<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<link rel="STYLESHEET" href="lib.css" type='text/css' />
<link rel="SHORTCUT ICON" href="../icons/pyfav.gif" />
<link rel='start' href='../index.html' title='Python Documentation Index' />
<link rel="first" href="lib.html" title='Python Library Reference' />
<link rel='contents' href='contents.html' title="Contents" />
<link rel='index' href='genindex.html' title='Index' />
<link rel='last' href='about.html' title='About this document...' />
<link rel='help' href='about.html' title='About this document...' />
<LINK rel="prev" href="stream-reader-writer.html">
<LINK rel="parent" href="node121.html">
<LINK rel="next" href="node127.html">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<meta name='aesop' content='information' />
<META name="description" content="StreamRecoder Objects ">
<META name="keywords" content="lib">
<META name="resource-type" content="document">
<META name="distribution" content="global">
<title>4.9.1.5 StreamRecoder Objects </title>
</head>
<body>
<DIV CLASS="navigation">
<div id='top-navigation-panel'>
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="4.9.1.4 StreamReaderWriter Objects"
href="stream-reader-writer.html"><img src='../icons/previous.png'
border='0' height='32' alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="4.9.1 Codec Base Classes"
href="node121.html"><img src='../icons/up.png'
border='0' height='32' alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="4.9.2 Standard Encodings"
href="node127.html"><img src='../icons/next.png'
border='0' height='32' alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
href="contents.html"><img src='../icons/contents.png'
border='0' height='32' alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
border='0' height='32' alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
href="genindex.html"><img src='../icons/index.png'
border='0' height='32' alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="stream-reader-writer.html">4.9.1.4 StreamReaderWriter Objects</A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="node121.html">4.9.1 Codec Base Classes</A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="node127.html">4.9.2 Standard Encodings</A>
</div>
<hr /></div>
</DIV>
<!--End of Navigation Panel-->
<H3><A NAME="SECTION006915000000000000000"><!--x--></A><A NAME="stream-recoder-objects"><!--z--></A>
<BR>
4.9.1.5 StreamRecoder Objects
</H3>
<P>
The <tt class="class">StreamRecoder</tt> provide a frontend - backend view of
encoding data which is sometimes useful when dealing with different
encoding environments.
<P>
The design is such that one can use the factory functions returned by
the <tt class="function">lookup()</tt> function to construct the instance.
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><span class="typelabel">class</span> <tt id='l2h-976' class="class">StreamRecoder</tt></b>(</nobr></td>
<td><var>stream, encode, decode,
Reader, Writer, errors</var>)</td></tr></table></dt>
<dd>
Creates a <tt class="class">StreamRecoder</tt> instance which implements a two-way
conversion: <var>encode</var> and <var>decode</var> work on the frontend (the
input to <tt class="method">read()</tt> and output of <tt class="method">write()</tt>) while
<var>Reader</var> and <var>Writer</var> work on the backend (reading and
writing to the stream).
<P>
You can use these objects to do transparent direct recodings from
e.g. Latin-1 to UTF-8 and back.
<P>
<var>stream</var> must be a file-like object.
<P>
<var>encode</var>, <var>decode</var> must adhere to the <tt class="class">Codec</tt>
interface, <var>Reader</var>, <var>Writer</var> must be factory functions or
classes providing objects of the <tt class="class">StreamReader</tt> and
<tt class="class">StreamWriter</tt> interface respectively.
<P>
<var>encode</var> and <var>decode</var> are needed for the frontend
translation, <var>Reader</var> and <var>Writer</var> for the backend
translation. The intermediate format used is determined by the two
sets of codecs, e.g. the Unicode codecs will use Unicode as
intermediate encoding.
<P>
Error handling is done in the same way as defined for the
stream readers and writers.
</dl>
<P>
<tt class="class">StreamRecoder</tt> instances define the combined interfaces of
<tt class="class">StreamReader</tt> and <tt class="class">StreamWriter</tt> classes. They inherit
all other methods and attribute from the underlying stream.
<P>
<DIV CLASS="navigation">
<div class='online-navigation'><hr />
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="4.9.1.4 StreamReaderWriter Objects"
rel="prev" title="4.9.1.4 StreamReaderWriter Objects"
href="stream-reader-writer.html"><img src='../icons/previous.png'
border='0' height='32' alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="4.9.1 Codec Base Classes"
rel="parent" title="4.9.1 Codec Base Classes"
href="node121.html"><img src='../icons/up.png'
border='0' height='32' alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="4.9.2 Standard Encodings"
rel="next" title="4.9.2 Standard Encodings"
href="node127.html"><img src='../icons/next.png'
border='0' height='32' alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
rel="contents" title="Table of Contents"
href="contents.html"><img src='../icons/contents.png'
border='0' height='32' alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
border='0' height='32' alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
rel="index" title="Index"
href="genindex.html"><img src='../icons/index.png'
border='0' height='32' alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="stream-reader-writer.html">4.9.1.4 StreamReaderWriter Objects</A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="node121.html">4.9.1 Codec Base Classes</A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="node127.html">4.9.2 Standard Encodings</A>
</div>
</div>
<hr />
<span class="release-info">Release 2.3.4, documentation updated on May 20, 2004.</span>
</DIV>
<!--End of Navigation Panel-->
<ADDRESS>
See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
</ADDRESS>
</BODY>
</HTML>
