Class inherits from

I wanted to know if a class was an Active Record class. I couldn’t find an easy way to do it in Ruby so I monkey patches the Class object like so (assuming Person is an active record model object).

class Class
  def inherits_from?(klass, me=self)
    return false if me.nil?
    return true if me == klass
    inherits_from? klass, me.superclass
  end
end

>> Person.inherits_from? ActiveRecord::Base
=> true

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This entry was posted on Sunday, August 3rd, 2008 at 6:41 am and is filed under Home. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

  1. Marcus Crafter says:
    August 3, 2008 at 6:41 am

    Hi Mark,

    I think you can do this using ancestors as well mate:

    $> irb
    >> class A; end
    => nil
    >> class B < A; end
    => nil
    >> B.ancestors
    => [B, A, Object, Kernel]
    >> A.ancestors
    => [A, Object, Kernel]

    Hope this helps.

    Cheers,

    Marcus

  2. Mark Mansour says:
    August 3, 2008 at 6:41 am

    Great tip Marcus – I’m going to convert this code (or maybe just remove it)

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