---
name: "MooseX::LazyRequire"
section: "3pm"
platform: "linux"
package: "libmoosex-lazyrequire-perl"
version: "0.11-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/MooseX::LazyRequire"
---

# MooseX::LazyRequire(3pm)

Required attributes which fail only when trying to use them

## NAME

MooseX::LazyRequire - Required attributes which fail only when trying to use them

## VERSION

version 0.11

## SYNOPSIS

```
    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
```

## DESCRIPTION

This module adds a `"lazy_required"` option to Moose attribute declarations.

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.

## CAVEATS

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.

## 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\>