[cgiapp] Re: Q on Data::FormValidator filters used in my C::A

[Mark Stosberg <suppressed>]

On 2005-08-30, Kleindenst, Fred <suppressed> wrote:
>
> OK so far, I want to use the mentioned anonymous sub.  I'm not sure on
> the syntax.

Here's one way to check it:

    sub foo {42};
    use Data::Dumper;
    print Dumper ( \foo(), \&foo );

You'll see you get different results. The first syntax is reference
to the output of a subroutine. The second syntax is a reference to 
the subroutine itself. That's what you want. 

> (How do I specify the input to pass in?) 

You don't and you can't. When you declare a DFV profile, you don't know the
values will be, because the validation step hasn't happened yet. 

That's OK because you don't need to /execute/ the subroutines in your profile,
you just need to /declare/ them.

DFV will pass in arguments and execute the subroutine as part of the
processing.

The concept was used widely in DFV 4.0 to clean up the API. For more
in-depth learning on this topic, I recommend the book Higher Order Perl,
which is all about subroutines that have other subroutines as inputs or
outputs. 

    Mark

-- 
http://mark.stosberg.com/ 


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