MooX::Attribute::ENV - Allow Moo attributes to get their values from %ENV

OS	Build status
Linux

package MyMod;
use Moo;
use MooX::Attribute::ENV;
# look for $ENV{attr_val} and $ENV{ATTR_VAL}
has attr => (
  is => 'ro',
  env_key => 'attr_val',
);
# look for $ENV{attr_val} and $ENV{next_val}, in that order
has some => (
  is => 'ro',
  env_key => [ 'attr_val', 'next_val' ],
);
# looks for $ENV{otherattr} and $ENV{OTHERATTR}, then any default
has otherattr => (
  is => 'ro',
  env => 1,
  default => 7,
);
# looks for $ENV{xxx_prefixattr} and $ENV{XXX_PREFIXATTR}
has prefixattr => (
  is => 'ro',
  env_prefix => 'xxx',
);
# looks for $ENV{MyMod_packageattr} and $ENV{MYMOD_PACKAGEATTR}
has packageattr => (
  is => 'ro',
  env_package_prefix => 1,
);

$ perl -MMyMod -E 'say MyMod->new(attr => 2)->attr'
# 2
$ ATTR_VAL=3 perl -MMyMod -E 'say MyMod->new->attr'
# 3
$ OTHERATTR=4 perl -MMyMod -E 'say MyMod->new->otherattr'
# 4

This is a Moo extension. It allows other attributes for "has" in Moo. If any of these are given, then "BUILDARGS" in Moo is wrapped so that values for object attributes can, if not supplied in the normal construction process, come from the environment.

The environment will be searched for either the given case, or upper case, version of the names discussed below.

When a prefix is mentioned, it will be prepended to the mentioned name, with a _ in between.

Boolean. If true, the name is the attribute, no prefix.

String. If true, the name is the given value, no prefix.

or

ArrayRef. A list of names that will be checked in given order.

String. The prefix is the given value.

Boolean. If true, use as the prefix the current package-name, with :: replaced with _.

Ed J, porting John Napiorkowski's excellent MooseX::Attribute::ENV.

The same terms as Perl itself.