• require or do a dedicated file with constants only

There are good reasons for NOT storing configuration data as Perl code:

• Re^2: conf file in Perl syntax
• Re: Accessing variables in an external hash without eval
• Re^4: The safety of string eval and block eval.
• Re^2: Storing state of execution
• Re: What's the right way to include a config file as a .pm bareword?
• Re^4: how to read conf file in perl script

Alexander

Sure. And the world is a bad place. Did you ever avoid to load a module because it can execute arbitrary code?

I would prefer command-line parameters but if the OP insists loading constants from a module isn't so bad IMHO:

package MyConf {

    use constant NOSE => q(cuke);
    use feature qw(say);
    say __PACKAGE__;
    1;
}
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#!/usr/bin/env perl                                                   

use strict;
use warnings;
use feature qw(say);
use lib q(.);
use MyConf;

say qq(My nose isa @{[MyConf::NOSE]}!);

__END__
[download]

Best regards, Karl

«The Crux of the Biscuit is the Apostrophe»

perl -MCrypt::CBC -E 'say Crypt::CBC->new(-key=>'kgb',-cipher=>"Blowfish")->decrypt_hex($ENV{KARL});'Help