Javascript named arguments

banquo.js

// so named because why the hell not?
function banquo(func) {
    var def = func.toString();
    
    // find the comma-delimeted list of parameters
    var params = def.match(/\(\s*(\w+(\s*,\s*\w+)*)\s*\)/)[1].split(',').map(function (p) {
        return p.trim();
    });
    
    // extract out just the function body
    var body = def.match(/\{((.|\n)+)\}/g)[0];
    body = body.substring(1, body.length - 1).trim();
    
    // this is recursive and would be better done iteratively, but I got bored
    function buildScript(ps) {
        var script = "{";
        for (var i = 0, l = ps.length; i < l; ++i) {
            var leftover = ps.slice();
            var p = leftover.splice(i, 1);
            
            if (i > 0) {
                script += ",";
            }
            
            script += p + ":function(" + p + "){";
            
            if (leftover.length > 0) {
                script += "return " + buildScript(leftover, body);
            }
            else {
                script += body;
            }
            script += "}";
        }
        script += "}";
        return script;
    }
    
    // at least a modicum of avoiding polluting the global scope
    var state = {obj: null};
    with (state) {
        eval("var obj = " + buildScript(params));
    }
    return state.obj;
}

var something = banquo(function (a, b, c, d) {
    console.log("A: ", a, ", B: ", b, ", C: ", c, ", D:", d);
});

something.a(1).b(2).c(3).d(4);
something.b(1).a(2).c(3).d(4);
something.a(1).c(2).b(3).d(4);
something.b(1).c(2).a(3).d(4);
something.c(1).a(2).b(3).d(4);
something.c(1).b(2).a(3).d(4);
something.a(1).b(2).d(3).c(4);
something.b(1).a(2).d(3).c(4);
something.a(1).c(2).d(3).b(4);
something.b(1).c(2).d(3).a(4);
something.c(1).a(2).d(3).b(4);
something.c(1).b(2).d(3).a(4);
something.a(1).d(2).b(3).c(4);
something.b(1).d(2).a(3).c(4);
something.a(1).d(2).c(3).b(4);
something.b(1).d(2).c(3).a(4);
something.c(1).d(2).a(3).b(4);
something.c(1).d(2).b(3).a(4);
something.d(1).a(2).b(3).c(4);
something.d(1).b(2).a(3).c(4);
something.d(1).a(2).c(3).b(4);
something.d(1).b(2).c(3).a(4);
something.d(1).c(2).a(3).b(4);
something.d(1).c(2).b(3).a(4);