Get your filthy hands off my Kernel methods

Using pre-existing libraries can save you development time. Unfortunately, the quality of Ruby plugins and gems can be highly variable.

Kernel#__method__ as defined in the aws-s3 gem:

unless (RUBY_VERSION[0,3] == '1.9')
  module Kernel
    def __method__
      /\`([^\']+)\'/.match(caller(1).first)[1].to_sym
    end 
    # ...
  end
end

Kernel#__method__ as defined in the facets gem:

module Kernel
  def __method__(depth = 0)
    caller[depth][/`([^']+)'/, 1]
  end if RUBY_VERSION <= '1.8.7'
  # ...
end

Can you guess what happens when both are loaded?

One definition wins. Something breaks.

So which one is right?

Neither.

Please don’t write code like this.