Jeremy Sanders wrote:
> Is it possible to implement some sort of "lazy" creation of objects only
> when the object is used, but behaving in the same way as the object?
>
A generic approach would override __getattribute__ to let it perform the
__init__ method on not initialized objects.This is a case for using
metaclasses as even __init__ method must be overridden ad hoc to
register the arguments for the lazy initialization.
Probably you want to fine-tune the triggering (specifing which attribute
should make it happen ),as every look up would trigger.....
class NotInitializedObjects(type):
def __init__(cls,*_):
realInit=cls.__init__
def __newInit__(self,*pos,**key):
def _init():
realInit(self,*pos,**key)
self._init=_init
cls.__init__=__newInit__
def __getattribute__(self,attr):
def getter(attr):
return object.__getattribute__(self,attr)
if '_init' in getter('__dict__'):
getter('_init')()
del self._init
return getter(attr)
cls.__getattribute__=__getattribute__
if __name__=='__main__':
class Class:
__metaclass__=NotInitializedObjects
def __init__(self,*pos,**key):
self.initialized=True
print 'initializing with',pos,key
a=Class('arg',key='key') # a fake initialization
try:
object.__getattribute__(a,'initialized')
except AttributeError: # should raise
print 'not initialized'
else:
raise
try:
a.initialized #every look up would do ,even a print
except AttributeError:
raise
else:
print 'initialized'
Have fun Paolino
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