How to make a ruby case statement use equals to (==) rather than threequals (===)

Question

Ruby's case statement uses === by default. Is there a way to make it use 'equals to' (i.e. ==) instead?

The motivation for doing so is because I have 5 if statements that would very nicely be replaced by a switch, but I was a little surprised to learn that

datatype = "string".class

if datatype == String
puts "This will print"
end

is not the same as

case datatype
when String
puts "This will NOT print"
end

Answer 1

You cannot let case to not use ===, but you can redefine === to use ==.

class Class
  alias === ==
end

case datatype
when String
  puts "This will print"
end
# >> This will print

---

Alternatively, you can create a specific class for doing that.

class MetaClass
  def initialize klass
    @klass = klass
  end

  def ===instance
    instance == @klass
  end
end

def meta klass
  MetaClass.new(klass)
end

case datatype
when meta(String)
  puts "This will print"
end
# >> This will print