ctypes pointers and SendMessage

[Metalone]

I would like to call
windll.user32.S endMessageA(hwn d, win32con.WM_COM MAND, wParam, lParam)
where
lParam represents a pointer to an object.

And also convert this pointer back to an object reference inside of
wnd_proc
def wnd_proc(hwnd, msg, wParam, lParam):

So something like this:
class X(Structure):
def __init__(self, x):
self.v = x

x = X(1)
windll.user32.S endMessageA(hwn d, WM_COMMAND, 4000, addressof(x))

def wnd_proc(hwnd, msg, wParam, lParam):
if msg == WM_COMMAND and wParam == 4000):
x = X.from_address( lParam)
print x.v

Unfortunately, this does not work.

Also to my surprise the following does not work:
x1 = X(1)
x2 = X.from_address( addressof(x1))
addressof(x1) == addressof(x2) --> True
but
x2.v --> 'object has no attribute v'
x1.v --> 1

Also this does not work as I expect.
p = pointer(x)
p[0].v --> 'object has no attribute v'.

What am I doing wrong?

[Michele Petrazzo]

Re: ctypes pointers and SendMessage

Metalone wrote:[color=blue]
> I would like to call
> windll.user32.S endMessageA(hwn d, win32con.WM_COM MAND, wParam, lParam)
> where
> lParam represents a pointer to an object.[/color]

and the others?
[color=blue]
>
> And also convert this pointer back to an object reference inside of
> wnd_proc
> def wnd_proc(hwnd, msg, wParam, lParam):
>
> So something like this:
> class X(Structure):
> def __init__(self, x):
> self.v = x
>
> What am I doing wrong?
>[/color]


I don't know if you want to create a "real" C structure. If yes this is
the wrong method:
[color=blue][color=green][color=darkred]
>>> class X(Structure):[/color][/color][/color]
.... _fields_ = [("x", c_int), ]
....[color=blue][color=green][color=darkred]
>>> x1 = X(1)
>>> x1.x[/color][/color][/color]
1[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

http://starship.python.net/crew/thel.../tutorial.html ->
Structures and Unions

Michele

[Metalone]

Re: ctypes pointers and SendMessage

Ok, I see what I did wrong.
I forgot to define the _fields_ variable.