Could it ever be false or null?

Question

Can it selfever evaluate to false or nil?

For instance...

class FooBar

  ...

  def check_this
    self && check_something_else
  end
end

Is self &&this condition required ?

Answer 1

Yes. Remember that everything in Ruby is an object, therefore it selfis false for falseand nil:

nil.instance_eval { self }  # => nil
false.instance_eval { self }  # => false

Answer 2

Yes, but only in some very strange circumstances:

irb(main):001:0> def false.test
irb(main):002:1>   puts "hello" if !self
irb(main):003:1> end
=> nil
irb(main):004:0> false.test
hello
=> nil

Answer 3

, self nil false .

nil false Ruby . self nil false :

def nil.self
  self
end
nil.self
=> nil

def false.self
  self
end
false.self
=> false

, , , , .

Answer 4

Here is the corresponding article by Avdi Grimm on this issue, it seems impossible to fake the object, if only in very strange circumstances after NilClassor falseI suppose.

Answer 5

class NilClass
  def selfie
    self
  end
end

nil.selfie #=> nil

class FalseClass
  def selfie
    self
  end
end

false.selfie #=> false

Answer 6

This is actually impossible, because - if the object is zero or false - you cannot call a method on it because it does not belong to the class.