📄 module-bastion.html
字号:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>16.2 Bastion -- Restricting access to objects</title>
<META NAME="description" CONTENT="16.2 Bastion -- Restricting access to objects">
<META NAME="keywords" CONTENT="lib">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<link rel="STYLESHEET" href="lib.css" tppabs="http://www.python.org/doc/current/lib/lib.css">
<LINK REL="previous" href="module-rexec.html" tppabs="http://www.python.org/doc/current/lib/module-rexec.html">
<LINK REL="up" href="restricted.html" tppabs="http://www.python.org/doc/current/lib/restricted.html">
<LINK REL="next" href="language.html" tppabs="http://www.python.org/doc/current/lib/language.html">
</head>
<body>
<DIV CLASS="navigation"><table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td><A HREF="node366.html" tppabs="http://www.python.org/doc/current/lib/node366.html"><img src="previous.gif" tppabs="http://www.python.org/doc/current/icons/previous.gif" border="0" height="32"
alt="Previous Page" width="32"></A></td>
<td><A href="restricted.html" tppabs="http://www.python.org/doc/current/lib/restricted.html"><img src="up.gif" tppabs="http://www.python.org/doc/current/icons/up.gif" border="0" height="32"
alt="Up One Level" width="32"></A></td>
<td><A href="language.html" tppabs="http://www.python.org/doc/current/lib/language.html"><img src="next.gif" tppabs="http://www.python.org/doc/current/icons/next.gif" border="0" height="32"
alt="Next Page" width="32"></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td><A href="contents.html" tppabs="http://www.python.org/doc/current/lib/contents.html"><img src="contents.gif" tppabs="http://www.python.org/doc/current/icons/contents.gif" border="0" height="32"
alt="Contents" width="32"></A></td>
<td><a href="modindex.html" tppabs="http://www.python.org/doc/current/lib/modindex.html" title="Module Index"><img src="modules.gif" tppabs="http://www.python.org/doc/current/icons/modules.gif" border="0" height="32"
alt="Module Index" width="32"></a></td>
<td><A href="genindex.html" tppabs="http://www.python.org/doc/current/lib/genindex.html"><img src="index.gif" tppabs="http://www.python.org/doc/current/icons/index.gif" border="0" height="32"
alt="Index" width="32"></A></td>
</tr></table>
<b class="navlabel">Previous:</b> <a class="sectref" HREF="node366.html" tppabs="http://www.python.org/doc/current/lib/node366.html">16.1.1 An example</A>
<b class="navlabel">Up:</b> <a class="sectref" href="restricted.html" tppabs="http://www.python.org/doc/current/lib/restricted.html">16. Restricted Execution</A>
<b class="navlabel">Next:</b> <a class="sectref" href="language.html" tppabs="http://www.python.org/doc/current/lib/language.html">17. Python Language Services</A>
<br><hr></DIV>
<!--End of Navigation Panel-->
<H1><A NAME="SECTION0018200000000000000000">
16.2 <tt class="module">Bastion</tt> --
Restricting access to objects</A>
</H1>
<P>
<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
<tt class='module'><a href="module-rexec.html" tppabs="http://www.python.org/doc/current/lib/module-rexec.html">rexec</a></tt> 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><dt><b><a name='l2h-3008'><tt class='function'>Bastion</tt></a></b> (<var>object</var><big>[</big><var>, filter</var><big>[</big><var>,
name</var><big>[</big><var>, class</var><big>]</big><big>]</big><big>]</big>)
<dd>
Protect the object <var>object</var>, returning a bastion for the
object. Any attempt to access one of the object's attributes will
have to be approved by the <var>filter</var> function; if the access is
denied an <tt class="exception">AttributeError</tt> exception will be raised.
<P>
If present, <var>filter</var> must be a function that accepts a string
containing an attribute name, and returns true if access to that
attribute will be permitted; if <var>filter</var> returns false, the access
is denied. The default filter denies access to any function beginning
with an underscore ("<tt class="character">_</tt>"). The bastion's string representation
will be "<tt class="samp"><Bastion for <var>name</var>></tt>" if a value for
<var>name</var> is provided; otherwise, "<tt class="samp">repr(<var>object</var>)</tt>" will be
used.
<P>
<var>class</var>, if present, should be a subclass of <tt class="class">BastionClass</tt>;
see the code in <span class="file">bastion.py</span> for the details. Overriding the
default <tt class="class">BastionClass</tt> will rarely be required.
</dl>
<P>
<dl><dt><b><a name='l2h-3009'><tt class='class'>BastionClass</tt></a></b> (<var>getfunc, name</var>)
<dd>
Class which actually implements bastion objects. This is the default
class used by <tt class="function">Bastion()</tt>. The <var>getfunc</var> 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. <var>name</var> is used to
construct the <tt class="function">repr()</tt> of the <tt class="class">BastionClass</tt> instance.
</dl>
<P>
<DIV CLASS="navigation"><p><hr><table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td><A HREF="node366.html" tppabs="http://www.python.org/doc/current/lib/node366.html"><img src="previous.gif" tppabs="http://www.python.org/doc/current/icons/previous.gif" border="0" height="32"
alt="Previous Page" width="32"></A></td>
<td><A href="restricted.html" tppabs="http://www.python.org/doc/current/lib/restricted.html"><img src="up.gif" tppabs="http://www.python.org/doc/current/icons/up.gif" border="0" height="32"
alt="Up One Level" width="32"></A></td>
<td><A href="language.html" tppabs="http://www.python.org/doc/current/lib/language.html"><img src="next.gif" tppabs="http://www.python.org/doc/current/icons/next.gif" border="0" height="32"
alt="Next Page" width="32"></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td><A href="contents.html" tppabs="http://www.python.org/doc/current/lib/contents.html"><img src="contents.gif" tppabs="http://www.python.org/doc/current/icons/contents.gif" border="0" height="32"
alt="Contents" width="32"></A></td>
<td><a href="modindex.html" tppabs="http://www.python.org/doc/current/lib/modindex.html" title="Module Index"><img src="modules.gif" tppabs="http://www.python.org/doc/current/icons/modules.gif" border="0" height="32"
alt="Module Index" width="32"></a></td>
<td><A href="genindex.html" tppabs="http://www.python.org/doc/current/lib/genindex.html"><img src="index.gif" tppabs="http://www.python.org/doc/current/icons/index.gif" border="0" height="32"
alt="Index" width="32"></A></td>
</tr></table>
<b class="navlabel">Previous:</b> <a class="sectref" HREF="node366.html" tppabs="http://www.python.org/doc/current/lib/node366.html">16.1.1 An example</A>
<b class="navlabel">Up:</b> <a class="sectref" href="restricted.html" tppabs="http://www.python.org/doc/current/lib/restricted.html">16. Restricted Execution</A>
<b class="navlabel">Next:</b> <a class="sectref" href="language.html" tppabs="http://www.python.org/doc/current/lib/language.html">17. Python Language Services</A>
</DIV>
<!--End of Navigation Panel-->
<ADDRESS>
<hr>See <i><a href="about.html" tppabs="http://www.python.org/doc/current/lib/about.html">About this document...</a></i> for information on suggesting changes.
</ADDRESS>
</BODY>
</HTML>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -