Is the initialize method a built-in method in Ruby?

methods, ruby

Solution

You can consider the relationship between the `Class#new` method and each class's `#initialize` method to be implemented more or less like this:

class Class
  def new
    instance = allocate()

    instance.initialize

    return instance
  end
end

class Foo
  def initialize
    # Do nothing
  end
end

You can create a class without explicitly defining an `#initialize` method, because the `#initialize` method is defined by default to do nothing, and its return value is always ignored (regardless of what value you return).

The arguments you pass to `Class#new` are always passed directly to `#initialize` in the same order and format. For example:

class Class
  def new (arg1, arg2, &block_arg)
    instance = allocate()

    instance.initialize(arg1, arg2, &block_arg)

    return instance
  end
end

class MyClass
  def initialize (arg1, arg2, &block_arg)
    # Do something with args
  end
end

Problem

Is the initialize method a built-in method in Ruby? Why do we have to pass arguments when we create a new object, and why it goes directly to that initialize method? And, can we create a class without an initialize method?

Original source