There are several ways to do this, depending on how much validation you want to add. A lightweight method without any validation is to add a
BUILDARGS routine to your class (see
Moose::Manual::Construction):
sub BUILDARGS {
my $class = shift;
my %args = ref $_[0] ? %{$_[0]} : @_;
$args{code} = uc $args{code} if exists $args{code};
return \%args;
}
A more idiomatic method is to add a Moose type for the currency code, check for its validity, and then allow lowercase input by converting it under the hood by Moose coercion. Here's a complete example:
package UpperCaseDemo;
use Moose;
use Moose::Util::TypeConstraints;
with 'MooseX::Getopt';
subtype 'CurrencyCode'
=> as 'Str'
=> where { /^[A-Z]{3}$/ }
=> message { 'Currency codes should be three characters' },
;
coerce 'CurrencyCode'
=> from 'Str'
=> via { uc }
;
has 'code' => (
is => 'ro', isa => 'CurrencyCode',
coerce => 1,
);
1;
# -----------
# Usage: lookup --code abc or lookup --code ABC
#
package main;
my $cc = UpperCaseDemo->new_with_options();
print "code is ", $cc->code // 'not set', "\n";
BTW: I don't think that triggers are supposed to be allowed to change readonly attributes. Where did you read that?
