|  | Help Understanding weakref (lazyloader) | | |
| | | Ripter |  |
|  Posted: Thu Sep 04, 2008 2:46 am Post subject: Help Understanding weakref (lazyloader) |  |
I found this script at LINK
And I can't quite figure out how it works. I was wondering if someone
could clarify it for me.
The Code is:
import pygame
import weakref
class ResourceController(object):
def __init__(self, loader):
self.__dict__.update(dict(
names = {},
cache = weakref.WeakValueDictionary(),
loader = loader
))
def __setattr__(self, name, value):
self.names[name] = value
def __getattr__(self, name):
try:
img = self.cache[name]
except KeyError:
img = self.loader(self.names[name])
self.cache[name] = img
return img
class ImageController(ResourceController):
def __init__(self):
ResourceController.__init__(self, pygame.image.load)
My question is why does the __setattr__ set the value to
self.names[name] instead of self.cache[name]? |
| |
| | | Ripter | |
| | Posted: Thu Sep 04, 2008 3:04 am Post subject: Re: Help Understanding weakref (lazyloader) | |
| |  | |
On Sep 3, 10:46 pm, Ripter <Ripter...@gmail.com> wrote:
| Quote: | I found this script LINK
And I can't quite figure out how it works. I was wondering if someone
could clarify it for me.
The Code is:
import pygame
import weakref
class ResourceController(object):
def __init__(self, loader):
self.__dict__.update(dict(
names = {},
cache = weakref.WeakValueDictionary(),
loader = loader
))
def __setattr__(self, name, value):
self.names[name] = value
def __getattr__(self, name):
try:
img = self.cache[name]
except KeyError:
img = self.loader(self.names[name])
self.cache[name] = img
return img
class ImageController(ResourceController):
def __init__(self):
ResourceController.__init__(self, pygame.image.load)
My question is why does the __setattr__ set the value to
self.names[name] instead of self.cache[name]?
|
I feel stupid, I figured it out. (Don't program while watching Back to
the Future)
The reason would be the 'lazy' part. self.names holds the file name,
and when you get the property back (__getattr__) it checks to see if
it already got the value or not, and uses the name to get the value if
it hasn't already.
Duh. Sorry. |
| |
|
|
