41 lines
5.2 KiB
HTML
41 lines
5.2 KiB
HTML
<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
|
|
<HTML>
|
|
<HEAD>
|
|
<TITLE>CLHS: Section 20.1.2</TITLE>
|
|
<LINK HREF="../Data/clhs.css" REL="stylesheet" TYPE="text/css" />
|
|
<META HTTP-EQUIV="Author" CONTENT="Kent M. Pitman">
|
|
<META HTTP-EQUIV="Organization" CONTENT="LispWorks Ltd.">
|
|
<LINK REL=TOP HREF="../Front/index.htm">
|
|
<LINK REL=COPYRIGHT HREF="../Front/Help.htm#Legal">
|
|
<LINK REL=DISCLAIMER HREF="../Front/Help.htm#Disclaimer">
|
|
<LINK REL=PREV HREF="20_aa.htm">
|
|
<LINK REL=UP HREF="20_a.htm">
|
|
<LINK REL=NEXT HREF="20_ac.htm">
|
|
</HEAD>
|
|
<BODY>
|
|
<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="20_aa.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="20_a.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="20_ac.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
|
|
|
|
<HR>
|
|
|
|
<H2>
|
|
20.1.2 File Operations on Open and Closed Streams</H2> <P>
|
|
<P>
|
|
Many <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>functions</I></A> that perform <A REL=DEFINITION HREF="26_glo_f.htm#file"><I>file</I></A> operations accept either <A REL=DEFINITION HREF="26_glo_o.htm#open"><I>open</I></A> or <A REL=DEFINITION HREF="26_glo_c.htm#closed"><I>closed</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>streams</I></A> as <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A>; see <A REL=CHILD HREF="21_ac.htm">Section 21.1.3 (Stream Arguments to Standardized Functions)</A>. <P>
|
|
Of these, the <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>functions</I></A> in the next figure treat <A REL=DEFINITION HREF="26_glo_o.htm#open"><I>open</I></A> and <A REL=DEFINITION HREF="26_glo_c.htm#closed"><I>closed</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>streams</I></A> differently. <P>
|
|
<PRE>
|
|
<A REL=DEFINITION HREF="f_del_fi.htm#delete-file">delete-file</A> <A REL=DEFINITION HREF="f_file_a.htm#file-author">file-author</A> <A REL=DEFINITION HREF="f_probe_.htm#probe-file">probe-file</A>
|
|
<A REL=DEFINITION HREF="f_dir.htm#directory">directory</A> <A REL=DEFINITION HREF="f_file_w.htm#file-write-date">file-write-date</A> <A REL=DEFINITION HREF="f_tn.htm#truename">truename</A>
|
|
</PRE>
|
|
<P><B>Figure 20-2. File Functions that Treat Open and Closed Streams Differently</B> <P>
|
|
Since treatment of <A REL=DEFINITION HREF="26_glo_o.htm#open"><I>open</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>streams</I></A> by the <A REL=DEFINITION HREF="26_glo_f.htm#file_system"><I>file system</I></A> may vary considerably between <A REL=DEFINITION HREF="26_glo_i.htm#implementation"><I>implementations</I></A>, however, a <A REL=DEFINITION HREF="26_glo_c.htm#closed"><I>closed</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>stream</I></A> might be the most reliable kind of <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>argument</I></A> for some of these functions---in particular, those in the next figure. For example, in some <A REL=DEFINITION HREF="26_glo_f.htm#file_system"><I>file systems</I></A>, <A REL=DEFINITION HREF="26_glo_o.htm#open"><I>open</I></A> <A REL=DEFINITION HREF="26_glo_f.htm#file"><I>files</I></A> are written under temporary names and not renamed until <A REL=DEFINITION HREF="26_glo_c.htm#closed"><I>closed</I></A> and/or are held invisible until <A REL=DEFINITION HREF="26_glo_c.htm#closed"><I>closed</I></A>. In general, any code that is intended to be portable should use such <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>functions</I></A> carefully. <P>
|
|
<PRE>
|
|
<A REL=DEFINITION HREF="f_dir.htm#directory">directory</A> <A REL=DEFINITION HREF="f_probe_.htm#probe-file">probe-file</A> <A REL=DEFINITION HREF="f_tn.htm#truename">truename</A>
|
|
</PRE>
|
|
<P><B>Figure 20-3. File Functions where Closed Streams Might Work Best</B> <P>
|
|
<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issue</A>, <I>not part of the specification</I>, applies to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss053.htm">CLOSED-STREAM-OPERATIONS:ALLOW-INQUIRY</A><P></UL><HR>
|
|
|
|
<A REL=NAVIGATOR HREF="../Front/StartPts.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Starting Points]" SRC="../Graphics/StartPts.gif" ALIGN=Bottom></A><A REL=TOC HREF="../Front/Contents.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Contents]" SRC="../Graphics/Contents.gif" ALIGN=Bottom></A><A REL=INDEX HREF="../Front/X_Master.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Index]" SRC="../Graphics/Index.gif" ALIGN=Bottom></A><A REL=INDEX HREF="../Front/X_Symbol.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Symbols]" SRC="../Graphics/Symbols.gif" ALIGN=Bottom></A><A REL=GLOSSARY HREF="../Body/26_a.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Glossary]" SRC="../Graphics/Glossary.gif" ALIGN=Bottom></A><A HREF="../Front/X3J13Iss.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Issues]" SRC="../Graphics/Issues.gif" ALIGN=Bottom></A><BR>
|
|
|
|
<A REL=COPYRIGHT HREF="../Front/Help.htm#Legal"><I>Copyright 1996-2005, LispWorks Ltd. All rights reserved.</I></A><P>
|
|
</BODY>
|
|
</HTML>
|