[jQuery] jquery.calculation modification

[introvert]

Hello,

I need some help on jquery.calculation plugin modification (I want to
change it so that it would also read the attributes of elements if a
string is passed as an attribute name).

I want to change the .calc function so that I could optinally pass a
string with each jquery object which are passed as an array of
objects:

("[id^=total_item]").calc(
        "qty * price",
        // define the variables used in the equation, these can be a jQuery
object
        {
                qty: $("input[name^=qty_item_]"),
                price: $("[id^=price_item_]")
        },
        function (s){
                return "$" + s.toFixed(2);
        },
        function ($this){
        }
);

I want to be able to specify a string for each row in an array (qty,
price) (as an array).

Maybe something like:
                qty: $("input[name^=qty_item_]")["some_str"],
                price: $("[id^=price_item_]")


I'm unsure how should I change the syntax and retrive the value inside
the calc function (the second argument is called vars):

for( var k in vars ){
        // replace the keys in the expression
        expr = expr.replace( (new RegExp("(" + k + ")", "g")), "_.$1");
        if( !!vars[k] && !!vars[k].jquery ){
                parsedVars[k] = vars[k].parseNumber();
        } else {
                parsedVars[k] = vars[k];
        }
}

Many thanks in advance!