Edit File: bastion.html
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Bastion — Restricting access to objects — Python v2.6.6 documentation</title> <link rel="stylesheet" href="../_static/default.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '2.6.6', COLLAPSE_MODINDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python v2.6.6 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="top" title="Python v2.6.6 documentation" href="../index.html" /> <link rel="up" title="29. 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Restricted Execution</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body"> <div class="section" id="module-Bastion"> <h1>29.2. <tt class="xref docutils literal"><span class="pre">Bastion</span></tt> — Restricting access to objects<a class="headerlink" href="#module-Bastion" title="Permalink to this headline">¶</a></h1> <p class="deprecated"> <span class="versionmodified">Deprecated since version 2.6: </span>The <tt class="xref docutils literal"><span class="pre">Bastion</span></tt> module has been removed in Python 3.0.</p> <p class="versionchanged"> <span class="versionmodified">Changed in version 2.3: </span>Disabled module.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">The documentation has been left in place to help in reading old code that uses the module.</p> </div> <p>According to the dictionary, a bastion is “a fortified area or position”, or “something that is considered a stronghold.” It’s a suitable name for this module, which provides a way to forbid access to certain attributes of an object. It must always be used with the <a title="Basic restricted execution framework. (deprecated)" class="reference external" href="rexec.html#module-rexec"><tt class="xref docutils literal"><span class="pre">rexec</span></tt></a> module, in order to allow restricted-mode programs access to certain safe attributes of an object, while denying access to other, unsafe attributes.</p> <dl class="function"> <dt id="Bastion.Bastion"> <tt class="descclassname">Bastion.</tt><tt class="descname">Bastion</tt><big>(</big><em>object</em><span class="optional">[</span>, <em>filter</em><span class="optional">[</span>, <em>name</em><span class="optional">[</span>, <em>class</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#Bastion.Bastion" title="Permalink to this definition">¶</a></dt> <dd><p>Protect the object <em>object</em>, returning a bastion for the object. Any attempt to access one of the object’s attributes will have to be approved by the <em>filter</em> function; if the access is denied an <a title="exceptions.AttributeError" class="reference external" href="exceptions.html#exceptions.AttributeError"><tt class="xref docutils literal"><span class="pre">AttributeError</span></tt></a> exception will be raised.</p> <p>If present, <em>filter</em> must be a function that accepts a string containing an attribute name, and returns true if access to that attribute will be permitted; if <em>filter</em> returns false, the access is denied. The default filter denies access to any function beginning with an underscore (<tt class="docutils literal"><span class="pre">'_'</span></tt>). The bastion’s string representation will be <tt class="docutils literal"><span class="pre"><Bastion</span> <span class="pre">for</span> <span class="pre">name></span></tt> if a value for <em>name</em> is provided; otherwise, <tt class="docutils literal"><span class="pre">repr(object)</span></tt> will be used.</p> <p><em>class</em>, if present, should be a subclass of <a title="Bastion.BastionClass" class="reference internal" href="#Bastion.BastionClass"><tt class="xref docutils literal"><span class="pre">BastionClass</span></tt></a>; see the code in <tt class="docutils literal"><span class="pre">bastion.py</span></tt> for the details. Overriding the default <a title="Bastion.BastionClass" class="reference internal" href="#Bastion.BastionClass"><tt class="xref docutils literal"><span class="pre">BastionClass</span></tt></a> will rarely be required.</p> </dd></dl> <dl class="class"> <dt id="Bastion.BastionClass"> <em class="property">class </em><tt class="descclassname">Bastion.</tt><tt class="descname">BastionClass</tt><big>(</big><em>getfunc</em>, <em>name</em><big>)</big><a class="headerlink" href="#Bastion.BastionClass" title="Permalink to this definition">¶</a></dt> <dd>Class which actually implements bastion objects. This is the default class used by <a title="Bastion.Bastion" class="reference internal" href="#Bastion.Bastion"><tt class="xref docutils literal"><span class="pre">Bastion()</span></tt></a>. The <em>getfunc</em> parameter is a function which returns the value of an attribute which should be exposed to the restricted execution environment when called with the name of the attribute as the only parameter. <em>name</em> is used to construct the <a title="repr" class="reference external" href="functions.html#repr"><tt class="xref docutils literal"><span class="pre">repr()</span></tt></a> of the <a title="Bastion.BastionClass" class="reference internal" href="#Bastion.BastionClass"><tt class="xref docutils literal"><span class="pre">BastionClass</span></tt></a> instance.</dd></dl> </div> </div> </div> </div> <div class="sphinxsidebar"> <div class="sphinxsidebarwrapper"> <h4>Previous topic</h4> <p class="topless"><a href="rexec.html" title="previous chapter">29.1. <tt class="docutils literal"><span class="pre">rexec</span></tt> — Restricted execution framework</a></p> <h4>Next topic</h4> <p class="topless"><a href="modules.html" title="next chapter">30. 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