Myco::Entity::Meta::Attribute

Myco::Entity::Meta::Attribute is a class that serves as a repository for metadata concerning a particular attribute of a Myco Entity class. In order to use it, you must add the attribute to the class within an entity class definition. It is important to note that this class is normally used only via Myco::Entity::Meta.

To add an attribute to the class, the constructor of ::Attribute should only be used via ::Meta's add_attribute() method. The code block for adding an attribute to the class is demonstrated below:

```Perl
my $md = Myco::Entity::Meta( name => __PACKAGE__ );
$md->add_attribute(
name => 'doneness',
type => 'int',
readonly => 0, # default is read/write
access_list => {
rw => ['admin'],
ro => [qw(average_joes junior_admins)]
},
tangram_options => { required => 1},
synopsis => "How you'd like your meat cooked",
syntax_msg => "correct format, please!",
values => [qw(0 1 2 3 4 5)],
value_labels => {
0 => 'rare',
1 => 'medium-rare',
2 => 'medium',
3 => 'medium-well',
4 => 'well',
5 => 'charred'
},
ui => {
widget => [ 'popup_menu' ],
label => 'Cook until...',
},
);
```

After the attribute has been added, usage of the code continues with standard post-setup usage. Given a Myco::Entity::Meta enabled entity object $obj, introspect to obtain metadata. Get reference to the array of ::Meta::Attribute objects for $obj's class via the get_attributes() method. Finally, look up the type of an attribute and use the stored accessor coderef to set the attribute value.

```Perl
# ...given a Myco::Entity::Meta enabled entity object $obj
my $metadata = $obj->introspect;
my $attributes = $metadata->get_attributes;

# Look up attribute's type
my $type = $attributes->{doneness}->get_type;

# Use of stored accessor coderef - set doneness = 3
$attributes->{doneness}->setval($obj, 3);
```

Overall, the Myco::Entity::Meta::Attribute class is an essential tool for working with Myco Entity classes.