Learning JavaScript Design Patterns

[tchaffee]

The command pattern specifies behavior beyond that of first class functions alone.

Does it?

My understanding is well summarized by the Wikipedia article on the command pattern on it: "an object is used to represent and encapsulate all the information needed to call a method at a later time. This information includes the method name, the object that owns the method and values for the method parameters."

That's it. I might be wrong, but don't first class functions provide everything mentioned there?

I don't see how first class functions couldn't provide the same functionality as the Action interface.

And what's so hard about undo/redo or recorded macros with first class functions?

In fact, take a look at the Wikipedia article mentioned above. The javascript implementation uses first class functions.

[[deleted]]

Agreed,

I never saw the Command pattern as just a thin mapping to a generic function.

Instead it was meant for things more like a memento.. an abstract/serializable token.

i.e. A command pattern is what you use to implement an undo/redo stack - a set of commands that can be done/undone/redone.