function fn(m, name, format, args){
            if(format && useF){
                args = args ? ',' + args : "";
                if(format.substr(0, 5) != "this."){
                    format = "fm." + format + '(';
                }else{
                    format = 'this.call("'+ format.substr(5) + '", ';
                    args = ", values";
                }
            }else{
                args= ''; format = "(values['" + name + "'] == undefined ? '' : ";
            }
            return "'"+ sep + format + "values['" + name + "']" + args + ")"+sep+"'";
        }
Compiles the template into an internal function, eliminating the RegEx overhead.
@return {Ext.Template} this
@hide repeat doc