On Saturday, August 11, 2001, at 11:25 AM, alan.gauld@[...].com wrote:

[snip]

>  Thus
> 
>  cook = Cook()
>  pantry = Pantry()
>  cook.makeMeal()
> 
>  And the makeMeal method might look like this:
> 
>  class Cook:
>     def makeMeal(meal)
>        ingredients = pantry.gather()
>        for item in ingredients
>            item.sift()
>        return meal.bake(ingredients)

Don't you lose polymorphism by hard-coding a call to a specific 
instance's method? Wouldn't it be more consistent with OO design to 
allow "makeMeal" to call the "gather" method of any object that 
implements it?  For example:

class Cook:
	def makeMeal(self, meal, supplier):
		ingredients = supplier.gather(meal)
		. . .

cook1 = Cook()
source1 = Pantry()
lunch = cook1.makeMeal("tuna fish sandwich", source1)

cook2 = Cook()
source2 = CheeseShop()
snack = cook2.makeMeal("camembert and crackers", source2)

for-some-reason-i'm-feeling-a-might-peckish'ly yours, sburrious

_______________________________________________
Tutor maillist  -  Tutor@[...].org
http://mail.python.org/mailman/listinfo/tutor