Class2

Easily create hierarchies of classes that support nested attributes, equality, and more.

Usage

Class2(
  :user => [
    :name, :age,
    :addresses => [
      :city, :state, :zip,
      :country => [ :name, :code ]
    ]
  ]
)

This creates 3 classes: User, Address, and Country with the following attribute accessors:

• User: name, age, addresses
• Address: city, state, zip, country
• Country: name, code

Each of these classes also contain several additional methods.

Example:

user = User.new(
  :name => "sshaw",
  :age  => 99,
  :addresses => [
    { :city => "LA",
      :country => { :code => "US" } },
    { :city => "NY Sizzle",
      :country => { :code => "US" } },
    { :city => "São José dos Campos",
      :country => { :code => "BR" } }
  ]
)

p user.name                  # "sshaw"
p user.addresses.size        # 3
p user.addresses.first.city  # "LA"

# Keys can be strings too
country = Country.new("name" => "America", "code" => "US")
address = Address.new(:city => "Da Bay", :state => "CA", :country => country)
user.addresses << address

p User.new(:name => "sshaw") == User.new(:name => "sshaw")  # true

Class2(:foo, :bar => :baz)
Foo.new
Bar.new(:baz => 123)

Namespaces

Class2 can use an exiting namespace or create a new one:

Class2(
  My::Namespace,
  :user => %i[name age]
)

My::Namespace::User.new(:name => "sshaw")

Class2(
  "New::Namespace",
  :user => %i[name age]
)

New::Namespace::User.new(:name => "sshaw")

Naming

Class2 uses String#classify to turn keys into class names. :foo will be Foo, :foo_bars will be FooBar. It also uses it to turn plural attribute names into singular classes. An :addresses attribute will result in a class named Address being created.

Plurality is determined by String#pluralize.

Methods

Classes created by Class2 will have:

• A constructor that accepts a nested attribute hash
• Attribute readers and writers
• #to_h
• #eql? and #==
• #hash

Custom Methods

Just open up the class and write them:

Class2(:user => :name)

class User
  def first_initial
    name[0] if name
  end
end

User.new(:name => "sshaw").first_initial

See Also

The Perl module that served as the inspiration: MooseX::NestedAttributesConstructor.

Author

Skye Shaw [sshaw AT gmail.com]

License

Released under the MIT License: www.opensource.org/licenses/MIT