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<title>3.13 linecache -- Random access to text lines
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<H1><A NAME=
"SECTION0051300000000000000000">
3.13 <tt class=
"module">linecache
</tt> --
Random access to text lines
</A>
<A NAME=
"module-linecache"></A>
The
<tt class=
"module">linecache
</tt> module allows one to get any line from any file,
while attempting to optimize internally, using a cache, the common case
where many lines are read from a single file. This is used by the
<tt class=
"module"><a href=
"module-traceback.html">traceback
</a></tt> module to retrieve source lines for inclusion in
The
<tt class=
"module">linecache
</tt> module defines the following functions:
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
621' xml:id='l2h-
621'
class=
"function">getline
</tt></b>(
</nobr></td>
<td><var>filename, lineno
</var>)
</td></tr></table></dt>
Get line
<var>lineno
</var> from file named
<var>filename
</var>. This function
will never throw an exception -- it will return
<code>''
</code> on errors
(the terminating newline character will be included for lines that are
If a file named
<var>filename
</var> is not found, the function will look
for it in the module
<a id='l2h-
622' xml:id='l2h-
622'
></a> search path,
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
623' xml:id='l2h-
623'
class=
"function">clearcache
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Clear the cache. Use this function if you no longer need lines from
files previously read using
<tt class=
"function">getline()
</tt>.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
624' xml:id='l2h-
624'
class=
"function">checkcache
</tt></b>(
</nobr></td>
<td><var></var><big>[
</big><var>filename
</var><big>]
</big><var></var>)
</td></tr></table></dt>
Check the cache for validity. Use this function if files in the cache
may have changed on disk, and you require the updated version. If
<var>filename
</var> is omitted, it will check the whole cache entries.
<div class=
"verbatim"><pre>
>>> import linecache
>>> linecache.getline('/etc/passwd',
4)
'sys:x:
3:
3:sys:/dev:/bin/sh\n'
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<span class=
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2.4.2, documentation updated on
28 September
2005.
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