Just yesterday I learned a little something in Ruby that I found interesting. It’s the difference between __method__ and __callee__.

Both are supposed to return the name of the current method, but there’s a subtle difference:

• __method__: returns the name of the method as defined
• __callee__: returns the name of the method as called

I put together an example that illustrates the difference:

 class Bar
   def foo
     puts "__callee__ is #{__callee__}"
     puts "__method__ is #{__method__}"
   end
   alias :baz :foo
 end
 
 bar = Bar.new
bar.foo # => Prints "foo" and "foo"
bar.baz # => Prints "baz" and "foo"

This illustrates very well the difference between “message” and “method”. One is the name we use to invoke a method. The other is the name of the method ultimately called.