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<H2><A NAME="SECTION004230000000000000000">
2.2.3 Attribute Management</A>
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<P>
For every object which can support attributes, the corresponding type
must provide the functions that control how the attributes are
resolved.  There needs to be a function which can retrieve attributes
(if any are defined), and another to set attributes (if setting
attributes is allowed).  Removing an attribute is a special case, for
which the new value passed to the handler is <tt class="constant">NULL</tt>.

<P>
Python supports two pairs of attribute handlers; a type that supports
attributes only needs to implement the functions for one pair.  The
difference is that one pair takes the name of the attribute as a
<tt class="ctype">char*</tt>, while the other accepts a <tt class="ctype">PyObject*</tt>.  Each type
can use whichever pair makes more sense for the implementation's
convenience.

<P>
<div class="verbatim"><pre>
    getattrfunc  tp_getattr;        /* char * version */
    setattrfunc  tp_setattr;
    /* ... */
    getattrofunc tp_getattrofunc;   /* PyObject * version */
    setattrofunc tp_setattrofunc;
</pre></div>

<P>
If accessing attributes of an object is always a simple operation
(this will be explained shortly), there are generic implementations
which can be used to provide the <tt class="ctype">PyObject*</tt> version of the
attribute management functions.  The actual need for type-specific
attribute handlers almost completely disappeared starting with Python
2.2, though there are many examples which have not been updated to use
some of the new generic mechanism that is available.

<P>

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