On Thu, Oct 7, 2010 at 1:46 PM, Arnaud Delobelle <arno...@gmail.com> wrote: > kj <no.em...@please.post> writes: >> I want to implement a test t() that will return True if its two >> arguments are "completely" different. By this I mean that they >> don't share any "non-atomic" component. E.g., if >> >> a = [0, 1] >> b = [0, 1] >> c = [2, 3] >> d = [2, 3] >> >> A = (a, c, 0) >> B = (a, d, 1) >> C = (b, d, 0) >> >> The desired test t() would yield: >> >> t(A, B) -> False (A and B share the mutable component a) >> t(A, C) -> True (a =!= c, b =!= d, and 0 is not mutable) >> t(B, C) -> False (B and C share the mutable component d) >> >> (=!= is shorthand with "is not identical to".) >> >> It would facilitate the implementation of t() to have a simple test >> for mutability. Is there one? >> >> Thanks! >> >> ~kj > > I think defining mutability is subject to opinion, but here is a first > approximation. > > > def mutable(obj): > return obj.__hash__ is None or type(obj).__hash__ == object.__hash__
Corner case (I think): >>> a = object() >>> a.b = "c" Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: 'object' object has no attribute 'b' >>> mutable(a) True Cheers, Chris -- http://mail.python.org/mailman/listinfo/python-list
