added explanation for prototype class variables

[wilzbach]

I stumbled across the problem of accidentally creating shared/static variables. I seems that I am not the first one - so I thought it might be a good idea to correct this cookbook ;-)
The recipe only works for primitive variables.

[michaelglass]

I think if you want to return the same value for a mutable object you should just

# use a getter
Foo.getButts = ->
  ['butts']

[wilzbach]

Actually my point was to show how to prevent sharing of non-primitive variables. If you follow the original recipe than the variables would behave like favoriteFoodShared, which is probably not the intended behavior.

[michaelglass]

but the section you're adding it to is the class variable section. And that functionality is already demonstrated here, I believe.

Happy to defer to a second opinion though.

[wilzbach]

I first wanted to add it there, but this is really about class variables. As I said before the original recipe explains how to have MAX_ZOOKEEPERS as a class variables.
However this won't work as expected with arrays etc.

It seems to be that at least it is not clear at the first glance what I want to show with this extension? I am open to any suggestions :-)

[michaelglass]

I think (maybe I'm reading it wrong) that it's demonstrating the difference between MAX_ANIMALS (a class variable) and MAX_ZOOKEEPERS (a prototyped variable)

[wilzbach]

Yep as far as I understand is MAX_ANIMALS shared between all instances (aka static) and MAX_ZOOKEEPERS is a instance variable.

Should I use MAX_ZOOKEEPERS instead of favoriteFoodShared?
All I wanted to show and warn is about the instance variable MAX_ZOOKEEPERS.

[wilzbach]

here is an example why I consider this tricky for beginners and the solution to instantiate the immutable variable in the constructor is needed. If you come from any other non-prototyped language you would expect tiger.mutable to be []

http://jsfiddle.net/3Fsbc/1/

[pbihler]

I think, you had some misunderstandings here due to misleading word use. The example provided by @greenify was about problems/pitfalls on instance variables. #121 solves the issue by extending the class-variables to a class-variables-and-instance-variables page (parallel to the *-methods page).

[wilzbach]

thanks @pbihler for #121. Exactly what I wanted to explain :)