BartC wrote: > So 'range' is just a class like any other. And that a class is something > you can blithely copy from one variable to another. And whenever you see > 'range' anywhere, you can't always be certain that someone hasn't done: > > range = 42 > > at some point.
True. I read an explanation here that IMHO pretty well explains what's going on: The "range" above is a label, attached with a piece of string to an object. The object in this case is the integer 42. The same object can have multiple labels attached to it, so "foo = bar" will just create a new label "foo" and attach it to the object that the label "bar" is already attached to. Note that I said object, which includes class instances like the int 42 above, but also the classes themselves, functions (or bound functions[1]) and modules (I hope I didn't miss any). > That explains a lot about the difficulties of implementing Python > efficiently. Yes, "range" is not a keyword or something intrinsic to the interpreter. It is just a name that is looked up whenever it is encountered, and that costs time. However, you also get some nice flexibility at that cost. Cheers! Uli [1] bound function = class function where the instance parameter is bound. Example: x = [] a = x.append a(42) # calls x.append(42) -- Sator Laser GmbH Geschäftsführer: Thorsten Föcking, Amtsgericht Hamburg HR B62 932 -- http://mail.python.org/mailman/listinfo/python-list
