CODEWITHSUNDEEP
ruby-on-railsruby
user1801879
user1801879

Reputation: 822

Why is this instance variable being assigned

I was reading an article about ruby service objects at: http://code.tutsplus.com/tutorials/service-objects-with-rails-using-aldous--cms-23689

I'm not understanding why @user_data_hash is being assigned a value. It is not being used anywhere in the code. I've seen few other examples doing same thing in other articles I've read. What is the need of assigning to this instance variable?

class CreateUserService < Aldous::Service
  attr_reader :user_data_hash

  def initialize(user_data_hash)
    @user_data_hash = user_data_hash
  end

  def default_result_data
    {user: nil}
  end

  def perform
    user = User.new(user_data_hash)

    if user.save
      Result::Success.new(user: user)
    else
      Result::Failure.new
    end
  end
end

Upvotes: 0

Views: 53

Answers (2)

spickermann
spickermann

Reputation: 107117

@user_data_hash is used, because

attr_reader :user_data_hash

is a macro for:

def user_data_hash
  @user_data_hash
end

That means: This line user = User.new(user_data_hash) in the perform method will read the hash assigned to @user_data_hash:

Upvotes: 2

Logan Serman
Logan Serman

Reputation: 29880

attr_reader defines a method called user_data_hash, which returns @user_data_hash. So it is being used whenever you call user_data_hash.

Upvotes: 1

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