dbus-python: use home-made object as argument

[Zhang Sen]

Hi,

Can I use a custom object as the argument of dbus call, in python?
Something like,

On the caller's side,
----------
> Class Container:
>     def __init__(self, a, b, c):
>         self.a = a
>         self.b = b
>         self.c = c
> 
> proxy = bus.get_object(...)
> proxy.foo(Container(1, 2, 3))
----------

And to export the method on the other side,
----------
> @dbus.service.method(dbus_interface=my_interface,
>         in_signature="a(uuu)", out_signature="")
> def foo(self, value):
----------

No matter what I put in 'in_signature', I got the error 'Don't know how
which D-Bus type to use to encode type "instance"'.

> ERROR:dbus.connection:Unable to set arguments
> (<__main__.NumberBoxModel instance at 0x18c57e8>,) according to
> signature None:
> <type 'exceptions.TypeError'>: Don't know how which D-Bus type to use
> to encode type "instance"
> Traceback (most recent call last):
> [...]
>   File "/usr/lib64/python2.6/site-packages/dbus/proxies.py", line 140,
> in __call__
>     **keywords)
>   File "/usr/lib/python2.6/site-packages/dbus/connection.py", line
> 620, in call_blocking
>     message.append(signature=signature, *args)
> TypeError: Don't know how which D-Bus type to use to encode type
> "instance"

It's dbus-1.2.4 here. (You see the error message even has a typo).

How should I write in_signature, or am I actually thinking the right
way? Thanks.

-zhang