Decorator for validation - inefficient?

[Arnaud Delobelle]

Bryan <bryanvick at gmail.com> writes:

> However, hoping to make client code cleaner and to avoid setter
> functions doing expensive db lookup validations, I do not validate
> during the setter, but instead defer it until the client explicitly
> asks for the validity of the business object.  So the essence of the
> client's request at that point is "what are the invalid values for the
> object", and an exception should only be raised if there was something
> stopping this request from being served.  Invalid business object
> field values do not stop the functionality of the invalid() method.

This is perfectly fine IMHO, in fact this is similar to how django does
form validation.  Each form has a property 'is_valid' and validation is
only triggered when form.is_valid is checked.  This doesn't raise
exceptions but makes the errors available to the form user.

-- 
Arnaud