/usr/share/doc/racket/reference/struct-copy.html is in racket-doc 6.7-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><title>5.5 Copying and Updating Structures</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"><span style="font-weight: bold">The Racket Reference</span></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="tocviewlink" data-pltdoc="x">Running Racket</a></td></tr><tr><td align="right"></td><td><a href="doc-bibliography.html" class="tocviewlink" data-pltdoc="x">Bibliography</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">▼</a></td><td>5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">5.1 </td><td><a href="define-struct.html" class="tocviewlink" data-pltdoc="x">Defining Structure Types:<span class="mywbr"> </span> <span class="RktSym"><span class="RktStxLink">struct</span></span></a></td></tr><tr><td align="right">5.2 </td><td><a href="creatingmorestructs.html" class="tocviewlink" data-pltdoc="x">Creating Structure Types</a></td></tr><tr><td align="right">5.3 </td><td><a href="structprops.html" class="tocviewlink" data-pltdoc="x">Structure Type Properties</a></td></tr><tr><td align="right">5.4 </td><td><a href="struct-generics.html" class="tocviewlink" data-pltdoc="x">Generic Interfaces</a></td></tr><tr><td align="right">5.5 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Copying and Updating Structures</a></td></tr><tr><td align="right">5.6 </td><td><a href="structutils.html" class="tocviewlink" data-pltdoc="x">Structure Utilities</a></td></tr><tr><td align="right">5.7 </td><td><a href="structinfo.html" class="tocviewlink" data-pltdoc="x">Structure Type Transformer Binding</a></td></tr></table></div></div></div><div class="tocsub"><div class="tocsubtitle">On this page:</div><table class="tocsublist" cellspacing="0"><tr><td><a href="#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct-copy%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">struct-<wbr></wbr>copy</span></span></a></td></tr></table></div></div><div class="maincolumn"><div class="main"><div class="navsettop"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.7", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.7");">top</a></span><span class="navright"> <a href="struct-generics.html" title="backward to "5.4 Generic Interfaces"" data-pltdoc="x">← prev</a> <a href="structures.html" title="up to "5 Structures"" data-pltdoc="x">up</a> <a href="structutils.html" title="forward to "5.6 Structure Utilities"" data-pltdoc="x">next →</a></span> </div><h4 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""struct-copy"">5.5<tt> </tt><a name="(part._struct-copy)"></a>Copying and Updating Structures</h4><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>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._racket/private/base..rkt)._struct-copy))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct-copy%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">struct-copy</a></span></span><span class="hspace"> </span><span class="RktVar">id</span><span class="hspace"> </span><span class="RktVar">struct-expr</span><span class="hspace"> </span><span class="RktVar">fld-id</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="stt"> </span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="specgrammar"><tr><td align="right" valign="baseline"><span class="RktVar">fld-id</span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">=</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">[</span><span class="RktVar">field-id</span><span class="hspace"> </span><span class="RktVar">expr</span><span class="RktPn">]</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">[</span><span class="RktVar">field-id</span><span class="hspace"> </span><span class="RktPn">#:parent</span><span class="hspace"> </span><span class="RktVar">parent-id</span><span class="hspace"> </span><span class="RktVar">expr</span><span class="RktPn">]</span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Creates a new instance of the structure type <span class="RktVar">id</span> with the same
field values as the structure produced by <span class="RktVar">struct-expr</span>, except
that the value of each supplied <span class="RktVar">field-id</span> is instead
determined by the corresponding <span class="RktVar">expr</span>. If <span class="RktPn">#:parent</span>
is specified, the <span class="RktVar">parent-id</span> must be bound to a parent
structure type of <span class="RktVar">id</span>.</div></p><p>The <span class="RktVar">id</span> must have a <a href="syntax-model.html#%28tech._transformer%29" class="techoutside" data-pltdoc="x"><span class="techinside">transformer</span></a> binding that
encapsulates information about a structure type (i.e., like the
initial identifier bound by <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>), and the binding
must supply a constructor, a predicate, and all field accessors.</p><p>Each <span class="RktVar">field-id</span> is combined with <span class="RktVar">id</span>
(or <span class="RktVar">parent-id</span>, if present) to form
<span class="RktVar">id</span><span class="RktSym">-</span><span class="RktVar">field-id</span> (using the lexical
context of <span class="RktVar">field-id</span>), which must be one of the accessor
bindings in <span class="RktVar">id</span>. The accessor bindings determined by different
<span class="RktVar">field-id</span>s must be distinct. The order of the
<span class="RktVar">field-id</span>s need not match the order of the corresponding
fields in the structure type.</p><p>The <span class="RktVar">struct-expr</span> is evaluated first. The result must be an
instance of the <span class="RktVar">id</span> structure type, otherwise 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. Next, the field <span class="RktVar">expr</span>s are
evaluated in order (even if the fields that correspond to the
<span class="RktVar">field-id</span>s are in a different order). Finally, the new
structure instance is created.</p><p>The result of <span class="RktVar">struct-expr</span> can be an instance of a sub-type of
<span class="RktVar">id</span>, but the resulting copy is an immediate instance of
<span class="RktVar">id</span> (not the sub-type).</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">fish</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">color</span><span class="hspace"> </span><span class="RktSym">weight</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="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">marlin</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">fish</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">orange-and-white</span><span class="hspace"> </span><span class="RktVal">11</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><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.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">dory</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct-copy%29%29" class="RktStxLink" data-pltdoc="x">struct-copy</a></span><span class="hspace"> </span><span class="RktSym">fish</span><span class="hspace"> </span><span class="RktSym">marlin</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">color</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">blue</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="RktSym">dory</span></td></tr><tr><td><p><span class="RktRes">(fish 'blue 11)</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">shark</span><span class="hspace"> </span><span class="RktSym">fish</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">weeks-since-eating-fish</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="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">bruce</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">shark</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">grey</span><span class="hspace"> </span><span class="RktVal">110</span><span class="hspace"> </span><span class="RktVal">3</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><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.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">chum</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct-copy%29%29" class="RktStxLink" data-pltdoc="x">struct-copy</a></span><span class="hspace"> </span><span class="RktSym">shark</span><span class="hspace"> </span><span class="RktSym">bruce</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">weight</span><span class="hspace"> </span><span class="RktPn">#:parent</span><span class="hspace"> </span><span class="RktSym">fish</span><span class="hspace"> </span><span class="RktVal">90</span><span class="RktPn">]</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">weeks-since-eating-fish</span><span class="hspace"> </span><span class="RktVal">0</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="RktSym">chum</span></td></tr><tr><td><p><span class="RktRes">(shark 'grey 90 0)</span></p></td></tr><tr><td><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">subtypes can be copied as if they were supertypes,</span></td></tr><tr><td><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">but the result is an instance of the supertype</span></td></tr><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.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">not-really-chum</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct-copy%29%29" class="RktStxLink" data-pltdoc="x">struct-copy</a></span><span class="hspace"> </span><span class="RktSym">fish</span><span class="hspace"> </span><span class="RktSym">bruce</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">weight</span><span class="hspace"> </span><span class="RktVal">90</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="RktSym">not-really-chum</span></td></tr><tr><td><p><span class="RktRes">(fish 'grey 90)</span></p></td></tr></table></blockquote></div></p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.7", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.7");">top</a></span><span class="navright"> <a href="struct-generics.html" title="backward to "5.4 Generic Interfaces"" data-pltdoc="x">← prev</a> <a href="structures.html" title="up to "5 Structures"" data-pltdoc="x">up</a> <a href="structutils.html" title="forward to "5.6 Structure Utilities"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
|