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<H2><A NAME="SECTION005350000000000000000"></A>
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3.3.5 Additional methods for emulation of sequence types
  
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<P>
The following methods can be defined to further emulate sequence
objects.  Immutable sequences methods should only define
<tt class=method>__getslice__()</tt>; mutable sequences, should define all three
three methods.

<P>
<dl><dt><b><a name="l2h-351"><tt class=method>__getslice__</tt></a></b> (<var>self, i, j</var>)
<dd>
Called to implement evaluation of <tt><var>self</var>[<var>i</var>:<var>j</var>]</tt>.
The returned object should be of the same type as <var>self</var>.  Note
that missing <var>i</var> or <var>j</var> in the slice expression are replaced
by zero or <tt>sys.maxint</tt>, respectively, and no further
transformations on the indices is performed.  The interpretation of
negative indices and indices larger than the length of the sequence is
up to the method.
</dl>

<P>
<dl><dt><b><a name="l2h-352"><tt class=method>__setslice__</tt></a></b> (<var>self, i, j, sequence</var>)
<dd>
Called to implement assignment to <tt><var>self</var>[<var>i</var>:<var>j</var>]</tt>.
Same notes for <var>i</var> and <var>j</var> as for <tt class=method>__getslice__()</tt>.
</dl>

<P>
<dl><dt><b><a name="l2h-353"><tt class=method>__delslice__</tt></a></b> (<var>self, i, j</var>)
<dd>
Called to implement deletion of <tt><var>self</var>[<var>i</var>:<var>j</var>]</tt>.
Same notes for <var>i</var> and <var>j</var> as for <tt class=method>__getslice__()</tt>.
</dl>

<P>
Notice that these methods are only invoked when a single slice with a
single colon is used.  For slice operations involving extended slice
notation, <tt class=method>__getitem__()</tt>, <tt class=method>__setitem__()</tt>
or<tt class=method>__delitem__()</tt> is called.

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