Mastering extend and when you want class methods and instance methods for your class
Mastering extend and when you want class methods and instance methods for your class
I just realized something cool, which is the underlying of including same module for a class and share instance and class methods with that class.
So here is the trick
You have this simple module:
module TestModule
def test_name
'test_name'
end
end
And this class
class Test
def name
'Test'
end
end
Test.extend(TestModule)
irb(main):033> Test.test_name
=> "test_name"
irb(main):034> Test.new.name
=> "Test"
So that is why if you want to include both instance and class methods, with something like this
class Test
include TestModule
end
How would you include some as class methods, and the answer is by defining those methods in a module or subgroup within the module, and it would look like this
module TestModule
def instance_method
'instance method'
end
module TheClassMethods
def class_hello
'class_hello'
end
end
def self.included(base)
base.extend(TheClassMethods)
end
end
class Test
include TestModule
end
So now you can access both of them
Test.new.instance_method # instance method
Test.class_hello # class_hello
NOTE: remember that it is included in the past
def self.included(base)
base.extend(YouClassMethodsToShare)
end
And active_support/concern comparison
module M
def self.included(klass)
klass.extend ClassMethods
klass.class_eval do
scope :disabled, -> { where(disabled: true) }
end
end
def instance_method
'instance method'
end
module ClassMethods do
def class_method_one
'class method'
end
end
end
Vs
require 'active_support/concern'
module M
extend ActiveSupport::Concern
included do
scope :disabled, -> { where(disabled: true) }
def self.direct_class_method_here
..
end
end
class_methods do
def class_method_one
'class method one'
end
end
end
class YourClass
include M
end
