Le Wednesday 03 September 2008 17:40:43 mk, vous avez écrit :
> > Note that if one property can really be computed from another, this kind
> > of thing could be considered as bad design (except if the computation is
> > heavy).
>
> Hmm, why? Is the line of thinking smth like: because the variables
> should be kept to minimum and they should be calculated at the moment
> they are needed?
Because you have to make extra effort to keep the logical relation between
value and square. self._square is not really needed, and what is not needed
is just extra hassle.
Doesn't it clear that your code is more hard to maintain than the
alternative :
class Squared(object):
def __init__(self, val):
self._val=val
def fgetvalue(self):
return self._val
def fsetvalue(self, val):
self._val=val
value = property(fgetvalue, fsetvalue)
def fgetsquare(self):
return self.value ** 2
def fsetsquare(self,s):
self.value = math.sqrt(s)
square = property(fgetsquare, fsetsquare)
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Maric Michaud
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