[Catalyst] HTML::Widget - optional constraints

[Michael Gray]

Hi

I'm playing with HTML::Widget.  I have a form with three fields for 
variants of the same info, only one of which is required.  So, the 'Any' 
constraint is useful.  However I want to do further checks on each of 
the fields, but only if the field actually contains a value.

As things stand, all constraints are applied regardless, so my empty 
fields get tested (and fail).

I can see a couple of options:

 1) Add a skip_if_empty() accessor to HTML::Widget::Constraint and 
    implement the logic in HTML::Widget::Constraint::process().  
    Optionally cope with an 'EmptyOr_' prefix in 
    HTML::Widget::constraint(), akin to 'Not_'.

 2) Write an HTML::Widget::Constraint::NotEmpty which takes a further 
    bunch of constraints to run on the listed elements only if they're 
    not empty, otherwise returning success.

(or (3) use the Callback constraint and roll my own, but...)

Any thoughts?  I'd be happy to try writing a patch.

-- 
Michael