CODEWITHSUNDEEP
rubymetaprogramming
CypressSDET
CypressSDET

Reputation: 69

How do I use Ruby metaprogramming to dynamically create a class with an initialize method?

Use Case: Read key/value pairs from yaml files and create classes for each of them. The dynamic classes should have an initialize method that calls the load_page_objects_with_globals method on each yml file.

Problem: The initialize method does not get implemented with each class created dynamically.

 def load_page_object_with_globals page_objects_file_name
    load_page_object_file(open("filepath/page_objects/#{page_objects_file_name}"))
    load_page_object_file(open("filepath/page_objects/global_page_object.yml"))
    puts page_objects_file_name
  end

  #dynamically creates methods based key/value pairs in yaml file
  def load_page_object_file(file)
    page_object = YAML.load(File.read(file))
    page_object.each do |k, v|
      self.class.__send__ :define_method, k do v end
    end
  end

  #
  def load_page_object_classes
    page_object_class_names = Array.new
    #camelizes the filenames into class name format
    Dir.glob("filepath/page_objects/*.yml").each do |item|
      filename = File.basename(item, ".*")
      filename = filename.dup.split(/[_-]/).map(&:capitalize).join("")
      page_object_class_names.push(filename)
    end
    puts page_object_class_names.inspect
    #PROBLEM CODE - dynamically create a class for each page object name and create initalize method
    page_object_class_names.each {
      |class_name|
      page_object_classes = Class.new(Object) do
        define_method(initialize) do
          load_page_object_with_globals(open("filepath/page_objects/#{class_name}.yml"))
        end
      end
      Class.const_set(class_name, page_object_classes)
      puts page_object_classes.inspect
    }
  end
  load_page_object_classes

Upvotes: 1

Views: 993

Answers (1)

alebian
alebian

Reputation: 782

Something like this worked for me:

require 'active_support/all'

def multiply_by(number1, number2)
  number1 * number2
end

hash = { foo: 1, bar: 2, baz: 3 }

hash.each do |k, v|
  klass_name = k.to_s.camelize
  klass = Class.new(Object) do
    define_method(:initialize) do |param|
      @test = multiply_by(v, param)
    end
  end
  Object.const_set(klass_name, klass)
end

puts Foo.new(1).inspect
puts Bar.new(2).inspect
puts Baz.new(3).inspect

Upvotes: 2

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