[PyKDE] Embedding PyQt apps in non-PyQt python programs

[Jeremy Sanders]

Hi -

I've written a module other PyQt users may find useful. It embeds my PyQt 
based plotting package, Veusz, in non-PyQt python apps. The non-PyQt 
code can communicate with the PyQt code as if there wasn't an event 
loop. It exposes Veusz's scripting language as methods of an object.

http://cvs.gna.org/viewcvs/veusz/veusz/embed.py?rev=HEAD&content-type=text/vnd.viewcvs-markup

It works by starting PyQt in a second python thread. A new instance of the 
class creates a new PyQt window. When a method is called, __getattr__ is 
used to "wrap" the method which is passed to the PyQt thread. It does this 
by writing a character to a pipe. The PyQt QApplication uses 
QSocketNotifier to catch the character, read the method and its arguments 
from a variable and call it. Return values or exceptions are passed back 
to the primary thread (with the help of another pipe for synchronisation). 
Any exceptions are rethrown in the primary thread, or values are returned 
from the method wrapper.

It all seems to work pretty well, except that __del__ never appears to be 
called on the wrapper instances. Presumably something is keeping a 
reference to the objects, but I haven't tracked it down yet...

Jeremy

-- 
Jeremy Sanders <jeremy at jeremysanders.net>
http://www.jeremysanders.net/                Cambridge, UK
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