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rubynullfixnum

Can Fixnum/Float be nil?

Can a Fixnum/Float be nil? Like can self even be nil in this case:

class Fixnum
  def clamp(min, max)
    if self == nil then nil end
    ...
  end
end
Solution

  • This is impossible because nil has its own class,NilClass:

    irb(main):001:0> nil.class
=> NilClass
irb(main):002:0> 456.class
=> Fixnum

    So a variable can either be a Fixnum or a NilClass but not both.

    In the context of a class instance method, self always refers to the instance, which is of the type of the class.

    Also self cannot be changed:

    irb(main):006:0> class C
irb(main):007:1>   def z
irb(main):008:2>     self = nil
irb(main):009:2>   end
irb(main):014:1> end
SyntaxError: (irb):8: Can't change the value of self
self = nil
      ^
        from D:/dev/Ruby20/bin/irb:12:in `<main>'