[Catalyst] C:P::FormValidator::Simple and C:P:FillInForm

[Matt S Trout]

Nilson Santos Figueiredo Junior wrote:
> On 3/19/06, Bernhard Graf <catalyst at augensalat.de> wrote:
>>     if ( $c->isa('Catalyst::Plugin::FormValidator') ) {
>>         $c->fillform
>>             if $c->form->has_missing
>>     [...]
>> better
>>     if ( my $form = eval { $c->form } ) {
>>         $c->fillform
>>             if $form->has_missing
>>     [...]
> 
> eval()ing a method call just to see if it exists (if that's really
> what you meant) is ugly.
> Instead, you should use:
> 
> if ($c->can('form')) {
>   # code here
> }
> 
> If you're not sure whether $c is an object or not, you should use:
> 
> if (UNIVERSAL::can($c, 'form')) {
>   # code here
> }
> 
> If I've missed your point, please, disregard this message.

Never. Ever. Do this. Seriously.

http://search.cpan.org/~chromatic/UNIVERSAL-can-1.11/lib/UNIVERSAL/can.pm

"Some authors call methods in the UNIVERSAL class on potential invocants as 
functions, bypassing any possible overriding. This is wrong and you should not 
do it. Unfortunately, not everyone heeds this warning and their bad code can 
break your good code."

"Some people argue that you must call UNIVERSAL::can() as a function because 
you don't know if your proposed invocant is a valid invocant. That's silly. 
Use blessed() from Scalar::Util if you want to check that the potential 
invocant is an object"

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