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Like @scheme[provide-spec], but omitting the export of each
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@scheme[id], where @scheme[id] is the external name of the binding to
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omit.
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}
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@;------------------------------------------------------------------------
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@specspecsubform[#:literals(prefix)
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(prefix provide-spec prefix-id)]{
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Like @scheme[provide-spec], but adding @scheme[prefix-id] to the
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beginning of the external name for each exported binding.
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}
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