Sophie: sbcl-1.0.31-1mdv2010.0 i586

sbcl-1.0.31-1mdv2010.0.i586.rpm

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<h3 class="section">9.2 Native Filenames</h3>

<p>In some circumstances, what is wanted is a Lisp pathname object which
corresponds to a string produced by the Operating System.  In this case,
some of the default parsing rules are inappropriate: most filesystems do
not have a native understanding of wild pathnames; such functionality is
often provided by shells above the OS, often in mutually-incompatible
ways.

   <p>To allow the user to deal with this, the following functions are
provided: <code>parse-native-namestring</code> and <code>native-pathname</code>
return the closest equivalent Lisp pathname to a given string
(appropriate for the Operating System), while <code>native-namestring</code>
converts a non-wild pathname designator to the equivalent native
namestring, if possible.  Some Lisp pathname concepts (such as the
<code>:back</code> directory component) have no direct equivalents in most
Operating Systems; the behaviour of <code>native-namestring</code> is
unspecified if an inappropriate pathname designator is passed to it. 
Additionally, note that conversion from pathname to native filename
and back to pathname should not be expected to preserve equivalence
under <code>equal</code>.

   <p><a name="Function-sb_002dext_003aparse_002dnative_002dnamestring"></a>

<div class="defun">
&mdash; Function: <b>sb-ext:parse-native-namestring</b><var> thing &amp;optional host defaults &amp;key start end junk-allowed as-directory<a name="index-sb_002dext_003aparse_002dnative_002dnamestring-309"></a></var><br>
<blockquote><p><a name="index-sb_002dext_003aparse_002dnative_002dnamestring-310"></a>Convert <code>thing</code> into a pathname, using the native conventions
appropriate for the pathname host <code>host</code>, or if not specified the
host of <code>defaults</code>.  If <code>thing</code> is a string, the parse is bounded by
<code>start</code> and <code>end</code>, and error behaviour is controlled by <code>junk-allowed</code>,
as with <code>parse-namestring</code>.  For file systems whose native
conventions allow directories to be indicated as files, if
<code>as-directory</code> is true, return a pathname denoting <code>thing</code> as a
directory. 
</p></blockquote></div>

   <p><a name="Function-sb_002dext_003anative_002dpathname"></a>

<div class="defun">
&mdash; Function: <b>sb-ext:native-pathname</b><var> pathspec<a name="index-sb_002dext_003anative_002dpathname-311"></a></var><br>
<blockquote><p><a name="index-sb_002dext_003anative_002dpathname-312"></a>Convert <code>pathspec</code> (a pathname designator) into a pathname, assuming
the operating system native pathname conventions. 
</p></blockquote></div>

   <p><a name="Function-sb_002dext_003anative_002dnamestring"></a>

<div class="defun">
&mdash; Function: <b>sb-ext:native-namestring</b><var> pathname &amp;key as-file<a name="index-sb_002dext_003anative_002dnamestring-313"></a></var><br>
<blockquote><p><a name="index-sb_002dext_003anative_002dnamestring-314"></a>Construct the full native (name)string form of <code>pathname</code>.  For
file systems whose native conventions allow directories to be
indicated as files, if <code>as-file</code> is true and the name, type, and
version components of <code>pathname</code> are all <code>nil</code> or <code>:unspecific</code>,
construct a string that names the directory according to the file
system's syntax for files. 
</p></blockquote></div>

   <p>Because some file systems permit the names of directories to be
expressed in multiple ways, it is occasionally necessary to parse a
native file name &ldquo;as a directory name&rdquo; or to produce a native file
name that names a directory &ldquo;as a file&rdquo;.  For these cases,
<code>parse-native-namestring</code> accepts the keyword argument
<code>as-directory</code> to force a filename to parse as a directory, and
<code>native-namestring</code> accepts the keyword argument <code>as-file</code>
to force a pathname to unparse as a file.  For example,

<pre class="lisp">     ; On Unix, the directory "/tmp/" can be denoted by "/tmp/" or "/tmp".
     ; Under the default rules for native filenames, these parse and
     ; unparse differently.
     (defvar *p*)
     (setf *p* (parse-native-namestring "/tmp/")) &rArr; #P"/tmp/"
     (pathname-name *p*) &rArr; NIL
     (pathname-directory *p*) &rArr; (:ABSOLUTE "tmp")
     (native-namestring *p*) &rArr; "/tmp/"
     
     (setf *p* (parse-native-namestring "/tmp")) &rArr; #P"/tmp"
     (pathname-name *p*) &rArr; "tmp"
     (pathname-directory *p*) &rArr; (:ABSOLUTE)
     (native-namestring *p*) &rArr; "/tmp"
     
     ; A non-NIL AS-DIRECTORY argument to PARSE-NATIVE-NAMESTRING forces
     ; both the second string to parse the way the first does.
     (setf *p* (parse-native-namestring "/tmp"
                                        nil *default-pathname-defaults*
                                        :as-directory t)) &rArr; #P"/tmp/"
     (pathname-name *p*) &rArr; NIL
     (pathname-directory *p*) &rArr; (:ABSOLUTE "tmp")
     
     ; A non-NIL AS-FILE argument to NATIVE-NAMESTRING forces the pathname
     ; parsed from the first string to unparse as the second string.
     (setf *p* (parse-native-namestring "/tmp/")) &rArr; #P"/tmp/"
     (native-namestring *p* :as-file t) &rArr; "/tmp"
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