Puzzling OO design problem

[George Sakkis]

"Bengt Richter" <bokr at oz.net> wrote in message
news:425919b6.16894062 at news.oz.net...
>
> See if this does what you want:
>
> [snipped]
>

Yes, that's pretty much what I had in mind. I particularly liked the
idea of mirroring automagically the nested class inheritance in each
version. So I tried to refine this recipe a little and I pushed down
the boilerplate code from 3 lines to one word; laziness is a virtue :-)


Below is the test only; I posted the main module to
http://rafb.net/paste/results/Hweu3t19.html to avoid messing up the
indentation.

Cheers,
George

#=================================================
# test.py
from namespace import Namespace

class Era(object):
    def __init__(self):
        self.lumberjack = self.GameUnit()
        self.warrior = self.CombatUnit()
        self.shooter = self.RangedUnit()

class MedievalAge(Era):
    __metaclass__ = Namespace()
    class GameUnit(object):
        def move(self): return "MedievalAge.GameUnit.move()"
    class CombatUnit(GameUnit):
        def fight(self): return "MedievalAge.CombatUnit.fight()"
    class RangedUnit(CombatUnit):
        def aim(self): return "MedievalAge.RangedUnit.aim()"

class ColonialAge(Era):
    __metaclass__ = Namespace(MedievalAge)
    class CombatUnit:
        def fight(self): return "ColonialAge.CombatUnit.fight()"

class IndustrialAge(Era):
    __metaclass__ = Namespace(ColonialAge)
    class GameUnit:
        def move(self): return "IndustrialAge.GameUnit.move()"
    class RangedUnit:
        def aim(self): return "IndustrialAge.RangedUnit.aim()"


if __name__ == '__main__':
    for era in MedievalAge(), ColonialAge(), IndustrialAge():
        for player in era.lumberjack, era.warrior, era.shooter:
            for action in "move", "fight", "aim":
                try: result = getattr(player,action)()
                except AttributeError:
                    result = "N/A"
                print "%s:%s.%s:\t%s" % (type(era).__name__,
                                         type(player).__name__,
                                         action, result)