Question

I’m trying to change function arguments in javascript.

f = function(){
    console.log(a,b,c);
};

SetArgumentList( f, ["a", "b", "c"] );

f(1,2,3);
// should print "1 2 3"

// [edit]
// alternatively SetArgumentList could also work like
f = SetArgumentList( f, ["a", "b", "c"] );

Is there some solid way of doing this?

---

Where do I need it?… basically I’m trying to add type checked functions:

Object.prototype.method = function( name, typedef, func ){ ... }

function Thing(){};

Thing.method("log", 
    { arr: Array, str: String }, 
    function(){
        console.log(arr, str);
    });

t = new Thing();
t.log([1,2,3], "ok");
t.log("err", "ok"); // <-- causes an exception

// I know I can do this way
Thing.method("log", 
    [Array, String], 
    function(arr, str){
        console.log(arr, str);
    });
// but that's harder to read

NOTE! I know how to do type checking, but not the new function construction.

Answer 1

Tested in IE7,8,9, opera, chrome, firefox and safari. Uses evil in the background, but
I cannot see any other way if you must rename arguments.

(function(){
var decompileRE = /function\s*\([\s\S]*?\)\s*\{([\s\S]*)/,
    lastBrace = /\}[^}]*$/;

    window.SetArgumentList = function( fn, argNames ) {
    var match

        if( !( match = fn.toString().match( decompileRE ) ) ) {
        return fn;
        }

    argNames.push( match[1].replace( lastBrace, "" ) );


    return Function.apply( null, argNames );
    };

})()

f = function(){
    console.log(a,b,c);
};

f = SetArgumentList( f, ["a","b","c"] );

console.log(f);

Logs this in all browsers mentioned above:

function anonymous(a,b,c) {

    console.log(a,b,c);

}