Sinclair
========
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![sinclair](https://raw.githubusercontent.com/darthjee/sinclair/master/sinclair.jpg)

This gem helps the creation of complex concern with class methods

Installation
---------------
  - Install it

  ```ruby
    gem install sinclair
  ```

  - Or add Sinclairn to your `Gemfile` and `bundle install`:

  ```ruby
    gem 'sinclair'
  ```

  ```bash
    bundle install sinclair
  ```

Yard Documentation
-------------------
https://www.rubydoc.info/gems/sinclair/

Usage
---------------
The concern builder can actully be used in two ways, as an stand alone object capable of
adding methods to your class or by extending it for more complex logics

 - Stand Alone usage:

  ```ruby

    class Clazz
    end

    builder = Sinclair.new(Clazz)

    builder.add_method(:twenty, '10 + 10')
    builder.add_method(:eighty) { 4 * twenty }
    builder.build

    instance = Clazz.new

    puts "Twenty => #{instance.twenty}"
    puts "Eighty => #{instance.eighty}"
  ```

  ```string

    Twenty => 20
    Eighty => 80
  ```

 - Extending the builder

  ```ruby

    class ValidationBuilder < Sinclair
      delegate :expected, to: :options_object

      def initialize(klass, options={})
        super
      end

      def add_validation(field)
        add_method("#{field}_valid?", "#{field}.is_a?#{expected}")
      end

      def add_accessors(fields)
        klass.send(:attr_accessor, *fields)
      end
    end

    module MyConcern
      extend ActiveSupport::Concern

      class_methods do
        def validate(*fields, expected_class)
          builder = ::ValidationBuilder.new(self, expected: expected_class)

          validatable_fields.concat(fields)
          builder.add_accessors(fields)

          fields.each do |field|
            builder.add_validation(field)
          end

          builder.build
        end

        def validatable_fields
          @validatable_fields ||= []
        end
      end

      def valid?
        self.class.validatable_fields.all? do |field|
          public_send("#{field}_valid?")
        end
      end
    end

    class MyClass
      include MyConcern
      validate :name, :surname, String
      validate :age, :legs, Integer

      def initialize(name: nil, surname: nil, age: nil, legs: nil)
        @name = name
        @surname = surname
        @age = age
        @legs = legs
      end
    end

    instance = MyClass.new
  ```

  the instance will respond to the methods
  ```name``` ```name=``` ```name_valid?```
  ```surname``` ```surname=``` ```surname_valid?```
  ```age``` ```age=``` ```age_valid?```
  ```legs``` ```legs=``` ```legs_valid?```
  ```valid?```

  ```ruby

    valid_object = MyClass.new(
      name: :name,
      surname: 'surname',
      age: 20,
      legs: 2
    )
    valid_object.valid? # returns true
  ```

  ```ruby

    invalid_object = MyClass.new(
      name: 'name',
      surname: 'surname',
      age: 20,
      legs: 2
    )
    invalid_object.valid? # returns false
  ```

RSspec matcher
---------------

You can use the provided matcher to check that your builder is adding a method correctly

  ```ruby

  class DefaultValue
    delegate :build, to: :builder
    attr_reader :klass, :method, :value

    def initialize(klass, method, value)
      @klass = klass
      @method = method
      @value = value
    end

    private

    def builder
      @builder ||= Sinclair.new(klass).tap do |b|
        b.add_method(method) { value }
      end
    end
  end

  RSpec.configure do |config|
    config.include Sinclair::Matchers
  end

  RSpec.describe DefaultValue do
    let(:klass)    { Class.new }
    let(:method)   { :the_method }
    let(:value)    { Random.rand(100) }
    let(:builder)  { described_class.new(klass, method, value) }
    let(:instance) { klass.new }

    context 'when the builder runs' do
      it do
        expect do
          described_class.new(klass, method, value).build
        end.to add_method(method).to(instance)
      end
    end

    context 'when the builder runs' do
      it do
        expect do
          described_class.new(klass, method, value).build
        end.to add_method(method).to(klass)
      end
    end
  end
  ```

  ```bash

  > bundle exec rspec
  ```

  ```string

  DefaultValue
    when the builder runs
        should add method 'the_method' to #<Class:0x0000000146c160> instances
    when the builder runs
        should add method 'the_method' to #<Class:0x0000000143a1b0> instances

  ```