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| 54 | <H3><A NAME="SECTION006915000000000000000"></A><A NAME="stream-recoder-objects"></A> |
| 55 | <BR> |
| 56 | 4.9.1.5 StreamRecoder Objects |
| 57 | </H3> |
| 58 | |
| 59 | <P> |
| 60 | The <tt class="class">StreamRecoder</tt> provide a frontend - backend view of |
| 61 | encoding data which is sometimes useful when dealing with different |
| 62 | encoding environments. |
| 63 | |
| 64 | <P> |
| 65 | The design is such that one can use the factory functions returned by |
| 66 | the <tt class="function">lookup()</tt> function to construct the instance. |
| 67 | |
| 68 | <P> |
| 69 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 70 | <td><nobr><b><span class="typelabel">class</span> <tt id='l2h-1017' xml:id='l2h-1017' class="class">StreamRecoder</tt></b>(</nobr></td> |
| 71 | <td><var>stream, encode, decode, |
| 72 | Reader, Writer, errors</var>)</td></tr></table></dt> |
| 73 | <dd> |
| 74 | Creates a <tt class="class">StreamRecoder</tt> instance which implements a two-way |
| 75 | conversion: <var>encode</var> and <var>decode</var> work on the frontend (the |
| 76 | input to <tt class="method">read()</tt> and output of <tt class="method">write()</tt>) while |
| 77 | <var>Reader</var> and <var>Writer</var> work on the backend (reading and |
| 78 | writing to the stream). |
| 79 | |
| 80 | <P> |
| 81 | You can use these objects to do transparent direct recodings from |
| 82 | e.g. Latin-1 to UTF-8 and back. |
| 83 | |
| 84 | <P> |
| 85 | <var>stream</var> must be a file-like object. |
| 86 | |
| 87 | <P> |
| 88 | <var>encode</var>, <var>decode</var> must adhere to the <tt class="class">Codec</tt> |
| 89 | interface, <var>Reader</var>, <var>Writer</var> must be factory functions or |
| 90 | classes providing objects of the <tt class="class">StreamReader</tt> and |
| 91 | <tt class="class">StreamWriter</tt> interface respectively. |
| 92 | |
| 93 | <P> |
| 94 | <var>encode</var> and <var>decode</var> are needed for the frontend |
| 95 | translation, <var>Reader</var> and <var>Writer</var> for the backend |
| 96 | translation. The intermediate format used is determined by the two |
| 97 | sets of codecs, e.g. the Unicode codecs will use Unicode as |
| 98 | intermediate encoding. |
| 99 | |
| 100 | <P> |
| 101 | Error handling is done in the same way as defined for the |
| 102 | stream readers and writers. |
| 103 | </dl> |
| 104 | |
| 105 | <P> |
| 106 | <tt class="class">StreamRecoder</tt> instances define the combined interfaces of |
| 107 | <tt class="class">StreamReader</tt> and <tt class="class">StreamWriter</tt> classes. They inherit |
| 108 | all other methods and attribute from the underlying stream. |
| 109 | |
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