cpython/Doc/lib/liblinecache.tex

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\section{\module{linecache} ---
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Random access to text lines}
\declaremodule{standard}{linecache}
\sectionauthor{Moshe Zadka}{mzadka@geocities.com}
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\modulesynopsis{This module provides random access to individual lines
from text files.}
The \module{linecache} module allows one to get any line from any file,
while attempting to optimize internally, using a cache, the common case
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where many lines are read from a single file. This is used by the
\refmodule{traceback} module to retrieve source lines for inclusion in
the formatted traceback.
The \module{linecache} module defines the following functions:
\begin{funcdesc}{getline}{filename, lineno}
Get line \var{lineno} from file named \var{filename}. This function
will never throw an exception --- it will return \code{''} on errors
(the terminating newline character will be included for lines that are
found).
If a file named \var{filename} is not found, the function will look
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for it in the module\indexiii{module}{search}{path} search path,
\code{sys.path}.
\end{funcdesc}
\begin{funcdesc}{clearcache}{}
Clear the cache. Use this function if you no longer need lines from
files previously read using \function{getline()}.
\end{funcdesc}
\begin{funcdesc}{checkcache}{}
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Check the cache for validity. Use this function if files in the cache
may have changed on disk, and you require the updated version.
\end{funcdesc}
Example:
\begin{verbatim}
>>> import linecache
>>> linecache.getline('/etc/passwd', 4)
'sys:x:3:3:sys:/dev:/bin/sh\012'
\end{verbatim}