D7net
Home
Console
Upload
information
Create File
Create Folder
About
Tools
:
/
usr
/
share
/
doc
/
python3-docs
/
html
/
library
/
Filename :
linecache.html
back
Copy
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="X-UA-Compatible" content="IE=Edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>11.9. linecache — Random access to text lines — Python 3.6.7 documentation</title> <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 3.6.7 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="11.10. shutil — High-level file operations" href="shutil.html" /> <link rel="prev" title="11.8. fnmatch — Unix filename pattern matching" href="fnmatch.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/3/library/linecache.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> </head><body> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="shutil.html" title="11.10. shutil — High-level file operations" accesskey="N">next</a> |</li> <li class="right" > <a href="fnmatch.html" title="11.8. fnmatch — Unix filename pattern matching" accesskey="P">previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <a href="../index.html">3.6.7 Documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> <li class="nav-item nav-item-2"><a href="filesys.html" accesskey="U">11. File and Directory Access</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="module-linecache"> <span id="linecache-random-access-to-text-lines"></span><h1>11.9. <a class="reference internal" href="#module-linecache" title="linecache: This module provides random access to individual lines from text files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">linecache</span></code></a> — Random access to text lines<a class="headerlink" href="#module-linecache" title="Permalink to this headline">¶</a></h1> <p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.6/Lib/linecache.py">Lib/linecache.py</a></p> <hr class="docutils" /> <p>The <a class="reference internal" href="#module-linecache" title="linecache: This module provides random access to individual lines from text files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">linecache</span></code></a> module allows one to get any line from a Python source 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 <a class="reference internal" href="traceback.html#module-traceback" title="traceback: Print or retrieve a stack traceback."><code class="xref py py-mod docutils literal notranslate"><span class="pre">traceback</span></code></a> module to retrieve source lines for inclusion in the formatted traceback.</p> <p>The <a class="reference internal" href="tokenize.html#tokenize.open" title="tokenize.open"><code class="xref py py-func docutils literal notranslate"><span class="pre">tokenize.open()</span></code></a> function is used to open files. This function uses <a class="reference internal" href="tokenize.html#tokenize.detect_encoding" title="tokenize.detect_encoding"><code class="xref py py-func docutils literal notranslate"><span class="pre">tokenize.detect_encoding()</span></code></a> to get the encoding of the file; in the absence of an encoding token, the file encoding defaults to UTF-8.</p> <p>The <a class="reference internal" href="#module-linecache" title="linecache: This module provides random access to individual lines from text files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">linecache</span></code></a> module defines the following functions:</p> <dl class="function"> <dt id="linecache.getline"> <code class="descclassname">linecache.</code><code class="descname">getline</code><span class="sig-paren">(</span><em>filename</em>, <em>lineno</em>, <em>module_globals=None</em><span class="sig-paren">)</span><a class="headerlink" href="#linecache.getline" title="Permalink to this definition">¶</a></dt> <dd><p>Get line <em>lineno</em> from file named <em>filename</em>. This function will never raise an exception — it will return <code class="docutils literal notranslate"><span class="pre">''</span></code> on errors (the terminating newline character will be included for lines that are found).</p> <p id="index-0">If a file named <em>filename</em> is not found, the function will look for it in the module search path, <code class="docutils literal notranslate"><span class="pre">sys.path</span></code>, after first checking for a <span class="target" id="index-1"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> <code class="docutils literal notranslate"><span class="pre">__loader__</span></code> in <em>module_globals</em>, in case the module was imported from a zipfile or other non-filesystem import source.</p> </dd></dl> <dl class="function"> <dt id="linecache.clearcache"> <code class="descclassname">linecache.</code><code class="descname">clearcache</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#linecache.clearcache" title="Permalink to this definition">¶</a></dt> <dd><p>Clear the cache. Use this function if you no longer need lines from files previously read using <a class="reference internal" href="#linecache.getline" title="linecache.getline"><code class="xref py py-func docutils literal notranslate"><span class="pre">getline()</span></code></a>.</p> </dd></dl> <dl class="function"> <dt id="linecache.checkcache"> <code class="descclassname">linecache.</code><code class="descname">checkcache</code><span class="sig-paren">(</span><em>filename=None</em><span class="sig-paren">)</span><a class="headerlink" href="#linecache.checkcache" title="Permalink to this definition">¶</a></dt> <dd><p>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 <em>filename</em> is omitted, it will check all the entries in the cache.</p> </dd></dl> <dl class="function"> <dt id="linecache.lazycache"> <code class="descclassname">linecache.</code><code class="descname">lazycache</code><span class="sig-paren">(</span><em>filename</em>, <em>module_globals</em><span class="sig-paren">)</span><a class="headerlink" href="#linecache.lazycache" title="Permalink to this definition">¶</a></dt> <dd><p>Capture enough detail about a non-file-based module to permit getting its lines later via <a class="reference internal" href="#linecache.getline" title="linecache.getline"><code class="xref py py-func docutils literal notranslate"><span class="pre">getline()</span></code></a> even if <em>module_globals</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code> in the later call. This avoids doing I/O until a line is actually needed, without having to carry the module globals around indefinitely.</p> <div class="versionadded"> <p><span class="versionmodified">New in version 3.5.</span></p> </div> </dd></dl> <p>Example:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">linecache</span> <span class="gp">>>> </span><span class="n">linecache</span><span class="o">.</span><span class="n">getline</span><span class="p">(</span><span class="n">linecache</span><span class="o">.</span><span class="vm">__file__</span><span class="p">,</span> <span class="mi">8</span><span class="p">)</span> <span class="go">'import sys\n'</span> </pre></div> </div> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h4>Previous topic</h4> <p class="topless"><a href="fnmatch.html" title="previous chapter">11.8. <code class="docutils literal notranslate"><span class="pre">fnmatch</span></code> — Unix filename pattern matching</a></p> <h4>Next topic</h4> <p class="topless"><a href="shutil.html" title="next chapter">11.10. <code class="docutils literal notranslate"><span class="pre">shutil</span></code> — High-level file operations</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li> <a href="https://github.com/python/cpython/blob/3.6/Doc/library/linecache.rst" rel="nofollow">Show Source </a> </li> </ul> </div> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="shutil.html" title="11.10. shutil — High-level file operations" >next</a> |</li> <li class="right" > <a href="fnmatch.html" title="11.8. fnmatch — Unix filename pattern matching" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <a href="../index.html">3.6.7 Documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> <li class="nav-item nav-item-2"><a href="filesys.html" >11. File and Directory Access</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="footer"> © <a href="../copyright.html">Copyright</a> 2001-2021, Python Software Foundation. <br /> The Python Software Foundation is a non-profit corporation. <a href="https://www.python.org/psf/donations/">Please donate.</a> <br /> Last updated on Aug 25, 2021. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.7.6. </div> </body> </html>