Crudely summarized, method resolution order is how Python decides whereto look for a method (or any other attribute) on a class that inheritsfrom several classes. Python actually has two; a simple one for oldstyle classes and a rather complicated one for new style classes.

(Technically, method resolution order applies even for singleinheritance classes, it's just that they have a very boring one.)

With the old style class:

class Foo(A, B, C):    pass

Python will look up

In Python, when you have a class that inherits from both a primary classand some mixin classes (for example, if you're using the SocketServerstuff ),it's conventional to declare your class's inheritance list with theprimary class first:

class Real(primary, mixin1, mixin2):    ....

However, an important safety tip: if your mixin class overrides methodsof the primary class, it has to be first . Failure to observe thissafety tip can cause head

If you can't find anything wrong, you haven't looked carefully enough.

The immediate corollary is also important:

If you can't find anything, the intruders are still there.

The leading cause for not finding anything wrong on a machine youknow is compromised is that you haven't detected the rootkit thatis hiding things from you.