CODEWITHSUNDEEP
ruby-on-railsruby
Cannon Moyer
Cannon Moyer

Reputation: 3164

Check if subclass is instance of parent

I've got the following three classes:

class MessageBuilder
   def initialize(template)
       @template = template
       puts @template.instance_of? MessengerTemplate 
   end
end

class MessengerTemplate
    def initialize
        @default_template_id = "111111"
    end
end

class JobTemplate < MessengerTemplate
    def initialize(name)
        @name = name
        @template_id = "2222"
    end
end

I'm trying to check if a parameter passed to MessageBuilder#initialize is an instance of MessengerTemplate. If not, I need to throw an error.

When I call:

message = MessageBuilder.new(JobTemplate.new("Invoice"))

the following line in the constructor:

puts @template.instance_of? MessengerTemplate

prints FALSE.

Can someone please tell me what I am doing wrong here?

Upvotes: 0

Views: 1706

Answers (1)

jvillian
jvillian

Reputation: 20263

Try:

@template.is_a?(MessengerTemplate)

As noted in the docs:

Returns true if class is the class of obj, or if class is one of the superclasses of obj or modules included in obj.

MessengerTemplate is a superclass of @template, therefore @template.is_a?(MessengerTemplate) => true.

Upvotes: 6

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