Question

I have a class MyClass, which contains two member variables foo and bar:

class MyClass:
    def __init__(self, foo, bar):
        self.foo = foo
        self.bar = bar

I have two instances of this class, each of which has identical values for foo and bar:

x = MyClass('foo', 'bar')
y = MyClass('foo', 'bar')

However, when I compare them for equality, Python returns False:

>>> x == y
False

How can I make python consider these two objects equal?

Answer 1

you have to tell python how exactly you want equality be defined.
do so by defining a special method __eq__ like this:

def __eq__(self, other):
    return self.attrfoo == other.attrfoo # change that to your needs

the __cmp__(self, other) is the “old” style to compare instances of classes, and only used when there is no rich comparison special method found. read up on them here: http://docs.python.org/release/2.7/reference/datamodel.html#specialnames