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<H3><A NAME="SECTION006911000000000000000"></A><A NAME="codec-objects"></A>
<BR>
4.9.1.1 Codec Objects 
</H3>

<P>
The <tt class="class">Codec</tt> class defines these methods which also define the
function interfaces of the stateless encoder and decoder:

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-1005' xml:id='l2h-1005' class="method">encode</tt></b>(</nobr></td>
  <td><var>input</var><big>[</big><var>, errors</var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
  Encodes the object <var>input</var> and returns a tuple (output object,
  length consumed).  While codecs are not restricted to use with Unicode, in
  a Unicode context, encoding converts a Unicode object to a plain string
  using a particular character set encoding (e.g., <code>cp1252</code> or
  <code>iso-8859-1</code>).

<P>
<var>errors</var> defines the error handling to apply. It defaults to
  <code>'strict'</code> handling.

<P>
The method may not store state in the <tt class="class">Codec</tt> instance. Use
  <tt class="class">StreamCodec</tt> for codecs which have to keep state in order to
  make encoding/decoding efficient.

<P>
The encoder must be able to handle zero length input and return an
  empty object of the output object type in this situation.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-1006' xml:id='l2h-1006' class="method">decode</tt></b>(</nobr></td>
  <td><var>input</var><big>[</big><var>, errors</var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
  Decodes the object <var>input</var> and returns a tuple (output object,
  length consumed).  In a Unicode context, decoding converts a plain string
  encoded using a particular character set encoding to a Unicode object.

<P>
<var>input</var> must be an object which provides the <code>bf_getreadbuf</code>
  buffer slot.  Python strings, buffer objects and memory mapped files
  are examples of objects providing this slot.

<P>
<var>errors</var> defines the error handling to apply. It defaults to
  <code>'strict'</code> handling.

<P>
The method may not store state in the <tt class="class">Codec</tt> instance. Use
  <tt class="class">StreamCodec</tt> for codecs which have to keep state in order to
  make encoding/decoding efficient.

<P>
The decoder must be able to handle zero length input and return an
  empty object of the output object type in this situation.
</dl>

<P>
The <tt class="class">StreamWriter</tt> and <tt class="class">StreamReader</tt> classes provide
generic working interfaces which can be used to implement new
encodings submodules very easily. See <tt class="module">encodings.utf_8</tt> for an
example on how this is done.

<P>

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	55	<H3><A NAME="SECTION006911000000000000000"></A><A NAME="codec-objects"></A>
	56	<BR>
	57	4.9.1.1 Codec Objects
	58	</H3>
	59
	60	<P>
	61	The <tt class="class">Codec</tt> class defines these methods which also define the
	62	function interfaces of the stateless encoder and decoder:
	63
	64	<P>
65	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
66	<td><nobr><b><tt id='l2h-1005' xml:id='l2h-1005' class="method">encode</tt></b>(</nobr></td>
67	<td><var>input</var><big>[</big><var>, errors</var><big>]</big><var></var>)</td></tr></table></dt>
68	<dd>
69	Encodes the object <var>input</var> and returns a tuple (output object,
70	length consumed). While codecs are not restricted to use with Unicode, in
71	a Unicode context, encoding converts a Unicode object to a plain string
72	using a particular character set encoding (e.g., <code>cp1252</code> or
73	<code>iso-8859-1</code>).
74
75	<P>
76	<var>errors</var> defines the error handling to apply. It defaults to
77	<code>'strict'</code> handling.
78
79	<P>
80	The method may not store state in the <tt class="class">Codec</tt> instance. Use
81	<tt class="class">StreamCodec</tt> for codecs which have to keep state in order to
82	make encoding/decoding efficient.
83
84	<P>
85	The encoder must be able to handle zero length input and return an
86	empty object of the output object type in this situation.
87	</dl>
88
89	<P>
90	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
91	<td><nobr><b><tt id='l2h-1006' xml:id='l2h-1006' class="method">decode</tt></b>(</nobr></td>
92	<td><var>input</var><big>[</big><var>, errors</var><big>]</big><var></var>)</td></tr></table></dt>
93	<dd>
94	Decodes the object <var>input</var> and returns a tuple (output object,
95	length consumed). In a Unicode context, decoding converts a plain string
96	encoded using a particular character set encoding to a Unicode object.
97
98	<P>
99	<var>input</var> must be an object which provides the <code>bf_getreadbuf</code>
100	buffer slot. Python strings, buffer objects and memory mapped files
101	are examples of objects providing this slot.
102
103	<P>
104	<var>errors</var> defines the error handling to apply. It defaults to
105	<code>'strict'</code> handling.
106
107	<P>
108	The method may not store state in the <tt class="class">Codec</tt> instance. Use
109	<tt class="class">StreamCodec</tt> for codecs which have to keep state in order to
110	make encoding/decoding efficient.
111
112	<P>
113	The decoder must be able to handle zero length input and return an
114	empty object of the output object type in this situation.
115	</dl>
116
117	<P>
118	The <tt class="class">StreamWriter</tt> and <tt class="class">StreamReader</tt> classes provide
119	generic working interfaces which can be used to implement new
120	encodings submodules very easily. See <tt class="module">encodings.utf_8</tt> for an
121	example on how this is done.
122
123	<P>
124
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