I've got a module where I precompile regexes for speed/later use. But I can't decide what's best practice in terms of how I handle these module constants. 
package Foo::Bar;

use Regexp::Assemble;

our $VERSION = '0.01';

sub new {
    my $class = shift;
    my $self = bless({@_}, $class);

    ## precompile regexes
    $self->{regex} = Regexp::Assemble->new->add( 'some-stuff' )->re;

    return $self;
}

sub function {
    my $self;

...

    $var =~ $regex;
}

[download]
vs. 
package Foo::Bar;

use Regexp::Assemble;

our $VERSION = '0.01';
our $regex = Regexp::Assemble->new->add( 'some-stuff' )->re;

sub function {
...
    $var =~ $regex;
}

[download]

I don't hesitate to declare module wide constants within the on-load/BEGIN part of a module, but it somehow feels wrong when these constants require some computation on-load, like here, precompiling regexes.

I would favour the the latter version. Doing a clean OO-style init and having the $obj var around is a bit cumbersome for the simple module I'm working on.
Arg, noticed that? I used the word "clean" to describe having these 'constants' in $self...

So please Monks, give me some advice. Is it just a matter of style, or design priciples, or are there actual problematic things to consider when my constants do some computing on-load?

(One difference I can think of is that this computing introduces an overhead and with my decision I decide for the module user where the precompilation overhead ends up:
  "fast load" + "mandatory new(), slowed" + "fast method" -- OO-style
  vs.
  "slower load" + "no mandatory new()" + "fast method". -- on-load style

Anything except that?

In reply to Modules: computing a constant, "on load" or in new()? by isync

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