Module: ExerciseOptions

Defined in:
lib/exercise_options.rb,
lib/exercise_options/version.rb

Defined Under Namespace

Classes: Error

Constant Summary collapse

VERSION = 
"0.1.0"

Class Method Summary collapse

Class Method Details

.for(**options) ⇒ Module

Decorate an upstream object with additional attributes. By including the generated module, ExerciseOptions will intercept a call to ‘new` and apply the declared options to the newly instantiated object.

Examples:

class MyObject
  def initialize(name:)
    self.name = name
  end
  attr_accessor :name
end

MyObject.prepend(
  ExerciseOptions.for(
    default_is_true: true,
    conditionally_true_with_receiver: ->(obj) { obj.name == "Hello World" },
  )
)

obj = MyObject.new(name: "Nobody")
expect(obj.default_is_true).to be_truthy
expect(obj.conditionally_true_with_receiver).to be_falsey

next_object = MyObject.new(name: "Hello World", default_is_true: false)
expect(next_object.default_is_true).to be_falsey
expect(next_object.conditionally_true_with_receiver).to be_truthy

Parameters:

  • options (Hash<Symbol, Object>) —

    a Hash with keys that are symbols. Each value may be either a lambda or not. When it is a lambda, that will be called at object initialization. When it is not a lambda, that will be the default value at object initialization.

Returns:

  • (Module) 


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# File 'lib/exercise_options.rb', line 42

def self.for(**options)
  Module.new do
    extend ActiveSupport::Concern
    class_methods do
      define_method(:new) do |*args, **kwargs, &block|
        super(*args, **kwargs.except(*options.keys), &block).tap { |instance|
          options.keys.each do |key|
            value = if kwargs.key?(key)
                      kwargs.fetch(key)
                    else
                      instance.send("default_#{key}")
                    end
            instance.public_send("#{key}=", value)
          end
        }
      end
    end

    options.each do |key, value|
      attr_accessor key
      define_method "default_#{key}" do
        if value.respond_to?(:call)
          if value.arity == 1
            value.call(self)
          else
            value.call
          end
        else
          value
        end
      end
    end
  end
end