Ruby: invoke class methods in a module

Question

I have a module, whose purpose is to act on any given ActiveRecord instance.

For argument's sake, let's say that this method puts the string "match" if it matches certain properties with another instance of the same type.

module Foo
  def check_against_other_instances
    self.all.each do |instance|
      if self.respond_to? :color && self.color == instance.color
        puts "match"
      end
    end
  end
end

However, I can't just simply call self.all here, because self is an instance. How do I call the class method all from here?

@HunterMcMillen I can't reference the class name directly, because I don't know ahead of time which classes will be using it. — varatis
– varatis, Commented Jul 3, 2012 at 18:19

varatis · Accepted Answer · 2012-07-03 18:23:40Z

3

Ah.. found the solution almost right after I asked...

self.class.all.each do |instance| ...

answered Jul 3, 2012 at 18:23

varatis

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Comments

phoet · Accepted Answer · 2012-07-03 18:17:35Z

0

if you want to extend the behavior of rails classes, then you are best of using ActiveSupport::Concern!

http://apidock.com/rails/ActiveSupport/Concern

answered Jul 3, 2012 at 18:17

phoet

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Comments

BaronVonBraun · Accepted Answer · 2012-07-03 18:24:26Z

0

You can pull the name of a class from an instance and then constantize it.

For example, given a class Thing:

t = Thing.new
t.class.name
  # => "Thing"
t.class.name.constantize
  # => Thing

answered Jul 3, 2012 at 18:24

BaronVonBraun

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2 Comments

varatis Over a year ago

Thanks Baron. Unfortunately, just found the answer ;). Also, you don't need to call t.class.name... you can just simplify things and call t.class

BaronVonBraun Over a year ago

This is definitely a much more roundabout way of getting to the simpler solution that @varatis posted.

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