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<H1><A NAME="SECTION005300000000000000000">
3.3 <tt class="module">aepack</tt> --
Conversion between Python variables and AppleEvent data containers</A>
</H1>
<P>
<A NAME="module-aepack"><!--z--></A>
<p class="availability">Availability: <span
class="platform">Macintosh</span>.</p>
<P>
The <tt class="module">aepack</tt> module defines functions for converting (packing)
Python variables to AppleEvent descriptors and back (unpacking).
Within Python the AppleEvent descriptor is handled by Python objects
of built-in type <tt class="class">AEDesc</tt>, defined in module <tt class="module"><a href="module-Carbon.AE.html">Carbon.AE</a></tt>.
<P>
The <tt class="module">aepack</tt> module defines the following functions:
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-157' class="function">pack</tt></b>(</nobr></td>
<td><var>x</var><big>[</big><var>, forcetype</var><big>]</big>)</td></tr></table></dt>
<dd>
Returns an <tt class="class">AEDesc</tt> object containing a conversion of Python
value x. If <var>forcetype</var> is provided it specifies the descriptor
type of the result. Otherwise, a default mapping of Python types to
Apple Event descriptor types is used, as follows:
<P>
<table border align="center" style="border-collapse: collapse">
<thead>
<tr class="tableheader">
<th align="left"><b>Python type</b> </th>
<th align="left"><b>descriptor type</b> </th>
</tr>
</thead>
<tbody valign="baseline">
<tr><td align="left" valign="baseline"><tt class="class">FSSpec</tt></td>
<td align="left">typeFSS</td>
<tr><td align="left" valign="baseline"><tt class="class">FSRef</tt></td>
<td align="left">typeFSRef</td>
<tr><td align="left" valign="baseline"><tt class="class">Alias</tt></td>
<td align="left">typeAlias</td>
<tr><td align="left" valign="baseline">integer</td>
<td align="left">typeLong (32 bit integer)</td>
<tr><td align="left" valign="baseline">float</td>
<td align="left">typeFloat (64 bit floating point)</td>
<tr><td align="left" valign="baseline">string</td>
<td align="left">typeText</td>
<tr><td align="left" valign="baseline">unicode</td>
<td align="left">typeUnicodeText</td>
<tr><td align="left" valign="baseline">list</td>
<td align="left">typeAEList</td>
<tr><td align="left" valign="baseline">dictionary</td>
<td align="left">typeAERecord</td>
<tr><td align="left" valign="baseline">instance</td>
<td align="left"><i>see below</i></td></tbody>
</table>
<P>
If <var>x</var> is a Python instance then this function attempts to call an
<tt class="method">__aepack__()</tt> method. This method should return an
<tt class="class">AEDesc</tt> object.
<P>
If the conversion <var>x</var> is not defined above, this function returns
the Python string representation of a value (the repr() function)
encoded as a text descriptor.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-158' class="function">unpack</tt></b>(</nobr></td>
<td><var>x</var><big>[</big><var>, formodulename</var><big>]</big>)</td></tr></table></dt>
<dd>
<var>x</var> must be an object of type <tt class="class">AEDesc</tt>. This function
returns a Python object representation of the data in the Apple
Event descriptor <var>x</var>. Simple AppleEvent data types (integer,
text, float) are returned as their obvious Python counterparts.
Apple Event lists are returned as Python lists, and the list
elements are recursively unpacked. Object references
(ex. <code>line 3 of document 1</code>) are returned as instances of
<tt class="class">aetypes.ObjectSpecifier</tt>, unless <code>formodulename</code>
is specified. AppleEvent descriptors with
descriptor type typeFSS are returned as <tt class="class">FSSpec</tt>
objects. AppleEvent record descriptors are returned as Python
dictionaries, with 4-character string keys and elements recursively
unpacked.
<P>
The optional <code>formodulename</code> argument is used by the stub packages
generated by <tt class="module">gensuitemodule</tt>, and ensures that the OSA classes
for object specifiers are looked up in the correct module. This ensures
that if, say, the Finder returns an object specifier for a window
you get an instance of <code>Finder.Window</code> and not a generic
<code>aetypes.Window</code>. The former knows about all the properties
and elements a window has in the Finder, while the latter knows
no such things.
</dl>
<P>
<div class="seealso">
<p class="heading"><b>See Also:</b></p>
<dl compact class="seemodule">
<dt>Module <b><tt class="module"><a href="module-Carbon.AE.html">Carbon.AE</a></tt>:</b>
<dd>Built-in access to Apple Event Manager routines.
</dl>
<dl compact class="seemodule">
<dt>Module <b><tt class="module"><a href="module-aetypes.html">aetypes</a></tt>:</b>
<dd>Python definitions of codes for Apple Event
descriptor types.
</dl>
<dl compact class="seetitle">
<dt><em class="citetitle"><a href="http://developer.apple.com/techpubs/mac/IAC/IAC-2.html"
>
Inside Macintosh: Interapplication
Communication</a></em></dt>
<dd>Information about inter-process
communications on the Macintosh.</dd>
</dl>
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<span class="release-info">Release 2.3.4, documentation updated on May 20, 2004.</span>
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