Stated differently, we're saying we can pass add(20, 45) and subtract(80, 10) as arguments to another method. With methods, one can organize their code into subroutines that can be easily invoked from other areas of their program. module Presenters::Validations module ClassMethods def validates_presence_of(*args).. end It basically making the B class a proxy for A, at least for one specified method (it receives a method call and forwards it to the actual target class). end end jack = Person.new There's the obvious way: jack.say You can send the method name: jack.send(:say) jack.public_send(:say) Maybe you want to grab the method, and then call it like a proc: jack.method(:say).call class Person def say 'hello!' Two method objects are equal if they are bound to the same object and refer to the same method definition and their owners are the same class or module. The new module could be included thus providing valid? The issue I'm having is that I want to give the user the choice of having the program restart. Other languages sometimes refer to this as a function.A method … I think it is closer to what you were hopping for originally. You know how to call a method on an object. Tim The class is instantiated, and then the methods … First, a class is defined with four methods, one of which is private, one is a class method and another takes a parameter. Step two: Another common approach is to define the class methods in a ClassMethods module inside the Presenters::Validations module. I was recently asked to think of all the ways you can call a method in Ruby. The code you have written involves mixin, you can see this as interface with implemented methods.When a class can inherit features from more than one parent class, the class is supposed to show multiple inheritance. Unlike in javascript, it appears I can't call a method ("function" in javascript terms) from within another method. module B include A end Including exposes all of A's methods into B.If you do not want this to happen, use Ruby's module_function: it makes a module's method accessible from the outside.You could put the module_function calls into A but it would remain unclear to people looking at B's code.. A cleaner way would be like this: new puts calculator. Ruby has three (at least) ways to call a method on an object. This code illustrates their use. Call method to generate arguments in ruby works in 1.8.7 but not 1.9.3 ruby-on-rails , ruby , ruby-1.9.3 Change required (in github notation): - myFunction(submitArgs()) + myFunction(*submitArgs) The reason that [I assume] myFunction is declared taking two arguments: def myFunction a1, a2 Hence the array must be splatted before passing to it. Another reason to question the def self.method notation is the ability to define private and protected methods. We can instantiate (“order”) a new instance from our Calculator class, and call the method sum on it like so: calculator = Calculator. Railstips has a nice article with more detail and a discussion of alternative ways of creating both class methods and instance methods. The code below yields the error: "rb:29:in 'again': undefined local variable or method 'add_num' for [object ID] NameError)." You know how to pass arguments (extra bits of information) to the method call. sum (2, 3) This will output 5. Now let's call these methods by passing integer values: add(20, 45) => 65 # returns 65 subtract(80, 10) => 70 # returns 70 What is less obvious is that Ruby actually allows us to pass a method call as an argument to other methods. A method in Ruby is a set of expressions that returns a value. This abstraction could result in another module. 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