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```{index} single: Test2::Util::ExternalMeta
```

# Test2::Util::ExternalMeta

Allow third party tools to safely attach meta-data
to your instances.

## DESCRIPTION

This package lets you define a clear, and consistent way to allow third party
tools to attach meta-data to your instances. If your object consumes this
package, and imports its methods, then third party meta-data has a safe place
to live.

## SYNOPSIS

```perl
package My::Object;
use strict;
use warnings;

use Test2::Util::ExternalMeta qw/meta get_meta set_meta delete_meta/;

...
```

Now to use it:

```perl
my $inst = My::Object->new;

$inst->set_meta(foo => 'bar');
my $val = $inst->get_meta('foo');
```

## WHERE IS THE DATA STORED?

This package assumes your instances are blessed hashrefs, it will not work if
that is not true. It will store all meta-data in the `_meta` key on your
objects hash. If your object makes use of the `_meta` key in its underlying
hash, then there is a conflict and you cannot use this package.

## EXPORTS

- $val = $obj->meta($key)
- $val = $obj->meta($key, $default)

    This will get the value for a specified meta `$key`. Normally this will return
    `undef` when there is no value for the `$key`, however you can specify a
    `$default` value to set when no value is already set.

- $val = $obj->get\_meta($key)

    This will get the value for a specified meta `$key`. This does not have the
    `$default` overhead that `meta()` does.

- $val = $obj->delete\_meta($key)

    This will remove the value of a specified meta `$key`. The old `$val` will be
    returned.

- $obj->set\_meta($key, $val)

    Set the value of a specified meta `$key`.

## META-KEY RESTRICTIONS

Meta keys must be defined, and must be true when used as a boolean. Keys may
not be references. You are free to stringify a reference `"$ref"` for use as a
key, but this package will not stringify it for you.

## SOURCE

The source code repository for Test2 can be found at
[https://github.com/Test-More/test-more/](https://github.com/Test-More/test-more/).

## MAINTAINERS

- Chad Granum <exodist@cpan.org>

## AUTHORS

- Chad Granum <exodist@cpan.org>

## COPYRIGHT

Copyright Chad Granum <exodist@cpan.org>.

This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.

See [https://dev.perl.org/licenses/](https://dev.perl.org/licenses/)