How does __setitem__() work?

[Alex]

If you do this:

class Test:
    
    def __setattr__(self, attribute, value):
        print 'setting', attribute, 'to', value
        self.__dict__[attribute] = value
    
    def __setitem__(self, index, value):
        print 'setting index', index, 'to', value
        ## THE_BLANK

t = Test(); t.list = [1,2,3]
t[0] = 7

The result is 

setting list to [1, 2, 3]
setting index 0 to 7

You have to assign to an 'item' of the instance itself for the
__setitem__ method to be called.  Assigning to 'items' of members won't
involve the instance itself.

Alex.