[Tutor] Passing perimeters in dictionary values?

[Kent Johnson]

On Tue, Feb 24, 2009 at 2:03 PM, nathan virgil <sdragon1984 at gmail.com> wrote:
> I'm experimenting with OOP using the Critter Caretaker script from Python
> Programming for the Absolute Beginner as my basis. I've noticed that a
> dictionary/function combo is a great way to handle menus, and so I've
> adapted the menu to read as:
>
>
> selection = raw_input("Choice: ")
> choices = {"0":quit, "1":crit.talk, "2":crit.eat, "3":crit.play}
> choice = choices[selection]
> choice()
>
> so that I can call methods from a dictionary, instead of having an
> excruciatingly long if structure. Unfortunately, the problem I'm running
> into with this is that I can't pass any perimeters through the dictionary. I
> can't figure out how, for example, I could have an option that calls
> crit.eat(2) and another that calls crit.eat(4). The only thing I can think
> of is going back to the if structure, but my instinct tells me that this is
> a Bad Idea. What can I do?

You can define a function that does what you want:
def eat2():
  crit.eat(2)

Then put eat2 in your dictionary:
choices = { '2': eat2, ...}

Alternately you can use lambda expressions to do the same thing
without an explicit def:
choices = { '2': lambda: crit.eat(2), ... }

Kent