Calling Module Method into Another Module in Ruby

calling module method into another module in Ruby

You stumbled over the difference of include and extend.

• include makes the method in the included module available to instances of your class
• extend makes the methods in the included module available in the class

When defining a method with self.method_name and you access self within that method, self is bound to the current class.

check_expiry, however, is included and thus only available on the instance side.

To fix the problem either extend CardExpiry, or make check_expiry a class method.

Calling selected methods of a module from another module

That module A should be raising an ArgumentError unless it also has an extends ActiveSupport::Concern at the top. Without ActiveSupport::Concern, you'd be calling the Module#included instance method here:

included do
  ...
end

but that requires an argument.

If you say this:

module A
  extend ActiveSupport::Concern
  included do
    def self.some_func
    end
  end
end

then you'll get the included you're trying to use and the module A that you're expecting.

Also, module B doesn't include A so it has nowhere to get some_func from so this:

module B
  some_func
end

will give you a NoMethodError. If you include A:

module B
  include A
  some_func
end

then it will work.

How to access method defined in a module inside another module in Ruby?

Assuming you don't want class level methods, you can also include the module into a class, instantiate an object of that class and call whoa:

class C
   include A::B
end

c = C.new
c.whoa
# Whoa!

How to call a method from a module of an other ruby file

Require needs the absolute path to the file unless the file is located in one of Ruby's load paths. You can view the default load paths with puts $:. It is common to do one of the following to load a file:

Add the main file's directory to the load path and then use relative paths with require:

$: << File.dirname(__FILE__)
require "my_module"

Ruby 1.8 code that only loads a single file will often contain a one-liner like:

require File.expand_path("../my_module", __FILE__)

Ruby 1.9 added require_relative:

require_relative "my_module"

In the module you will need to define the methods as class methods, or use Module#module_function:

module MyModule
  def self.method1 ary
    ...
  end

  def method2
    ...
  end
  module_function :method2
end

a = [1,2,3,4]
MyModule.method1(a)

call a method of a module from another

Try to define check_mail in helpers/mail_check and then include MailCheck in user_controller.

Is it possible to call a Module function from inside a class that is also in that module

In order to invoke M::helper you need to define it as def self.helper; end
For the sake of comparison, take a look at helper and helper2 in the following modified snippet

module M
  class C < Struct.new(:param)
    include M     # include module to get helper2 mixed in
    def work
      M::helper(param)
      helper2(param)
    end
  end

  def self.helper(param)
    puts "hello #{param}"
  end

  def helper2(param)
    puts "Mixed in hello #{param}"
  end
end

c = M::C.new("world")
c.work

Including a module in other module

You can't.

When you include a mixin M into a class C, Ruby creates a new class ⟦M′⟧ whose method table points to the method table of the mixin M and whose superclass is the superclass of C, then makes this class the new superclass of C. This is repeated for every mixin that was mixed into M.

Note that this algorithm is run only once, when you mix M into C. Modules that get included later, will not get considered.

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