34 lines
No EOL
41 KiB
HTML
34 lines
No EOL
41 KiB
HTML
<!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"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>13.1.2 Managing Ports</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="tocviewselflink" 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>13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr></table><div class="tocviewsublist" style="display: none;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">13.1 </td><td><a href="ports.html" class="tocviewselflink" data-pltdoc="x">Ports</a></td></tr><tr><td align="right">13.2 </td><td><a href="Byte_and_String_Input.html" class="tocviewlink" data-pltdoc="x">Byte and String Input</a></td></tr><tr><td align="right">13.3 </td><td><a href="Byte_and_String_Output.html" class="tocviewlink" data-pltdoc="x">Byte and String Output</a></td></tr><tr><td align="right">13.4 </td><td><a href="Reading.html" class="tocviewlink" data-pltdoc="x">Reading</a></td></tr><tr><td align="right">13.5 </td><td><a href="Writing.html" class="tocviewlink" data-pltdoc="x">Writing</a></td></tr><tr><td align="right">13.6 </td><td><a href="pretty-print.html" class="tocviewlink" data-pltdoc="x">Pretty Printing</a></td></tr><tr><td align="right">13.7 </td><td><a href="Reader_Extension.html" class="tocviewlink" data-pltdoc="x">Reader Extension</a></td></tr><tr><td align="right">13.8 </td><td><a href="Printer_Extension.html" class="tocviewlink" data-pltdoc="x">Printer Extension</a></td></tr><tr><td align="right">13.9 </td><td><a href="serialization.html" class="tocviewlink" data-pltdoc="x">Serialization</a></td></tr><tr><td align="right">13.10 </td><td><a href="fasl.html" class="tocviewlink" data-pltdoc="x">Fast-<wbr></wbr>Load Serialization</a></td></tr><tr><td align="right">13.11 </td><td><a href="sha.html" class="tocviewlink" data-pltdoc="x">Cryptographic Hashing</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_2");">▼</a></td><td>13.1 </td><td><a href="ports.html" class="tocviewlink" data-pltdoc="x">Ports</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_2"><table cellspacing="0" cellpadding="0"><tr><td align="right">13.1.1 </td><td><a href="encodings.html" class="tocviewlink" data-pltdoc="x">Encodings and Locales</a></td></tr><tr><td align="right">13.1.2 </td><td><a href="port-ops.html" class="tocviewselflink" data-pltdoc="x">Managing Ports</a></td></tr><tr><td align="right">13.1.3 </td><td><a href="port-buffers.html" class="tocviewlink" data-pltdoc="x">Port Buffers and Positions</a></td></tr><tr><td align="right">13.1.4 </td><td><a href="linecol.html" class="tocviewlink" data-pltdoc="x">Counting Positions, Lines, and Columns</a></td></tr><tr><td align="right">13.1.5 </td><td><a href="file-ports.html" class="tocviewlink" data-pltdoc="x">File Ports</a></td></tr><tr><td align="right">13.1.6 </td><td><a href="stringport.html" class="tocviewlink" data-pltdoc="x">String Ports</a></td></tr><tr><td align="right">13.1.7 </td><td><a href="pipeports.html" class="tocviewlink" data-pltdoc="x">Pipes</a></td></tr><tr><td align="right">13.1.8 </td><td><a href="portstructs.html" class="tocviewlink" data-pltdoc="x">Structures as Ports</a></td></tr><tr><td align="right">13.1.9 </td><td><a href="customport.html" class="tocviewlink" data-pltdoc="x">Custom Ports</a></td></tr><tr><td align="right">13.1.10 </td><td><a href="port-lib.html" class="tocviewlink" data-pltdoc="x">More Port Constructors, Procedures, and Events</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="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">input-<wbr></wbr>port?</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._output-port~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">output-<wbr></wbr>port?</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._port~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">port?</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-input-port%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">close-<wbr></wbr>input-<wbr></wbr>port</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-output-port%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">close-<wbr></wbr>output-<wbr></wbr>port</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._port-closed~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">port-<wbr></wbr>closed?</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._port-closed-evt%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">port-<wbr></wbr>closed-<wbr></wbr>evt</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-input-port%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">current-<wbr></wbr>input-<wbr></wbr>port</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-output-port%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">current-<wbr></wbr>output-<wbr></wbr>port</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-error-port%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">current-<wbr></wbr>error-<wbr></wbr>port</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._file-stream-port~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">file-<wbr></wbr>stream-<wbr></wbr>port?</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._terminal-port~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">terminal-<wbr></wbr>port?</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._port-waiting-peer~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">port-<wbr></wbr>waiting-<wbr></wbr>peer?</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">eof</span></span></a></td></tr><tr><td><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof-object~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">eof-<wbr></wbr>object?</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" 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="encodings.html" title="backward to "13.1.1 Encodings and Locales"" data-pltdoc="x">← prev</a> <a href="ports.html" title="up to "13.1 Ports"" data-pltdoc="x">up</a> <a href="port-buffers.html" title="forward to "13.1.3 Port Buffers and Positions"" data-pltdoc="x">next →</a></span> </div><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""port-ops"">13.1.2<tt> </tt><a name="(part._port-ops)"></a>Managing Ports</h5><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)._input-port~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">input-port?</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 <span class="RktVar">v</span> is an <a href="ports.html#%28tech._input._port%29" class="techoutside" data-pltdoc="x"><span class="techinside">input port</span></a>, <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)._output-port~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._output-port~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">output-port?</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 <span class="RktVar">v</span> is an <a href="ports.html#%28tech._output._port%29" class="techoutside" data-pltdoc="x"><span class="techinside">output port</span></a>, <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._((lib._racket/private/misc..rkt)._port~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._port~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">port?</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 either <span class="RktPn">(</span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span><span class="stt"> </span><span class="RktVar">v</span><span class="RktPn">)</span> or
|
|
<span class="RktPn">(</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="stt"> </span><span class="RktVar">v</span><span class="RktPn">)</span> is <span class="RktVal">#t</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)._close-input-port))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-input-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">close-input-port</a></span></span><span class="hspace"> </span><span class="RktVar">in</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></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">in</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Closes the input port <span class="RktVar">in</span>. For some kinds of ports, closing
|
|
the port releases lower-level resources, such as a file handle. If
|
|
the port is already closed, <span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-input-port%29%29" class="RktValLink" data-pltdoc="x">close-input-port</a></span> has no effect.</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)._close-output-port))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-output-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">close-output-port</a></span></span><span class="hspace"> </span><span class="RktVar">out</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></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">out</span><span class="hspace"> </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></td></tr></table></blockquote></div><div class="SIntrapara">Closes the output port <span class="RktVar">out</span>. For some kinds of ports, closing
|
|
the port releases lower-level resources, such as a file handle. Also,
|
|
if the port is buffered, closing may first flush the port before
|
|
closing it, and this flushing process can block. If the port is
|
|
already closed, <span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-output-port%29%29" class="RktValLink" data-pltdoc="x">close-output-port</a></span> has no effect.</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)._port-closed~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._port-closed~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">port-closed?</a></span></span><span class="hspace"> </span><span class="RktVar">port</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">port</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._port~3f%29%29" class="RktValLink" data-pltdoc="x">port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if the input or output port <span class="RktVar">port</span> is
|
|
closed, <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)._port-closed-evt))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._port-closed-evt%29%29" class="RktValDef RktValLink" data-pltdoc="x">port-closed-evt</a></span></span><span class="hspace"> </span><span class="RktVar">port</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="sync.html#%28def._%28%28quote._~23~25kernel%29._evt~3f%29%29" class="RktValLink" data-pltdoc="x">evt?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">port</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._port~3f%29%29" class="RktValLink" data-pltdoc="x">port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Return a <a href="sync.html#%28tech._synchronizable._event%29" class="techoutside" data-pltdoc="x"><span class="techinside">synchronizable event</span></a> that becomes <a href="sync.html#%28tech._ready._for._synchronization%29" class="techoutside" data-pltdoc="x"><span class="techinside">ready for
|
|
synchronization</span></a> when <span class="RktVar">port</span> is
|
|
closed. The <a href="sync.html#%28tech._synchronization._result%29" class="techoutside" data-pltdoc="x"><span class="techinside">synchronization result</span></a> of a port-closed event is the port-closed event itself.</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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._current-input-port))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-input-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-input-port</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</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="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-input-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-input-port</a></span></span><span class="hspace"> </span><span class="RktVar">in</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">in</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</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 a default input port for many operations, such as
|
|
<span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span>.</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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._current-output-port))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-output-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-output-port</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </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></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-output-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-output-port</a></span></span><span class="hspace"> </span><span class="RktVar">out</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">out</span><span class="hspace"> </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></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 a default output port for many operations, such as
|
|
<span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._write%29%29" class="RktValLink" data-pltdoc="x">write</a></span>.</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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._current-error-port))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-error-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-error-port</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </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></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-error-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-error-port</a></span></span><span class="hspace"> </span><span class="RktVar">out</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">out</span><span class="hspace"> </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></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 output port that is typically used for errors and
|
|
logging. For example, the default error display handler writes to this
|
|
port.</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)._file-stream-port~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._file-stream-port~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">file-stream-port?</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 <span class="RktVar">v</span> is a <a href="file-ports.html#%28tech._file._stream._port%29" class="techoutside" data-pltdoc="x"><span class="techinside">file-stream port</span></a> (see
|
|
<a href="file-ports.html" data-pltdoc="x">File Ports</a>), <span class="RktVal">#f</span> otherwise.</div></p><p class="SHistory">Changed in version 7.2.0.5 of package <span class="stt">base</span>: Extended <span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._file-stream-port~3f%29%29" class="RktValLink" data-pltdoc="x">file-stream-port?</a></span>
|
|
to any value, instead of resticting
|
|
the domain to ports</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)._terminal-port~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._terminal-port~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">terminal-port?</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 <span class="RktVar">v</span> is a port that is attached to an
|
|
interactive terminal, <span class="RktVal">#f</span> otherwise.</div></p><p class="SHistory">Changed in version 7.2.0.5 of package <span class="stt">base</span>: Extended <span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._terminal-port~3f%29%29" class="RktValLink" data-pltdoc="x">terminal-port?</a></span>
|
|
to any value, instead of resticting
|
|
the domain to ports</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)._port-waiting-peer~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._port-waiting-peer~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">port-waiting-peer?</a></span></span><span class="hspace"> </span><span class="RktVar">port</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">port</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._port~3f%29%29" class="RktValLink" data-pltdoc="x">port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">port</span> is not ready for reading or
|
|
writing because it is waiting for a peer process to complete a stream
|
|
construction, <span class="RktVal">#f</span> otherwise.</div></p><p>On Unix and Mac OS, opening a fifo for output creates a peer-waiting
|
|
port if no reader for the same fifo is already opened. In that case,
|
|
the output port is not ready for writing until a reader is opened;
|
|
that is, write opertaions will block. Use <span class="RktSym"><a href="sync.html#%28def._%28%28quote._~23~25kernel%29._sync%29%29" class="RktValLink" data-pltdoc="x">sync</a></span> if necessary
|
|
to wait until writing will not block—<wbr></wbr>that is, until the read end of
|
|
the fifo is opened.</p><p class="SHistory">Added in version 7.4.0.5 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>value</p></div></div><p class="RForeground"><a name="(def._((quote._~23~25kernel)._eof))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof%29%29" class="RktValDef RktValLink" data-pltdoc="x">eof</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof-object~3f%29%29" class="RktValLink" data-pltdoc="x">eof-object?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A value (distinct from all other values)
|
|
that represents an end-of-file.</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)._eof-object~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof-object~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">eof-object?</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
|
|
<span class="RktVar">v</span> is <span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof%29%29" class="RktValLink" data-pltdoc="x">eof</a></span>, <span class="RktVal">#f</span> otherwise.</div></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="encodings.html" title="backward to "13.1.1 Encodings and Locales"" data-pltdoc="x">← prev</a> <a href="ports.html" title="up to "13.1 Ports"" data-pltdoc="x">up</a> <a href="port-buffers.html" title="forward to "13.1.3 Port Buffers and Positions"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html> |