[Tutor] Object Oriented References? and a couple of question s <--LONG

[Steven Burr]

On Saturday, August 11, 2001, at 11:25 AM, alan.gauld@bt.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