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<h3>Miscellaneous Modules</h3>
<p>The modules in this category are used for miscellaneous tasks that don抰 fit into any of the other categories.</p>
<H4><TT Class="monofont">bisect</TT></H4>
<P>The <tt clASS="monofont">bisect</Tt> module provides support for keeping lists in sorted order. It uses a bisection algorithm to do most of its work.</p>
<pre>
<b>bisect(</b><b><i>list</i></b><b>,</b> <b><i>item</i></b> <b>[,</b> <b><I>low</i></b> <B>[,</b> <b><i>high</I></b><b>]])</b> </pRe>
<p>Returns the index of the proper insertion point for <i><TT CLass="monofont">item</tT></I>
to be placed in <I><Tt claSS="monofont">list</TT></i>
in order to maintain <i><tt CLASs="monofont">list</tt></i>
in sorted order. <i><tt class="monofont">low</tt></i>
and <i><tt clAss="monofont">high</Tt></i>
are indices specifying a subset of the list to be considered.</p>
<Pre>
<b>insort(</b><B><i>list</i></b><B>,</B> <B><I>item</i></b> <b>[,</b> <B><I>low</I></B> <b>[,</b> <b><i>high</I></B><B>]])</B> </pre>
<p>Inserts <I><TT Class="monofont">item</tt></i>
into <i><tt class="monofont">list</tt></i>
in sorted order.</p>
<a NamE="4"></a>
<h4><tT clasS="monofont">cmd</tt></h4>
<P>The <TT Class="monofont">cmd</TT> module provides a class <TT clasS="monofont">Cmd</TT> that抯 used as a framework for building a line-oriented command interpreter. The <Tt claSS="monofont">Cmd</TT> class is never instantiated directly, but is used as a base class for a class that actually implements the interpreter. An instance <i><tt class="monofont">c</tt></i>
of the <tt class="monofont">Cmd</tt> class provides the following methods:</P>
<prE>
<b><i>c</i></B><b>.cmdloop([</b><b><i>intro</I></b><b>])</b> </PRE>
<P>Prints a banner message contained in <i><tt cLASS="monofont">intro</tt></i>
and repeatedly issues a prompt, reads a line of input, and dispatches an appropriate action. For each line of text, the first word is stripped off and used as a command name. For a command name of <tT CLAss="monofont">'foo'</tt>, an attempt is made to invoke a method <TT CLass="monofont">do_foo()</tt> with the remainder of the input line as a string argument. If a line contains only the character <tt class="monofont">'?'</tt>, a predefined method <tt clasS="monofont">do_help()</tt> is dispatched. If the command name is <Tt clAss="monofont">'!'</tt>, a method <Tt clASS="monofont">do_shell()</Tt> is invoked (if defined). An end-of-file is converted into a string <tt cLASS="monofont">'EOF'</tt> and dispatched to a command <tt CLASs="monofont">do_EOF</tt>.</p>
<P>Subclasses of <TT Class="monofont">Cmd</tt> inherit a predefined method <tt class="monofont">do_help()</tt>. When this method is invoked with an argument <tt claSs="monofont">'bar'</tT>, it tries to invoke the method <tt cLass="monofont">help_bar()</tT>. With no arguments, <tt cLASS="monofont">do_help()</tt> lists all the available help topics by listing all commands with corresponding <tt CLASs="monofont">help_*</tt> methods, undocumented commands (commands without corresponding <tT CLAss="monofont">help_*</tt> methods), and miscellaneous topics (help methods without a corresponding command). Each of the command methods should return an integer code indicating success or failure. A negative value indicates an error and causes the interpreter to return. Otherwise, the interpreter continues to read input after each command. If the <TT CLass="monofont">readline</tt> module has been loaded, the command interpreter will have line editing and history capabilities.</p>
<pre>
<b><i>c</i></b><b>.onecmd(</b><b><i>str</i></b><b>)</B> </prE>
<p>Interprets <i><tT clasS="monofont">str</tt></i>
as a single line of input.</P>
<PRE>
<b><i>c</i></b><B>.emptyline()</B> </PRe>
<p>This method is called when an empty line of input is typed. It should be defined by the user. If not overridden, it repeats the last nonempty command entered.</p>
<pRE>
<B><I>c</i></b><b>.default(</b><B><I>line</I></B><b>)</b> </pre>
<p>Called when an unrecognized command is typed. By default, it prints an error message and exits.</p>
<pre>
<b><i>c</i></b><b>.precmd()</b> </pre>
<p>Method executed just before the input prompt is issued. It should be overridden by derived classes.</P>
<prE>
<b><i>c</i></B><b>.postcmd()</b> </prE>
<p>Method executed immediately after a command dispatch has finished.</p>
<pRE>
<B><I>c</i></b><b>.preloop()</b> </PRE>
<P>Method executed once when <tt clASS="monofont">cmdloop()</Tt> is executed.</p>
<prE>
<B><I>c</I></b><b>.postloop()</b> </pre>
<p>Method executed when <tt class="monofont">cmdloop()</tt> is about to return.</p>
<p>The following instance variables should also be defined by a subclass of <tt ClaSs="monofont">Cmd</tt>.</P>
<p><tabLe boRDER="1" cellSPACing="0" cELLPaddiNG="1" WIdth="100%">
<colgroup span="2">
<tr>
<th vAliGn="top">
<foNt sizE="2">
<p><b>Variable</b></P>
</FONt></th>
<tH VALign="top">
<fONT Size="2">
<p><B>Description</B></P>
</Font></th>
</tr>
<tr>
<td valign="top">
<fonT siZe="2">
<p><i><Tt claSs="monofont">c</tt></I>
<TT Class="monofont">.prompt</TT></P>
</Font></tD>
<TD ValigN="top">
<FONt size="2">
<p>Prompt printed to solicit input.</p>
</font></td>
</tr>
<tr>
<td vAliGn="top">
<foNt sizE="2">
<p><i><tT CLAss="monofont">c</tt></I>
<TT Class="monofont">.identchars</TT></P>
</Font></tD>
<TD Valign="top">
<font size="2">
<p>String of characters accepted for the command prefix.</p>
</font></tD>
</tr>
<Tr>
<td ValigN="top">
<fonT SIZe="2">
<p><i><tT CLAss="monofont">c</tt></I>
<TT Class="monofont">.lastcmd</TT></P>
</Font></td>
<td valign="top">
<font sizE="2">
<p>Last nonempty command seen.</p>
</Font></Td>
</tr>
<tR>
<td vALIGn="top">
<fonT SIZe="2">
<p><i><tT CLAss="monofont">c</tt></I>
<TT Class="monofont">.intro</tt></p>
</font></td>
<td valigN="top">
<foNt siZe="2">
<p>Intro text banner; overridden using the argument to <tt ClasS="monofont">cmdloop()</TT>.</P>
</font></TD>
</TR>
<tr>
<td VALIgn="top">
<foNT SIze="2">
<p><i><tt class="monofont">c</tt></i>
<tt clasS="monofont">.doc_header</tt></P>
</fonT></td>
<td ValiGN="top">
<FOnt siZE="2">
<P>Header to issue if the help section has a section for documented commands.</P>
</font></TD>
</TR>
<tr>
<td VALIgn="top">
<font size="2">
<p><i><tt class="monofont">c</tT></i>
<tT claSs="monofont">.misc_header</tt></p>
</Font></TD>
<TD valiGN="top">
<FOnt siZE="2">
<P>Header to issue for miscellaneous help topics.</P>
</font></TD>
</TR>
<tr>
<td valign="top">
<font size="2">
<p><i><Tt cLass="monofont">c</Tt></i>
<tt ClasS="monofont">.undoc_header</TT></P>
</font></TD>
<TD valiGN="top">
<FOnt siZE="2">
<P>Header for undocumented commands.</P>
</font></td>
</tr>
<tr>
<td valign="top">
<foNt sIze="2">
<p><I><tt clAss="monofont">c</tT></I>
<TT clasS="monofont">.ruler</TT></P>
</font></TD>
<TD valiGN="top">
<FOnt size="2">
<p>Character used to draw separator lines under help message headers. If empty, no ruler line is drawn. The default is <tt class="monofont">'='</tt>.</p>
</fonT></td>
</Tr>
</coLgrouP>
</tabLE></P>
<H5>Example</h5>
<p>The following example shows how this module can be used to implement an interpreter wrapper around the callable objects of a module. It also shows the interesting feature of code being executed in a class definition.</p>
<pRE>
# cmdhelp.py
# Builds a command interpreter that allows arbitrary Python
# commands to be typed, but reads their doc strings to create
# a collection of help commands. Just do an execfile(cmdhelp.py)
# in a module to utilize this.
import cmd, sys, traceback
# Define the interpreter class
class Interpreter(cmd.Cmd):
symbols = globals()
prompt = "?>> "
intro = "Interpreter for " + _ _name_ _
# Find all of the callable objects and look for
# their doc strings
for n in symbols.keys():
c = symbols[n]
if callable(c):
if c._ _doc_ _:
exec """
def help_%s(self):print %s._ _doc_ _
""" % (n,n)
# Execute an arbitrary statement
def default(self,l):
try:
exec self.lastcmd in globals()
except:
traceback.print_exc()
# Do nothing on empty line
def emptyline(self):
pass
def do_EOF(self,arg):
return -1
# Create an instance
interp = Interpreter() </PRe>
<p>The following code shows how this code might be used:</p>
<pRE>
Python 2.0 (#1, Feb 25 2001, 07:54:16)
[GCC 2.95.2 19991024 (release)] on sunos5
Type "copyright", "credits" or "license" for more information.
>>> from socket import *
>>> execfile("cmdhelp.py")
>>> interp.cmdloop()
Interpreter for _ _main_ _
?>> help
Miscellaneous help topics:
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