[Tutor] Methods that return instances of their own class?
Andre Engels
andreengels at gmail.com
Thu Oct 15 17:31:36 CEST 2009
On Thu, Oct 15, 2009 at 5:14 PM, David Perlman <dperlman at wisc.edu> wrote:
> I'm trying to figure out how to define a class so that its instances have a
> method that return a different object of the same class.
>
> In particular, I'm trying to run a simple prisoner's dilemma game, and I
> want to make a "game" object that has a method which returns the "game"
> object with the payoffs reversed; that is, the payoff matrix from the other
> player's point of view. Basically a kind of transpose which is specific to
> this application.
>
> class Payoffs(list):
> def __init__(self, value=None):
> list.__init__(self)
> if value==None: # use a default prisoner's dilemma
> value=[[(3,3),(0,5)],
> [(5,0),(1,1)]]
> self.extend(value)
>
> def __repr__(self):
> l1="Your Choice: Cooperate Defect\n"
> l2="My choice: -------------------------\n"
> l3="Cooperate | (% 3d,% 3d) | (% 3d,% 3d) |\n" % (self[0][0][0],
> self[0][0][1], self[0][1][0], self[0][1][1])
> l4=" ----------------------- \n"
> l5="Defect | (% 3d,% 3d) | (% 3d,% 3d) |\n" % (self[1][0][0],
> self[1][0][1], self[1][1][0], self[1][1][1])
> l6=" -------------------------\n"
> return l1+l2+l3+l4+l5+l6
>
> def transpose(self):
>
> And that's where I'm at. How can I have the transpose method return another
> Payoffs object? Here's the beginning of it:
>
> def transpose(self):
> trans=[[(self[0][0][1],self[0][0][0]),
> (self[1][0][1],self[1][0][0])],
> [(self[0][1][1],self[0][1][0]),
> (self[1][1][1],self[1][1][0])]]
>
> But now "trans" is type list, not type Payoffs. I don't know how to get it
> into a Payoffs object so that the transpose will have my other new methods.
>
>
> Thanks very much. I searched for answers but I'm not sure what this would
> be called, which made it hard to find.
I may be thinking too simple, but isn't this just:
def transpose(self):
trans=[[(self[0][0][1],self[0][0][0]), (self[1][0][1],self[1][0][0])],
[(self[0][1][1],self[0][1][0]), (self[1][1][1],self[1][1][0])]]
return Payoffs(trans)
--
André Engels, andreengels at gmail.com
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