On Thu, 18 Mar 2010 00:19:40 -0700 Chris Rebert <pyideas@rebertia.com> wrote:
Are function attributes used *that* much?
I use them as a nice (& explicit, & clear) alternative to closures, esp. for func factories, eg: def powerN(n): def f(x): return x ** f.n f.n = n return f power3 = powerN(3) for i in range(1,10): print "%s:%s" %(i,power3(i)), # ==> 1:1 2:8 3:27 4:64 5:125 6:216 7:343 8:512 9:729 I find this conceptually much more satisfying than the following, since the parameter really is an attribute of the function (also, like a real upvalue, it can be explicetely updated). def powerN(n): def f(x,n=n): # ugly ;-) return x ** n return f (Let us use the opportunity that python funcs are real objects :-) A "parameterisable" generator factory: def powers(n, start=1, stop=None): def f(): while True: f.i += 1 if f.stop and f.i >= f.stop: raise StopIteration yield (f.i, f.i ** f.n) f.n = n f.i = start-1 f.stop = stop return f for (i,x) in powers(3, 1,10)(): print "%s:%s" %(i,x), # ==> 1:1 2:8 3:27 4:64 5:125 6:216 7:343 8:512 9:729 Denis ________________________________ vit e estrany spir.wikidot.com