On Thu, Jul 14, 2011 at 10:05 AM, DR0ID <[email protected]> wrote:
> **
> On 14.07.2011 16:18, [email protected] wrote:
>
> Hey guys,
>
> I have a class which inherits from pygame.Surface. If the class gets
> created with a tuple, I create a new surface by calling
> pygame.Surface.__init__, so my class will work as a pygame.Surface object.
> I also need this class to be created with existing pygame.Surface
> objects. So, if I pass in a pygame.Surface object to my class, how can I get
> my class to be treated as a pygame.Surface object? Do pygame.Surface objects
> store their data in an accessible variable such as _image, in which case I
> presume I could copy the Surface._image to self._image to get the desired
> effect?
>
> Thanks,
> Sam Bull
>
>
>
> Hi
>
> An old experiment of mine, it might give you a clue how you can do it
> (actually it replaces the pygame Surface object with the SurfaceObject
> class):
>
>
> https://python-pyknic.googlecode.com/svn/branches/pyknic-2.0/experimental/surfaceobject.py
>
>
> Hope it helps.
>
> ~DR0ID
>
Hi Sam,
If all you need is access to pygame.Surface's methods and data (and not type
info like issubclass() or isinstance()) I would recommend against inheriting
from a library class (especially one written in Python's C API, as I suspect
pygame.Surface is) and instead use this hack:
# Python 2.x code
class MySurface(object):
def __init__(self, obj):
if isinstance(obj, tuple):
self._surf = pygame.Surface(*tuple)
elif isinstance(obj, pygame.Surface):
self._surf = obj
def __getattr__(self, attr):
return getattr(self._surf, attr)
The __getattr__ method is invoked whenever an instance field isn't found the
usual way. So, if you have a MySurface object called "s", this wouldn't
invoke __getattr__:
assert s.__init__
But this would:
assert s.convert
And calling s.convert() would still function as normal, because its self
parameter is actually bound to s._surf.
Hope that helps,
--
Michael
