MooseX:...yRequire(3)

hiii bestie 💖 welcome to the MooseX::LazyRequire(3) manual page — yes, the one from User Contributed Perl Documentation. this is the whole “required attributes but make it delayed” situation, and it’s lowkey iconic.

💅 NAME 💅

MooseX::LazyRequire — required attributes that don’t fail until somebody actually tries to use them. it’s giving “you had one job, and the job is to complain later.” 💀

✨ VERSION ✨

version 0.11 — periodt.

🎀 SYNOPSIS 🎀

okay so here’s the whole vibe, bestie:

package Foo;

use Moose;
use MooseX::LazyRequire;

has foo => (
    is            => 'ro',
    lazy_required => 1,
);

has bar => (
    is      => 'ro',
    builder => '_build_bar',
);

sub _build_bar { shift->foo }

Foo->new(foo => 42); # succeeds, foo and bar will be 42
Foo->new(bar => 42); # succeeds, bar will be 42
Foo->new;            # fails, neither foo nor bare were given

like… the comments are literally the plot. Foo->new(foo => 42) succeeds, Foo->new(bar => 42) succeeds, and Foo->new fails because neither foo nor bare were given. slay. 🦋

🌈 DESCRIPTION 🌈

this module adds a lazy_required option to Moose attribute declarations. that’s the whole magic trick, and it ate. ✨

the reader methods for all attributes with that option will throw an exception unless a value for the attributes was provided earlier by a constructor parameter or through a writer method. so it’s not “required at construction time” required — it’s “required by the time you actually try to read it” required. very main character energy. 👑

🦋 CAVEATS 🦋

caveat zone, bestie — pay attention, this part is important 🫶

prior to Moose 1.9900, roles didn’t have an attribute metaclass, so this module can’t easily apply its magic to attributes defined in roles. if you want to use lazy_required in role attributes, you’ll have to apply the attribute trait yourself:

has foo => (
    traits        => ['LazyRequire'],
    is            => 'ro',
    lazy_required => 1,
);

with Moose 1.9900, you can use this module in roles just the same way you can in classes. so if you’re on the newer Moose, you’re chilling. 💅

👑 AUTHORS 👑

• Florian Ragwitz <rafl@debian.org>
• Dave Rolsky <autarch@urth.org>

💖 COPYRIGHT AND LICENSE 💖

this software is copyright (c) 2009 by Florian Ragwitz.

this is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

🫶 CONTRIBUTORS 🫶

• Karen Etheridge <ether@cpan.org>
• David Precious <davidp@preshweb.co.uk>
• Jesse Luehrs <doy@tozt.net>

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and that’s the page, bestie 🧚 source/version/date sign-off: perl v5.42.0, 2015-01-08, manual MooseX:...yRequire(3). periodt 💜