On Oct 15, 7:34 am, Mr.SpOOn <[EMAIL PROTECTED]> wrote: > Hi, > in a project I'm overloading a lot of comparison and arithmetic > operators to make them working with more complex classes that I > defined. > > Sometimes I need a different behavior of the operator depending on the > argument. For example, if I compare a object with an int, I get a > result, but if I compare the same object with a string, or another > object, I get another result. > > What is the best way to do this? Shall I use a lot of "if...elif" > statements inside the overloaded operator? Or is there a more pythonic > and dynamic way?
Multimethods do the thing you're looking for. Google: 'python multimethods' gives: http://www.artima.com/weblogs/viewpost.jsp?thread=101605 by van Rossum. Some examples: from mm import multimethod @multimethod(int, int) def foo(a, b): ...code for two ints... @multimethod(float, float): def foo(a, b): ...code for two floats.. It is especially good if you're using inheritance. You could also collect the names of the types, and call a function by name: (untested) fname= a.__class__.__name__+ '_'+ b.__class__.__name__ or fname= re.sub( '[^a-Za-z0-9]+', '', str( type( a ) ) ) + same type( b ) ffunc= getattr( namespace, fname ) or build a dictionary. (untested) f= {} f[ int, int ]= compA f[ int, str ]= compB ... ffunc= f[ type( a ), type( b ) ] What's your favorite? -- http://mail.python.org/mailman/listinfo/python-list
