libseed-list named arguments

[Jonatan Liljedahl <lijon kymatica com>]

Ever wished JS had named arguments? Here's one way to do it:

Function.prototype.named_call = function(self,namedargs) {
    var a = Array.prototype.slice.call(arguments,2);
    var names = this.argumentNames();
    for (var i=0;i<names.length;i++) {
        var x = namedargs[names[i]];
        if(x) a[i] = x
    }
    return this.apply(self,a);
}
Function.prototype.argumentNames = function() {
    if(this.__parmNames) return this.__parmNames;
    var names = 
this.toString().match(/^[\s\(]*function[^(]*\(([^)]*)\)/)[1]
      .replace(/\/\/.*?[\r\n]|\/\*(?:.|[\r\n])*?\*\//g, '')
      .replace(/\s+/g, '').split(',');
    return this.__parmNames = (names.length == 1 && !names[0] ? [] : 
names);
}

Then you can do stuff like this:

f = function(a,b,c) { ... }
f.named_call(this, {a:42,b:'foo'});

It does add some performance cost of course, any ideas how to speed it up?

PS. I use this in AlgoScript so that f(a=>42,b=>'foo') automatically 
turns into a named_call(), but only if there where any named args in the 
call.

/Jonatan