61 lines
2.5 KiB
Racket
61 lines
2.5 KiB
Racket
#lang scribble/doc
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@(require "mz.ss")
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@title[#:tag "modprotect"]{Code Inspectors}
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In the same way that inspectors control access to structure fields
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(see @secref["inspectors"]), inspectors also control access to
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@tech{module bindings}. The default inspector for @tech{module
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bindings} is determined by the @scheme[current-code-inspector]
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parameter, instead of the @scheme[current-inspector] parameter.
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When a @scheme[module] declaration is evaluated, the value of the
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@scheme[current-code-inspector] parameter is associated with the
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module declaration. When the module is invoked via @scheme[require] or
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@scheme[dynamic-require], a sub-inspector of the module's
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declaration-time inspector is created, and this sub-inspector is
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associated with the module invocation. Any inspector that controls the
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sub-inspector (i.e., the declaration-time inspector and its superior)
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controls the module invocation.
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Control over a module invocation enables
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@itemize{
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@item{the use of @scheme[module->namespace] on the module;}
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@item{access to the module's protected identifiers, i.e. those
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identifiers exported from the module with @scheme[protect]; and}
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@item{access to the module's protected and unexported variables
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within compiled code from @scheme[read] (see @scheme[current-compile]).}
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}
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If the value of @scheme[current-code-inspector] never changes, then no
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control is lost for any module invocation, since the module's
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invocation is associated with a sub-inspector of
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@scheme[current-code-inspector].
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The inspector for a module invocation is specific to a particular
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module registry, in case a module is attached to a new registry via
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@scheme[namespace-attach-module]. The invocation inspector in a
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particular registry can be changed via
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@scheme[namespace-unprotect-module] (but changing the inspector
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requires control over the old one).
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Control over a module declaration (as opposed to a mere invocation)
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enables the reconstruction of syntax objects that contain references
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to the module's unexported identifiers. Otherwise, the compiler and
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macro expander prevent any reference to an unexported identifier,
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unless the reference appears within an expression that was generated
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by the module's macros (or, more precisely, a macro from a module
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whose declaration inspector controls the invocation of the
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identifier's module). See @secref["stxcerts"] for further
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information.
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@defparam[current-code-inspector insp inspector?]{
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A parameter that determines an inspector to control access to module
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bindings and redefinitions.}
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