Why does Ruby have two send and __send__methods?

Question

Ruby objects have a method called send that we can call methods dynamically.

class MyClass
  private
  def true_method?
    true
  end
end

Example:

mc = MyClass.new
mc.send(:true_method?)
mc.__send__(:true_method?)

Why do you have these two methods?

Answer 1

Given that dynamic modifications such as method superscripts are common to see in Ruby, the Object#__send__ and Object#send is a way to protect objects against overwriting. The __send__ serves as an internal alias, which you can use if your object has some resetting of send. For example:

"hello world".send :upcase
=> "HELLO WORLD"

module EvilSend
  def send(foo)
    "Não foi dessa vez..."
  end
end

String.include EvilSend
"hello world".send :upcase
=> "Não foi dessa vez"

"hello world".__send__ :upcase
=> "HELLO WORLD"

Note that there is no Ruby Warning on the superscript of this method. That’s why there is __send__. The method that CANNOT be overwritten under any circumstances is the __send__. If you try, Ruby throws a warning.

Warning: Redefining '__send__' may Serious problems