How do I define default attribute property values in Moose?

Question

As the title suggests, I'd like to be able to do something like this in my class:

use MooseX::Declare;

class MyClass {
    default_attribute_propeties(
        is       => 'ro',
        lazy     => 1,
        required => 1,
    );

    has [qw( some standard props )] => ();

    has 'override_default_props' => (
        is       => 'rw',
        required => 0,
        ...
    );

    ...
}

That is, define some default property values that will apply to all attribute definitions unless overridden.

Answer 1

It sounds like you want to write some custom attribute declarations, that provide some default options. This is covered in Moose::Cookbook::Extending::Recipe1, e.g.:

package MyApp::Mooseish;

use Moose ();
use Moose::Exporter;

Moose::Exporter->setup_import_methods(
    install     => [ qw(import unimport init_meta) ],
    with_meta   => ['has_table'],
    also        => 'Moose',
);

sub has_table
{
    my ($meta, $name, %config) = @_;

    $meta->add_attribute(
        $name,

        # overridable defaults.
        is => 'rw',
        isa => 'Value', # any defined non-reference; hopefully the caller
                        # passed their own type, which will override
                        # this one.
        # other options you may wish to supply, or calculate based on
        # other arguments passed to this function...

        %config,
    );
}

And then in your class:

package MyApp::SomeObject;

use MyApp::Moosish;

has_table => (
    # any normal 'has' options;
    # will override the defaults.
);

# remaining class definition as normal.