On Fri, Jun 1, 2012 at 9:39 AM, Josh Benner <sjben...@gmail.com> wrote: > > Is there a good way to trace what's going on under the hood wrt operator > overloading? > > I am trying to understand what is happening in the code and output listed > below. > > Why doesn't __getitem__ in mylist return the same result as the builtin list > object?
Because your class is old-style rather than new-style since it doesn't subclass the `object` class. See http://docs.python.org/reference/datamodel.html#newstyle . Thus, you're getting the weird, more complicated, old-style semantics for the operator in question. <snip> > ____code___________________________________________________ > > class mylist(): <snip> The fix is jus to subclass `object`: class mylist(object): Or use Python version 3.x, where all classes are new-style, and old-style classes no longer exist. Note that classes need only indirectly subclass `object` to be new-style; so, if you have an actual class hierarchy, only the root of your hierarchy needs to subclass `object` (this is also why subclassing built-in types like `list` or `tuple` also results in new-style classes: the built-in types themselves are `object` subclasses). Also, as a general point of coding style, one normally omits the parentheses after the class name if one isn't subclassing anything. Cheers, Chris -- http://rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
