82 lines
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82 lines
90 KiB
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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>5.6 Structure Utilities</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="tocviewselflink" 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="tocviewlink" 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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result vector contains a symbol whose printed name has the form
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<span class="RktSym">struct:</span><span class="RktVar">id</span>. Each remaining slot contains
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either the value of a field in <span class="RktVar">v</span>, if it is accessible via the
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current inspector, or <span class="RktVar">opaque-v</span> for a field that is not
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accessible. A single <span class="RktVar">opaque-v</span> value is used in the vector for
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contiguous inaccessible fields. (Consequently, the size of the vector
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does not match the size of the <span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span> if more than one field
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is inaccessible.)</div></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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._struct~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">struct?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara"> Returns <span class="RktVal">#t</span> if
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<span class="RktSym"><a href="inspectors.html#%28def._%28%28quote._~23~25kernel%29._struct-info%29%29" class="RktValLink" data-pltdoc="x">struct-info</a></span> exposes any structure types of <span class="RktVar">v</span> with
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the current inspector, <span class="RktVal">#f</span> otherwise.</div></p><p>Typically, when <span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct~3f%29%29" class="RktValLink" data-pltdoc="x">struct?</a></span><span class="stt"> </span><span class="RktVar">v</span><span class="RktPn">)</span> is true, then
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<span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct-~3evector%29%29" class="RktValLink" data-pltdoc="x">struct->vector</a></span><span class="stt"> </span><span class="RktVar">v</span><span class="RktPn">)</span> exposes at least one field value. It is
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possible, however, for the only visible types of <span class="RktVar">v</span> to
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contribute zero fields.</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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._struct-type~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct-type~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">struct-type?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if
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<span class="RktVar">v</span> is a structure type descriptor value, <span class="RktVal">#f</span>
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otherwise.</div></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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._struct-constructor-procedure~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct-constructor-procedure~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">struct-constructor-procedure?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns
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<span class="RktVal">#t</span> if <span class="RktVar">v</span> is a constructor procedure generated by
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<span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span> or <span class="RktSym"><a href="creatingmorestructs.html#%28def._%28%28quote._~23~25kernel%29._make-struct-type%29%29" class="RktValLink" data-pltdoc="x">make-struct-type</a></span>, <span class="RktVal">#f</span>
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otherwise.</div></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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._struct-predicate-procedure~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct-predicate-procedure~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">struct-predicate-procedure?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns
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<span class="RktVal">#t</span> if <span class="RktVar">v</span> is a predicate procedure generated by
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<span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span> or <span class="RktSym"><a href="creatingmorestructs.html#%28def._%28%28quote._~23~25kernel%29._make-struct-type%29%29" class="RktValLink" data-pltdoc="x">make-struct-type</a></span>, <span class="RktVal">#f</span>
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otherwise.</div></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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._struct-accessor-procedure~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct-accessor-procedure~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">struct-accessor-procedure?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns
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<span class="RktVal">#t</span> if <span class="RktVar">v</span> is an accessor procedure generated by
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<span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span>, <span class="RktSym"><a href="creatingmorestructs.html#%28def._%28%28quote._~23~25kernel%29._make-struct-type%29%29" class="RktValLink" data-pltdoc="x">make-struct-type</a></span>, or
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<span class="RktSym"><a href="creatingmorestructs.html#%28def._%28%28quote._~23~25kernel%29._make-struct-field-accessor%29%29" class="RktValLink" data-pltdoc="x">make-struct-field-accessor</a></span>, <span class="RktVal">#f</span> otherwise.</div></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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._struct-mutator-procedure~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct-mutator-procedure~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">struct-mutator-procedure?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns
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<span class="RktVal">#t</span> if <span class="RktVar">v</span> is a mutator procedure generated by
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<span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span>, <span class="RktSym"><a href="creatingmorestructs.html#%28def._%28%28quote._~23~25kernel%29._make-struct-type%29%29" class="RktValLink" data-pltdoc="x">make-struct-type</a></span>, or
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<span class="RktSym"><a href="creatingmorestructs.html#%28def._%28%28quote._~23~25kernel%29._make-struct-field-mutator%29%29" class="RktValLink" data-pltdoc="x">make-struct-field-mutator</a></span>, <span class="RktVal">#f</span> otherwise.</div></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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._prefab-struct-key))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._prefab-struct-key%29%29" class="RktValDef RktValLink" data-pltdoc="x">prefab-struct-key</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._list~3f%29%29" class="RktValLink" data-pltdoc="x">list?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#f</span> if <span class="RktVar">v</span> is not an instance of a
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<a href="structures.html#%28tech._prefab%29" class="techoutside" data-pltdoc="x"><span class="techinside">prefab</span></a> structure type. Otherwise, the result is the shorted key
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that could be used with <span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._make-prefab-struct%29%29" class="RktValLink" data-pltdoc="x">make-prefab-struct</a></span> to create an instance
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of the structure type.</div></p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._prefab-struct-key%29%29" class="RktValLink" data-pltdoc="x">prefab-struct-key</a></span><span class="hspace"> </span><span class="RktVal">#s</span><span class="RktVal">(</span><span class="RktVal">cat</span><span class="hspace"> </span><span class="RktVal">"Garfield"</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'cat</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym">cat</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">name</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym">cute-cat</span><span class="hspace"> </span><span class="RktSym">cat</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">shipping-dest</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">cute-cat</span><span class="hspace"> </span><span class="RktVal">"Nermel"</span><span class="hspace"> </span><span class="RktVal">"Abu Dhabi"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'#s((cute-cat cat 1) "Nermel" "Abu Dhabi")</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._prefab-struct-key%29%29" class="RktValLink" data-pltdoc="x">prefab-struct-key</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">cute-cat</span><span class="hspace"> </span><span class="RktVal">"Nermel"</span><span class="hspace"> </span><span class="RktVal">"Abu Dhabi"</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(cute-cat cat 1)</span></p></td></tr></table></blockquote></div></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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._make-prefab-struct))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._make-prefab-struct%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-prefab-struct</a></span></span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct~3f%29%29" class="RktValLink" data-pltdoc="x">struct?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span
|
||
|
|
<span class="RktVar">v</span>s as field values. The <span class="RktVar">key</span> and the number of
|
||
|
|
<span class="RktVar">v</span>s determine the <a href="structures.html#%28tech._prefab%29" class="techoutside" data-pltdoc="x"><span class="techinside">prefab</span></a> structure type.</div></p><p>A <span class="RktVar">key</span> identifies a structure type based on a list with the
|
||
|
|
following items:</p><ul><li><p>A symbol for the structure type’s name.</p></li><li><p>An exact, nonnegative integer representing the number of
|
||
|
|
non-automatic fields in the structure type, not counting fields
|
||
|
|
from the supertype (if any).</p></li><li><p>A list of two items, where the first is an exact, nonnegative
|
||
|
|
integer for the number of automatic fields in the structure
|
||
|
|
type that are not from the supertype (if any), and the second
|
||
|
|
element is an arbitrary value that is the value for the
|
||
|
|
automatic fields.</p></li><li><p>A vector of exact, nonnegative integers that indicate mutable
|
||
|
|
non-automatic fields in the structure type, counting from
|
||
|
|
<span class="RktVal">0</span> and not including fields from the supertype (if
|
||
|
|
any).</p></li><li><p>Nothing else, if the structure type has no
|
||
|
|
supertype. Otherwise, the rest of the list is the key
|
||
|
|
for the supertype.</p></li></ul><p>An empty vector and an auto-field list that starts with <span class="RktVal">0</span> can
|
||
|
|
be omitted. Furthermore, the first integer (which indicates the number
|
||
|
|
of non-automatic fields) can be omitted, since it can be inferred from
|
||
|
|
the number of supplied <span class="RktVar">v</span>s. Finally, a single symbol can be
|
||
|
|
used instead of a list that contains only a symbol (in the case that
|
||
|
|
the structure type has no supertype, no automatic fields, and no
|
||
|
|
mutable fields).</p><p>The total field count must be no more than 32768. If the number of
|
||
|
|
fields indicated by <span class="RktVar">key</span> is inconsistent with the number of
|
||
|
|
supplied <span class="RktVar">v</span>s, the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._make-prefab-struct%29%29" class="RktValLink" data-pltdoc="x">make-prefab-struct</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">clown</span><span class="hspace"> </span><span class="RktVal">"Binky"</span><span class="hspace"> </span><span class="RktVal">"pie"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'#s(clown "Binky" "pie")</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._make-prefab-struct%29%29" class="RktValLink" data-pltdoc="x">make-prefab-struct</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">clown</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">"Binky"</span><span class="hspace"> </span><span class="RktVal">"pie"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'#s(clown "Binky" "pie")</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._make-prefab-struct%29%29" class="RktValLink" data-pltdoc="x">make-prefab-struct</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">clown</span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">(</span><span class="RktVal">0</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">)</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">"Binky"</span><span class="hspace"> </span><span class="RktVal">"pie"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'#s(clown "Binky" "pie")</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._make-prefab-struct%29%29" class="RktValLink" data-pltdoc="x">make-prefab-struct</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">clown</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">(</span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">)</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">"Binky"</span><span class="hspace"> </span><span class="RktVal">"pie"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'#s((clown (1 #f)) "Binky" "pie")</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._make-prefab-struct%29%29" class="RktValLink" data-pltdoc="x">make-prefab-struct</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">c
|
||
|
|
the <a href="define-struct.html#%28tech._structure._type._descriptor%29" class="techoutside" data-pltdoc="x"><span class="techinside">structure type descriptor</span></a> <span class="RktVar">type</span> if it represents a
|
||
|
|
prefab structure type, <span class="RktVal">#f</span> otherwise.</div></p><p class="SHistory">Added in version 8.5.0.8 of package <span class="stt">base</span>.</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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._prefab-key-~3estruct-type))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._prefab-key-~3estruct-type%29%29" class="RktValDef RktValLink" data-pltdoc="x">prefab-key->struct-type</a></span></span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">field-count</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct-type~3f%29%29" class="RktValLink" data-pltdoc="x">struct-type?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._prefab-key~3f%29%29" class="RktValLink" data-pltdoc="x">prefab-key?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">field-count</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._integer-in%29%29" class="RktValLink" data-pltdoc="x">integer-in</a></span><span class="hspace"> </span><span class="RktVal">0</span><span class="hspace"> </span><span class="RktVal">32768</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a <a href="define-struct.html#%28tech._structure._type._descriptor%29" class="techoutside" data-pltdoc="x"><span class="techinside">structure type descriptor</span></a> for the <a href="structures.html#%28tech._prefab%29" class="techoutside" data-pltdoc="x"><span class="techinside">prefab</span></a>
|
||
|
|
structure type specified by the combination of <span class="RktVar">key</span> and
|
||
|
|
<span class="RktVar">field-count</span>.</div></p><p>If the number of fields indicated by <span class="RktVar">key</span> is inconsistent with
|
||
|
|
<span class="RktVar">field-count</span>, the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._prefab-key~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._prefab-key~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">prefab-key?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Return <span class="RktVal">#t</span> if <span class="RktVar">v</span> can be a <a href="structures.html#%28tech._prefab%29" class="techoutside" data-pltdoc="x"><span class="techinside">prefab</span></a> structure type
|
||
|
|
key, <span class="RktVal">#f</span> otherwise.</div></p><p>See <span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._make-prefab-struct%29%29" class="RktValLink" data-pltdoc="x">make-prefab-struct</a></span> for a description of valid key shapes.</p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""Additional_Structure_Utilities"">5.6.1<tt> </tt><a name="(part._.Additional_.Structure_.Utilities)"></a><a name="(mod-path._racket/struct)"></a>Additional Structure Utilities</h5><p><div class="SIntrapara"><table cellspacing="0" cellpadding="0" class="defmodule"><tr><td align="left"><span class="hspace"> </span><span class="RktPn">(</span><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><span class="stt"> </span><a href="structutils.html#%28mod-path._racket%2Fstruct%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/struct</span></a><span class="RktPn">)</span></td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <a href="https://pkgs.racket-lang.org/package/base" title="Install this package using `raco pkg install base`"><span class="stt">base</span></a></span></td></tr></table></div><div class="SIntrapara">The bindings documented in this section are provided by the <a href="structutils.html#%28mod-path._racket%2Fstruct%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/struct</span></a> library, not <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/base</span></a> or <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket</span></a>.</div></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>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((lib._racket/struct..rkt)._make-constructor-style-printer))"></a><span title="Provided from: racket/struct | Package: base"><span class="RktSym"><a href="structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._make-constructor-style-printer%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-constructor-style-printer</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">get-constructor</span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">get-contents</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._output-port~3f%29%29" class="RktValLink" data-pltdoc="x">output-port?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktVal">#t</span><span clas
|
||
|
|
<span class="RktSym"><a href="Printer_Extension.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3acustom-write%29%29" class="RktValLink" data-pltdoc="x">gen:custom-write</a></span> or <span class="RktSym"><a href="Printer_Extension.html#%28def._%28%28quote._~23~25kernel%29._prop~3acustom-write%29%29" class="RktValLink" data-pltdoc="x">prop:custom-write</a></span>.
|
||
|
|
The function prints values in “constructor style.” When
|
||
|
|
the value is <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._print%29%29" class="RktValLink" data-pltdoc="x">print</a></span>ed as an expression, it is shown
|
||
|
|
as an application of the constructor (as returned by
|
||
|
|
<span class="RktVar">get-constructor</span>) to the contents (as returned by
|
||
|
|
<span class="RktVar">get-contents</span>). When given to <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._write%29%29" class="RktValLink" data-pltdoc="x">write</a></span>, it is
|
||
|
|
shown as an unreadable value with the constructor separated
|
||
|
|
from the contents by a colon.</div></p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym">point</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">x</span><span class="hspace"> </span><span class="RktSym">y</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">#:methods</span><span class="hspace"> </span><span class="RktSym"><a href="Printer_Extension.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3acustom-write%29%29" class="RktValLink" data-pltdoc="x">gen:custom-write</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">write-proc</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._make-constructor-style-printer%29%29" class="RktValLink" data-pltdoc="x">make-constructor-style-printer</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">obj</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">point</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">obj</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29" class="RktValLink" data-pltdoc="x">list</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">point-x</span><span class="hspace"> </span><span class="RktSym">obj</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">point-y</span><span class="hspace"> </span><span class="RktSym">obj</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._print%29%29" class="RktValLink" data-pltdoc="x">print</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">point</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="RktPn">)</span></td></t
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<span class="RktSym"><a href="Printer_Extension.html#%28def._%28%28quote._~23~25kernel%29._prop~3acustom-print-quotable%29%29" class="RktValLink" data-pltdoc="x">prop:custom-print-quotable</a></span>, to determine whether a struct
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instance is quotable. If so, the printer may print it in
|
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<span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._write%29%29" class="RktValLink" data-pltdoc="x">write</a></span> mode it in certain contexts, such as within a list. For
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example:
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</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._print%29%29" class="RktValLink" data-pltdoc="x">print</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29" class="RktValLink" data-pltdoc="x">list</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">point</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">point</span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">4</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktOut">'(#<point: 1 2> #<point: 3 4>)</span></p></td></tr></table></blockquote></div><div class="SIntrapara">Use <span class="RktPn">#:property</span><span class="stt"> </span><span class="RktSym"><a href="Printer_Extension.html#%28def._%28%28quote._~23~25kernel%29._prop~3acustom-print-quotable%29%29" class="RktValLink" data-pltdoc="x">prop:custom-print-quotable</a></span><span class="stt"> </span><span class="RktVal">'</span><span class="RktVal">never</span> to prevent a
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struct instance from being considered quotable. For example:
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</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym">point2</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">x</span><span class="hspace"> </span><span class="RktSym">y</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">#:property</span><span class="hspace"> </span><span class="RktSym"><a href="Printer_Extension.html#%28def._%28%28quote._~23~25kernel%29._prop~3acustom-print-quotable%29%29" class="RktValLink" data-pltdoc="x">prop:custom-print-quotable</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">never</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">#:methods</span><span class="hspace"> </span><span class="RktSym"><a href="Printer_Extension.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3acustom-write%29%29" class="RktValLink" data-pltdoc="x">gen:custom-write</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">write-proc</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._make-constructor-style-printer%29%29" class="RktValLink" data-pltdoc="x">make-constructor-style-printer</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">obj</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">point</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">obj</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29" class="RktValLink" data-pltdoc="x">list</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">point2-x</span><span class="hspace"> </span><span class="RktSym">obj</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">point2-y</span><span class="hspace"> </span><span class="RktSym">obj</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.h
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fields. Unlike <span class="RktSym"><a href="structutils.html#%28def._%28%28quote._~23~25kernel%29._struct-~3evector%29%29" class="RktValLink" data-pltdoc="x">struct->vector</a></span>, the struct name itself is not
|
||
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included.</div></p><p>If any fields of <span class="RktVar">v</span> are inaccessible via the current inspector
|
||
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the behavior of <span class="RktSym"><a href="structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._struct-~3elist%29%29" class="RktValLink" data-pltdoc="x">struct->list</a></span> is determined by
|
||
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<span class="RktVar">on-opaque</span>. If <span class="RktVar">on-opaque</span> is <span class="RktVal">'</span><span class="RktVal">error</span> (the
|
||
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default), an error is raised. If it is <span class="RktVal">'</span><span class="RktVal">return-false</span>,
|
||
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<span class="RktSym"><a href="structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._struct-~3elist%29%29" class="RktValLink" data-pltdoc="x">struct->list</a></span> returns <span class="RktVal">#f</span>. If it is <span class="RktVal">'</span><span class="RktVal">skip</span>,
|
||
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the inaccessible fields are omitted from the list.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._open%29%29" class="RktStxLink" data-pltdoc="x">open</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">u</span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._struct-~3elist%29%29" class="RktValLink" data-pltdoc="x">struct->list</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._open%29%29" class="RktStxLink" data-pltdoc="x">open</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">b</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(a b)</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._struct-~3elist%29%29" class="RktValLink" data-pltdoc="x">struct->list</a></span><span class="hspace"> </span><span class="RktVal">#s</span><span class="RktVal">(</span><span class="RktVal">pre</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">3</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(1 2 3)</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym">secret</span><span class="hspace"> </span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._open%29%29" class="RktStxLink" data-pltdoc="x">open</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">x</span><span class="hspace"> </span><span class="RktSym">y</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._struct-~3elist%29%29" class="RktValLink" data-pltdoc="x">struct->list</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">secret</span><span class="hspace"> </span><span class="RktVal">0</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">17</span><span class="hspace"> </span><span class="RktVal">22</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">struct->list: expected argument of type <non-opaque struct>;</span></p></td></tr><tr><td><p><span class="RktErr">given: (secret 0 1 ...)</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="structutils.html#%28def._%28%28lib._racket%2Fstruct..rkt%29._struct-~
|