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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>14.10 Code Inspectors</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x">The Racket Reference</a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewselflink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class="
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(see <a href="inspectors.html" data-pltdoc="x">Structure Inspectors</a>), inspectors also control access to
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<a href="syntax-model.html#%28tech._module._binding%29" class="techoutside" data-pltdoc="x"><span class="techinside">module bindings</span></a>. Inspectors used this way are <a name="(tech._code._inspector)"></a><span style="font-style: italic">code
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inspectors</span>. The default code inspector for <a href="syntax-model.html#%28tech._module._binding%29" class="techoutside" data-pltdoc="x"><span class="techinside">module
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bindings</span></a> is determined by the <span class="RktSym"><a href="modprotect.html#%28def._%28%28quote._~23~25kernel%29._current-code-inspector%29%29" class="RktValLink" data-pltdoc="x">current-code-inspector</a></span>
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parameter, instead of the <span class="RktSym"><a href="inspectors.html#%28def._%28%28quote._~23~25kernel%29._current-inspector%29%29" class="RktValLink" data-pltdoc="x">current-inspector</a></span> parameter.</p><p>When a <span class="RktSym"><a href="module.html#%28form._%28%28quote._~23~25kernel%29._module%29%29" class="RktStxLink" data-pltdoc="x">module</a></span> declaration is evaluated, the value of the
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<span class="RktSym"><a href="modprotect.html#%28def._%28%28quote._~23~25kernel%29._current-code-inspector%29%29" class="RktValLink" data-pltdoc="x">current-code-inspector</a></span> parameter is associated with the
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module declaration. When the module is invoked via <span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span> or
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<span class="RktSym"><a href="Module_Names_and_Loading.html#%28def._%28%28quote._~23~25kernel%29._dynamic-require%29%29" class="RktValLink" data-pltdoc="x">dynamic-require</a></span>, 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 (including the declaration-time inspector and its
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superior) controls the module invocation. In particular, if the value
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of <span class="RktSym"><a href="modprotect.html#%28def._%28%28quote._~23~25kernel%29._current-code-inspector%29%29" class="RktValLink" data-pltdoc="x">current-code-inspector</a></span> never changes, then no control is
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lost for any module invocation, since the module’s invocation is
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associated with a sub-inspector of <span class="RktSym"><a href="modprotect.html#%28def._%28%28quote._~23~25kernel%29._current-code-inspector%29%29" class="RktValLink" data-pltdoc="x">current-code-inspector</a></span>.</p><p>When an inspector that controls a module invocation is installed with
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<span class="RktSym"><a href="modprotect.html#%28def._%28%28quote._~23~25kernel%29._current-code-inspector%29%29" class="RktValLink" data-pltdoc="x">current-code-inspector</a></span>, it enables using
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<span class="RktSym"><a href="Namespaces.html#%28def._%28%28quote._~23~25kernel%29._module-~3enamespace%29%29" class="RktValLink" data-pltdoc="x">module->namespace</a></span> on the module, and it enables access to the
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module’s <a name="(tech._protected)"></a><span style="font-style: italic">protected</span> exports (i.e., those identifiers exported from the
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module with <span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._protect-out%29%29" class="RktStxLink" data-pltdoc="x">protect-out</a></span>) via <span class="RktSym"><a href="Module_Names_and_Loading.html#%28def._%28%28quote._~23~25kernel%29._dynamic-require%29%29" class="RktValLink" data-pltdoc="x">dynamic-require</a></span>. A
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module cannot <span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span> a module that has a weaker
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declaration-time code inspector.</p><p>When a <span class="RktSym"><a href="module.html#%28form._%28%28quote._~23~25kernel%29._module%29%29" class="RktStxLink" data-pltdoc="x">module</a></span> form is expanded or a <a href="syntax-model.html#%28tech._namespace%29" class="techoutside" data-pltdoc="x"><span class="techinside">namespace</span></a> is
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created, the value of <span class="RktSym"><a href="modprotect.html#%28def._%28%28quote._~23~25kernel%29._current-code-inspector%29%29" class="RktValLink" data-pltdoc="x">current-code-inspector</a></span> is associated
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with the module or namespace’s top-level <a href="syntax-model.html#%28tech._lexical._information%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexical information</span></a>.
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Syntax objects with that <a href="syntax-model.html#%28tech._lexical._information%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexical information</span></a> gain access to the
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protected and unexported bindings of any module that the inspector
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controls. In the case of a <span class="RktSym"><a href="module.html#%28form._%28%28quote._~23~25kernel%29._module%29%29" class="RktStxLink" data-pltdoc="x">module</a></span>, the inspector sticks with
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such syntax objects even the syntax object is used in the expansion of
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code in a less powerful context; furthermore, if the syntax object is
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an identifier that is compiled as a variable reference, the inspector
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sticks with the variable reference even if it appears in a module form
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that is evaluated (i.e., declared) with a weaker inspector. When a
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syntax object or variable reference is within compiled code that is
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printed (see <a href="printing.html#%28part._print-compiled%29" data-pltdoc="x">Printing Compiled Code</a>), the associated inspector is
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not preserved.</p><p>When compiled code in printed form is <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span> back in, no
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inspectors are associated with the code. When the code is
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<span class="RktSym"><a href="eval.html#%28def._%28%28quote._~23~25kernel%29._eval%29%29" class="RktValLink" data-pltdoc="x">eval</a></span>uated, the instantiated syntax-object literals and
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module-variable references acquire value of
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<span class="RktSym"><a href="modprotect.html#%28def._%28%28quote._~23~25kernel%29._current-code-inspector%29%29" class="RktValLink" data-pltdoc="x">current-code-inspector</a></span> as their inspector.</p><p>When a module instantiation is attached to multiple <a href="syntax-model.html#%28tech._namespace%29" class="techoutside" data-pltdoc="x"><span class="techinside">namespaces</span></a>,
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each with its own <a href="syntax-model.html#%28tech._module._registry%29" class="techoutside" data-pltdoc="x"><span class="techinside">module registry</span></a>, the inspector for the module
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invocation can be registry-specific. The invocation inspector in a
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particular module registry can be changed via
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<span class="RktSym"><a href="Namespaces.html#%28def._%28%28quote._~23~25kernel%29._namespace-unprotect-module%29%29" class="RktValLink" data-pltdoc="x">namespace-unprotect-module</a></span> (but changing the inspector
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requires control over the old one).</p><p class="SHistory">Changed in version 8.1.0.8 of package <span class="stt">base</span>: Added constraint against
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<span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span> of a module with
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a weaker code inspector.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._current-code-inspector))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="modprotect.html#%28def._%28%28quote._~23~25kernel%29._current-code-inspector%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-code-inspector</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="inspectors.html#%28def._%28%28quote._~23~25kernel%29._inspector~3f%29%29" class="RktValLink" data-pltdoc="x">inspector?</a></span></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="modprotect.html#%28def._%28%28quote._~23~25kernel%29._current-code-inspector%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-code-inspector</a></span></span><span class="hspace"> </span><span class="RktVar">insp</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">insp</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="inspectors.html#%28def._%28%28quote._~23~25kernel%29._inspector~3f%29%29" class="RktValLink" data-pltdoc="x">inspector?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="eval-model.html#%28tech._parameter%29" class="techoutside" data-pltdoc="x"><span class="techinside">parameter</span></a> that determines an inspector to control access to
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module bindings and redefinitions.</div></p><p>If the code inspector is changed from its original value, then
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bytecode loaded by the default <a href="eval.html#%28tech._compiled._load._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">compiled-load handler</span></a> is marked
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as non-runnable.</p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="inspectors.html" title="backward to "14.9 Structure Inspectors"" data-pltdoc="x">← prev</a> <a href="security.html" title="up to "14 Reflection and Security"" data-pltdoc="x">up</a> <a href="plumbers.html" title="forward to "14.11 Plumbers"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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