Saager Mhatre <saager.mha...@gmail.com> writes:
[...] > Sigh! Implementing a reasonably important feature in an obscure manner > (that too, not completely, since even slots are accessible from > outside an object) is not in keeping with friendliness. I say this > feature is reasonably important since it is repeatedly brought up > every few months with little to no satisfactory responses most of > which is 'we are all adults here', which I am hard pressed to accept > as a generalization on account of all the atrocious code mentioned > above. __slots__ are not meant for data hiding. They're meant as a final "trick" to save memory when you have a large number of objects of the class you're interested in. If you define a __slots__ variable, you lose the class dictionary (since that consumes some amount of memory) but you get smaller objects. The gory details are here http://hg.python.org/cpython/file/9e322a8f80d9/Objects/typeobject.c but here's what it looks like. >>> class Foo(object): ... __slots__ = ['bar'] ... def __init__(self): ... self.bar = "Hello" ... def display(self): ... print self.bar ... >>> >>> x = Foo() >>> dir(x) # Uses slots. No __dict__ ['__class__', '__delattr__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__slots__', '__str__', '__subclasshook__', 'bar', 'display'] >>> >>> class Bar(object): ... def __init__(self): ... self.foo = "Hello" ... def display(self): ... print self.bar ... >>> y = Bar() >>> dir(y) # No slots so you have the __dict__ ['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'display', 'foo'] >>> >>> import sys >>> sys.getsizeof(x) 56 >>> sys.getsizeof(y) 64 As for the rest of your points, I agree with some. I'm generally gravitating towards statically typed languages of late so my comments will be vague anyway. -- Cordially, Noufal http://nibrahim.net.in _______________________________________________ BangPypers mailing list BangPypers@python.org https://mail.python.org/mailman/listinfo/bangpypers
