package Foo {
  use Moo;
  has a => (is => "ro");
  has b => (is => "ro");
}

my $bar = Foo->new(a => 42);

# Print only 'a'
say $_ for keys %{ $bar }

# Print all attributes
say $_ for keys( %{
   'Moo'->_constructor_maker_for('Foo')->all_attribute_specs
});

Three weird tricks to make your object-oriented codemore encapsulated, more reusable, and more maintainable.

Aggregation is a very small JavaScript library for Node.js environments, providing just a single function, for use in ECMAScript 5/6 class inheritance based on mixins. It aggregates a base class and one or more mixin classes into an aggregate class, which then is usually subsequently used as the base class for another class.