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3.4 KiB
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61 lines
3.4 KiB
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<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
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<!Converted with LaTeX2HTML 0.6.5 (Tue Nov 15 1994) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<HEAD>
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<TITLE>23.1.5. Logical Pathnames</TITLE>
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<meta name="description" value=" Logical Pathnames">
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<meta name="resource-type" value="document">
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<meta name="distribution" value="global">
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<P>
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<b>Common Lisp the Language, 2nd Edition</b>
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<BR> <HR><A NAME=tex2html4155 HREF="node209.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html4153 HREF="node203.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html4147 HREF="node207.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html4157 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html4158 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html4156 HREF="node209.html"> Syntax of Logical </A>
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<B>Up:</B> <A NAME=tex2html4154 HREF="node203.html"> File Names</A>
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<B> Previous:</B> <A NAME=tex2html4148 HREF="node207.html"> Extended Wildcards</A>
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<HR> <P>
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<H2><A NAME=SECTION002715000000000000000>23.1.5. Logical Pathnames</A></H2>
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<P>
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<img align=bottom alt="change_begin" src="gif/change_begin.gif"><br>
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<A NAME=LOGICALPATHNAMESSECTION>Pathname</A>
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values are not portable, but sometimes they must be mentioned in a
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program (for example, the names of files containing the program and the
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data used by the program).
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<P>
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X3J13 voted in June 1989 (PATHNAME-LOGICAL) <A NAME=26479> </A> to provide
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some facilities for portable pathname values. The idea is to provide
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a portable framework for pathname values; these logical pathnames
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are then mapped to physical (that is, actual) pathnames by a set of implementation-dependent
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or site-dependent rules. The logical pathname facility therefore
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separates the concerns of program writing and user software architecture
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from the details of how a software system is embedded in a particular
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file system or operating environment.
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<P>
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Pathname values are not portable because not all Common Lisp
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implementations use the same operating system and file name syntax varies
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widely among operating systems. In addition, corresponding files at two
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different sites may have different names even when the operating system
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is the same; for example, they may be on different directories or
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different devices. The Common Lisp logical pathname system defines
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a particular pathname structure and namestring syntax that must be supported
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by all implementations.
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<P>
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<BR><b>[Class]</b><BR>
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<tt>logical-pathname</tt><P>This is a subclass of <tt>pathname</tt>.
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<br><img align=bottom alt="change_end" src="gif/change_end.gif">
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<P>
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<HR>
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<UL>
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<LI> <A NAME=tex2html4159 HREF="node209.html#SECTION002715100000000000000"> Syntax of Logical Pathname Namestrings</A>
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<LI> <A NAME=tex2html4160 HREF="node210.html#SECTION002715200000000000000"> Parsing of Logical Pathname Namestrings</A>
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<LI> <A NAME=tex2html4161 HREF="node211.html#SECTION002715300000000000000"> Using Logical Pathnames</A>
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<LI> <A NAME=tex2html4162 HREF="node212.html#SECTION002715400000000000000"> Examples of the Use of Logical Pathnames</A>
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<LI> <A NAME=tex2html4163 HREF="node213.html#SECTION002715500000000000000"> Discussion of Logical Pathnames</A>
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</UL>
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<HR>
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<P><ADDRESS>
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AI.Repository@cs.cmu.edu
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</ADDRESS>
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</BODY>
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