[maemo-developers] [pymaemo] Python-mafw overrides

[From: Anderson Lizardo]

On Tue, Jul 21, 2009 at 7:12 AM, Andrea Grandi<a.grandi at gmail.com> wrote:
> could you please make me an example of a method that needs to be overridden?

Sorry, but I don't have a precise example of a method to override.
This is usually done on demand.

One hint is that you can check the methods shown as warnings when you
build the module. I think I sent you a list of these earlier. They
appear as one of:

Could not write method <Class.method>: No ArgType for <some type>
Could not write function <function>: No ArgType for <some type>

It means that codegen does not know about type <some type> and thus
requires some override to implement that method or function.

>
> Now I've read all this page: http://docs.python.org/extending/newtypes.html
> about how to define custom objects/types... I hope to be able to
> understand better how the whole thing works.

It's good to know how it works, but probably you will not to do that
by hand (codegen takes care of registering even custom types).

I also suggest you building the current module and taking a look at
the generated mafw.c. It is very readable, and can even serve as
skeleton if one wants to create a Python extension by hand.

> If you tell me another method that need to be overridden (and why)
> I'll try to override it, then I'll send you the code.

You can take a look at one of those I mentioned. Note that I'm working
on some of those myself, more specifically the ones related to the
MafwPlaylist and MafwPlaylistManager classes.

Other (simpler) cases are those like mafw_registry_get_instance():
functions that always return the same object (instead of a new object)
and thus need to become a static Python method. For these functions,
you add a line like this to the mafw_gen_defs.sh:

to_method defs/mafw-registry.defs mafw_registry_get_instance
get_instance MafwRegistry

and the corresponding snippet on mafw.override (you can use the
get_instance() as base.

Regards,
-- 
Anderson Lizardo
OpenBossa Labs - INdT
Manaus - Brazil