Eliminate eval'ish Function constructor usage

[brettz9]

Would you be open to a PR to get rid of the Function usage? This is discouraged practice and can be implemented by other means. Thanks!

[AlexeyGrishin]

Thank you for your feedback.

Actually Function is used to precompile code which iterates over schema/object to get performance. I saw that a lot of libraries like template engines (handlebars, jade) or JSON schema validators use Function for the same reason. So I do not think it is really evil here.

First version did not use it, but performance was terrible. How would you suggest to achieve the similar performance without code generation?

[brettz9]

Do you mean that code generation using such as the following example of a closure pattern has too high of performance problems? I'd actually think that eval() would be slower:

function buildForCallback (i, end, inc, cb) {
    return function () {
        for (; i < end; i += inc) {
            cb();
        }
    };
}