Simplify implementations of UUID and URL validators.

[jenstroeger]

A few thoughts that I think would help improve flexibility of your code:

For the UUID validator

Instead of using a pattern matcher which doesn’t accept valid strings without hyphens (e.g. "1219ffcf45c78964b04a3290cf84183a"), why not just use Python’s own uuid module?

@validator
def uuid(value):
    try:
        return uuid.UUID(value) is not None
    except ValueError:
        return False

For the URL validator

Again an impressive funk of patterns 😉Why not use the rfc3987 module like so:

@validator
def url(value, public=False):
    try:
        result = rfc3987.parse(value)
        # Do `public` stuff here.
    except ValueError:
        return False

Note that this module also gives you a whole heap of regexes which you could use here instead of duplicating code.

And…

To simplify the above code, you’d also move the exception handling into the decorator:

def validator(func, *args, **kwargs):
    def wrapper(func, *args, **kwargs):
        try:
            value = func(*args, **kwargs)
            if not value:
                return ValidationFailure(
                    func, func_args_as_dict(func, args, kwargs)
                )
            return True
        except Exception:  # In the above two cases, ValueError.
           return ValidationFailure(func, func_args_as_dict(func, args, kwargs))
    return decorator(wrapper, func)

[kvesteri]

Thanks for suggestions!

1. PRs welcome for the UUID
2. rfc3987 package is licensed under GPLv3. Hence according to almight google I can't use that package here:
   "The MIT license is also compatible with many copyleft licenses, such as the GNU General Public License (GPL); MIT licensed software can be integrated into GPL software, but not the other way around."
3. I wouldn't use decorator like that. Catching generic Exception like that leads to all kinds of weird situations and might catch exceptions that the user wouldn't want to.