liamgoodacre/multifn.js

Provides a method of combining multiple functions into one, and selecting one to execute based on the arguments passed to it.

MultiFn.js

MultiFn is a JavaScript utility which allows multiple implementations of a function based on different arguments. i.e. if you want different code to run if a function is called with an Array as opposed to an Object.

MultiFn.js was authored by Liam Goodacre using Coffee-Script.

Example

Check out the "[src/out]/test/" folders for example(s).

Syntax

CoffeeScript:

myFn = new MultiFn {
"Number Number": (_n1, _n2) -> myFn(_n1) + myFn(_n2)
"Number":  (_num) -> _num
"String": (_str) -> parseInt(_str, 10)
}

JavaScript:

var myFn = new MultiFn({
"Number Number": function (_n1, _n2) { return myFn(_n1) + myFn(_n2); },
"Number": function (_num) { return _num; },
"String": function (_str) { return parseInt(_str, 10); }
});

Defaults

MultiFn supports having a default implementation function, should none of the argument patterns match. The syntax is as follows:

CoffeeScript:

someFn = new MultiFn {
#...other functions...
"default": ->
# some default implementation
#...other functions...
}

JavaScript:

var someFn = new MultiFn({
//...other functions...
"default": function () {
// some default implementation
},
//...other functions...
});

Types

The string of types identifying the arguments for an implementation, is a space delimited sequence of regular expressions.

This means that instead of writing "Number", you could write "^Num", or event just "^N". It also means you can do things like "Element$" which would match "HTMLElement", "HTMLBodyElement", etc...

Another adavantage to this, is that ".*" will match any type of value:

"Number .* Number": (_num1, _anything, _num2) -> #...