> If you create a closure, using a memoization technique as per the original
> post, and then call type() on that closure, Python reports <type 'function'>.
Because it is. The closure is only sort of an extension to the locals()
available to that function. Not more, not less.
>
> If you use dir() on that closure-that-Python-calls-a-function, it tells
> you that there is an attribute "func_closure". But ordinary functions that
> aren't closures also have that attribute.
Because there is no difference between them - a function _can_ have a
closure, the same way a HttpRequest _can_ have POST-data or not. That
doesn't make it different.
You are of course right that one _could_ have implemented this with
different classes. But as it happens, it isn't.
>
> According to my tests, ordinary functions have None as the func_closure
> attribute, but I don't know if that will always be the case, or just the
> few examples I tested it. With a sample size of three, I have no
> confidence that I've found a bullet-proof test.
See this small testscript how to expose the closures content -- however
I'm not familiar with the mechanics the bind "some_variable" to the
cell-objects content. But actually I don't care...
def closure_test():
some_variable = {}
print "%x" % id(some_variable)
def get(x):
return some_variable[x]
def set(x,v):
some_variable[x] = v
return get, set
g, s = closure_test()
s(10, 20)
print g(10)
print s.func_closure[0]
Diez
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