<?xml version="1.0"?><!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" lang="en"><head><title>Twisted Documentation: DirDBM: Directory-based Storage</title><link href="../howto/stylesheet.css" type="text/css" rel="stylesheet" /></head><body bgcolor="white"><h1 class="title">DirDBM: Directory-based Storage</h1><div class="toc"><ol><li><a href="#auto0">dirdbm.DirDBM</a></li><li><a href="#auto1">dirdbm.Shelf</a></li></ol></div><div class="content"><span></span><h2>dirdbm.DirDBM<a name="auto0"></a></h2><p><code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.persisted.dirdbm.DirDBM.html" title="twisted.persisted.dirdbm.DirDBM">twisted.persisted.dirdbm.DirDBM</a></code> is a DBM-like storage system. That is, it stores mappings between keys and values, like a Python dictionary, except that it stores the values in files in a directory - each entry is a different file. The keys must always be strings, as are the values. Other than that, <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.persisted.dirdbm.DirDBM.html" title="twisted.persisted.dirdbm.DirDBM">DirDBM</a></code> objects act just like Python dictionaries.</p><p><code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.persisted.dirdbm.DirDBM.html" title="twisted.persisted.dirdbm.DirDBM">DirDBM</a></code> is useful for cases when you want to store small amounts of data in an organized fashion, without having to deal with the complexity of a RDBMS or other sophisticated database. It is simple, easy to use, cross-platform, and doesn't require any external C libraries, unlike Python's built-in DBM modules.</p><pre class="python-interpreter"> >>> from twisted.persisted import dirdbm >>> d = dirdbm.DirDBM("/tmp/dir") >>> d["librarian"] = "ook" >>> d["librarian"] 'ook' >>> d.keys() ['librarian'] >>> del d["librarian"] >>> d.items() [] </pre><h2>dirdbm.Shelf<a name="auto1"></a></h2><p>Sometimes it is neccessary to persist more complicated objects than strings. With some care, <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.persisted.dirdbm.Shelf.html" title="twisted.persisted.dirdbm.Shelf">dirdbm.Shelf</a></code> can transparently persist them. <code>Shelf</code> works exactly like <code>DirDBM</code>, except that the values (but not the keys) can be arbitrary picklable objects. However, notice that mutating an object after it has been stored in the <code>Shelf</code> has no effect on the Shelf. When mutating objects, it is neccessary to explictly store them back in the <code>Shelf</code> afterwards:</p><pre class="python-interpreter"> >>> from twisted.persisted import dirdbm >>> d = dirdbm.Shelf("/tmp/dir2") >>> d["key"] = [1, 2] >>> d["key"] [1, 2] >>> l = d["key"] >>> l.append(3) >>> d["key"] [1, 2] >>> d["key"] = l >>> d["key"] [1, 2, 3] </pre></div><p><a href="../howto/index.html">Index</a></p><span class="version">Version: 1.3.0</span></body></html>