On Wednesday, January 22, 2014 6:18:57 PM UTC+2, Chris Angelico wrote:
> On Thu, Jan 23, 2014 at 3:07 AM, Asaf Las <[email protected]> wrote:
> > is it possible to create singleton using construct below :
> >
> > def singleton_provider(x = [None]):
> > if singleton_provider.__defaults__[0][0] == None:
> > singleton_provider.__defaults__[0][0] = SomeClass()
> > return singleton_provider.__defaults__[0][0]
> >
>
> Why not simply:
> def get_singleton(x = SomeClass()):
> return x
> Or even:
> singleton = SomeClass()
> ? Neither of the above provides anything above the last one, except
> for late creation.
> ChrisA
Hi Chris
Does it make sense to use former as template to make
singleton from any class as below, so instead of addressing
your second proposal using module name we can directly call
this one supplying class candidate for singleness as argument
to function?
class whatever():
def __init__(self):
self.one = 1
self.zero = 0
def singleton_provider(someclass, x = [None]):
if singleton_provider.__defaults__[0][0] == None:
singleton_provider.__defaults__[0][0] = someclass()
return singleton_provider.__defaults__[0][0]
print(id(singleton_provider(whatever)))
Thanks
Asaf
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