ActiveSupport::Concern small question

Rails
#1

Hello all.

In this example, as i understand that included block is running when
Exclaimable module is included in Person and after a Person class
methods
are ‘initialized’

require ‘active_support/concern’

module Exclaimable
extend ActiveSupport::Concern
included do
self.new.hello
end
end

class Person
include Exclaimable
def hello
puts ‘person hello’
end
end

Output: Exception: NoMethodError: undefined method `hello’ for
#Person:0x00000103cbdcd0

But i see that, Person class doesn’t have hello method, why ? Please,
help
!

So, i can’t understand - what diifference between

included do
self.new.hello
end

and class method:

self.included(base)
base.new.hello
end

Both code get same error ( see above )

#2

On Friday, 10 October 2014 09:08:29 UTC-4, rusik wrote:

Hello all.

In this example, as i understand that included block is running when
Exclaimable module is included in Person and after a Person class
methods are ‘initialized’

No. See below for additional information, but if include Exclaimable
is
the first thing in a class definition, only methods defined on the
declaring class’s superclass (Object, in the case of Person) will be
available.

end

Output: Exception: NoMethodError: undefined method `hello’ for
#Person:0x00000103cbdcd0

But i see that, Person class doesn’t have hello method, why ? Please,
help !

The stuff between class Person and end is just code. The hello
method
isn’t available yet because it hasn’t been DEFINED yet when include Exclaimable executes.

self.included(base)
base.new.hello
end

Both code get same error ( see above )

self.included is Ruby’s built-in hook. (
http://www.ruby-doc.org/core-2.1.3/Module.html#method-i-included ) It
gets
called when the module that declares it is included in another module or
class.

ActiveSupport::Concern adds the included do idiom, to make
situations
where one module depends on another more straightforward. See the last
section of the docs for more:

http://api.rubyonrails.org/classes/ActiveSupport/Concern.html

–Matt J.