Search code examples
rubymoduleextend

How to determine if an instance has been extended by a Ruby module?

Given an object and a module, how do I check that the object has been extended by the module?

There doesn't seem to be any corresponding extend? method

moirb(main):001:0> module Foobar
irb(main):002:1> end
=> nil
irb(main):003:0> o=Object.new
=> #<Object:0x000001010d1400>
irb(main):004:0> o.class.include? Foobar
=> false
irb(main):005:0> o.extend Foobar
=> #<Object:0x000001010d1400>
irb(main):006:0> o.class.include? Foobar
=> false
irb(main):007:0> o.class.included_modules
=> [PP::ObjectMixin, Kernel]
irb(main):016:0* o.methods.grep /extend/
=> [:extend]
irb(main):019:0> o.class.methods.grep /extend/
=> [:extend]
Solution

  • Is there any reason why you are not just using is_a?:

    o.is_a? Foobar
# => true