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<H2><A NAME="SECTION0019110000000000000000"></A><A NAME="rexec-objects"></A>
<BR>
17.1.1 RExec Objects
</H2>

<P>
<tt class="class">RExec</tt> instances support the following methods:

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4914' xml:id='l2h-4914' class="method">r_eval</tt></b>(</nobr></td>
  <td><var>code</var>)</td></tr></table></dt>
<dd>
<var>code</var> must either be a string containing a Python expression, or
a compiled code object, which will be evaluated in the restricted
environment's <tt class="module">__main__</tt> module.  The value of the expression or
code object will be returned.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4915' xml:id='l2h-4915' class="method">r_exec</tt></b>(</nobr></td>
  <td><var>code</var>)</td></tr></table></dt>
<dd>
<var>code</var> must either be a string containing one or more lines of
Python code, or a compiled code object, which will be executed in the
restricted environment's <tt class="module">__main__</tt> module.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4916' xml:id='l2h-4916' class="method">r_execfile</tt></b>(</nobr></td>
  <td><var>filename</var>)</td></tr></table></dt>
<dd>
Execute the Python code contained in the file <var>filename</var> in the
restricted environment's <tt class="module">__main__</tt> module.
</dl>

<P>
Methods whose names begin with "<tt class="samp">s_</tt>" are similar to the functions
beginning with "<tt class="samp">r_</tt>", but the code will be granted access to
restricted versions of the standard I/O streams <code>sys.stdin</code>,
<code>sys.stderr</code>, and <code>sys.stdout</code>.

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4917' xml:id='l2h-4917' class="method">s_eval</tt></b>(</nobr></td>
  <td><var>code</var>)</td></tr></table></dt>
<dd>
<var>code</var> must be a string containing a Python expression, which will
be evaluated in the restricted environment.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4918' xml:id='l2h-4918' class="method">s_exec</tt></b>(</nobr></td>
  <td><var>code</var>)</td></tr></table></dt>
<dd>
<var>code</var> must be a string containing one or more lines of Python code,
which will be executed in the restricted environment.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4919' xml:id='l2h-4919' class="method">s_execfile</tt></b>(</nobr></td>
  <td><var>code</var>)</td></tr></table></dt>
<dd>
Execute the Python code contained in the file <var>filename</var> in the
restricted environment.
</dl>

<P>
<tt class="class">RExec</tt> objects must also support various methods which will be
implicitly called by code executing in the restricted environment.
Overriding these methods in a subclass is used to change the policies
enforced by a restricted environment.

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4920' xml:id='l2h-4920' class="method">r_import</tt></b>(</nobr></td>
  <td><var>modulename</var><big>[</big><var>, globals</var><big>[</big><var>,
                             locals</var><big>[</big><var>, fromlist</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Import the module <var>modulename</var>, raising an <tt class="exception">ImportError</tt>
exception if the module is considered unsafe.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4921' xml:id='l2h-4921' class="method">r_open</tt></b>(</nobr></td>
  <td><var>filename</var><big>[</big><var>, mode</var><big>[</big><var>, bufsize</var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Method called when <tt class="function">open()</tt> is called in the restricted
environment.  The arguments are identical to those of <tt class="function">open()</tt>,
and a file object (or a class instance compatible with file objects)
should be returned.  <tt class="class">RExec</tt>'s default behaviour is allow opening
any file for reading, but forbidding any attempt to write a file.  See
the example below for an implementation of a less restrictive
<tt class="method">r_open()</tt>.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4922' xml:id='l2h-4922' class="method">r_reload</tt></b>(</nobr></td>
  <td><var>module</var>)</td></tr></table></dt>
<dd>
Reload the module object <var>module</var>, re-parsing and re-initializing it.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4923' xml:id='l2h-4923' class="method">r_unload</tt></b>(</nobr></td>
  <td><var>module</var>)</td></tr></table></dt>
<dd>
Unload the module object <var>module</var> (remove it from the
restricted environment's <code>sys.modules</code> dictionary).
</dl>

<P>
And their equivalents with access to restricted standard I/O streams:

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4924' xml:id='l2h-4924' class="method">s_import</tt></b>(</nobr></td>
  <td><var>modulename</var><big>[</big><var>, globals</var><big>[</big><var>,
                             locals</var><big>[</big><var>, fromlist</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Import the module <var>modulename</var>, raising an <tt class="exception">ImportError</tt>
exception if the module is considered unsafe.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4925' xml:id='l2h-4925' class="method">s_reload</tt></b>(</nobr></td>
  <td><var>module</var>)</td></tr></table></dt>
<dd>
Reload the module object <var>module</var>, re-parsing and re-initializing it.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4926' xml:id='l2h-4926' class="method">s_unload</tt></b>(</nobr></td>
  <td><var>module</var>)</td></tr></table></dt>
<dd>
Unload the module object <var>module</var>.
</dl>

<P>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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