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<H3><A NAME="SECTION006915000000000000000"></A><A NAME="stream-recoder-objects"></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>&nbsp;<tt id='l2h-1017' xml:id='l2h-1017' 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>

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