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lib/Acme/Sub/Parms.pod  view on Meta::CPAN

the $arguments_anon_hash is a 'live' reference to a hash containing
all of the arguments being processed by BindParms block.

Because it is a 'live' hash reference, alterations to the hash will be
reflected in subsequent binding lines and in the final values bound.
This is a powerful, but simultaneously very dangerous feature. Use
this ability with caution. 

The callback must return either a true or a false value (not the
literal words 'true' or 'false' but something that evaluates to
a true or false logical value) and a string with an error message
(if a false value was returned.)

Callback function example:

 # Checking if the field value is an integer
 sub _is_integer {
    my ($field_name, $field_value, $args_hash) = @_;
    unless (defined ($field_value))            { return (0, 'Not defined');    }
    unless (int($field_value) eq $field_value) { return (0, 'Not an integer'); }
    return 1;