3.3 aepack -- Conversion between Python variables and AppleEvent data containers

3.3 aepack -- Conversion between Python variables and AppleEvent data containers

Availability: Macintosh.

The aepack 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 AEDesc, defined in module Carbon.AE.

The aepack module defines the following functions:

pack( x[, forcetype])

Returns an AEDesc object containing a conversion of Python value x. If forcetype 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:

Python type	descriptor type
`FSSpec`	typeFSS
`FSRef`	typeFSRef
`Alias`	typeAlias
integer	typeLong (32 bit integer)
float	typeFloat (64 bit floating point)
string	typeText
unicode	typeUnicodeText
list	typeAEList
dictionary	typeAERecord
instance	see below

If x is a Python instance then this function attempts to call an __aepack__() method. This method should return an AEDesc object.

If the conversion x is not defined above, this function returns the Python string representation of a value (the repr() function) encoded as a text descriptor.

unpack( x[, formodulename])

x must be an object of type AEDesc. This function returns a Python object representation of the data in the Apple Event descriptor x. 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. line 3 of document 1) are returned as instances of aetypes.ObjectSpecifier, unless formodulename is specified. AppleEvent descriptors with descriptor type typeFSS are returned as FSSpec objects. AppleEvent record descriptors are returned as Python dictionaries, with 4-character string keys and elements recursively unpacked.

The optional formodulename argument is used by the stub packages generated by gensuitemodule, 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 Finder.Window and not a generic aetypes.Window. The former knows about all the properties and elements a window has in the Finder, while the latter knows no such things.