Hash Presenter demonstration

example.rb

class SomePresenter < HashPresenter
  present 'author',    :author
  present 'something', :something
  present 'foo',       :foo
  
  def baz
    "#{self.author} is #{self.something}"
  end
end

presenter = SomePresenter.new({
  'author' => 'Matthew',
  something: 'important',
  foo: {
    bar: 'qux'
  }
})

presenter.foo #=> { "bar" => "qux" }
presenter.author #=> 'Matthew'
presenter.baz #=> 'Matthew is important'

hash_presenter.rb

# A very light wrapper for a hash. It will allow you to present the hash in
# an object like manner without a ton of extra cruft
class HashPresenter
  def self.present(key, as, options={})
    options = { writer: true, reader: true }.merge(options)
    reader = as
    writer = "#{as}="

    if options[:reader]
      define_method(reader) do
        self[key]
      end
    end

    if options[:writer]
      define_method(writer) do |object|
        self[key] = object
      end
    end
  end

  def initialize(params={})
    @hash = ActiveSupport::HashWithIndifferentAccess.new(params)
  end

  def [](key)
    @hash[key]
  end

  def []=(key, value)
    @hash[key] = value
  end

  def fetch(key, default=nil, &block)
    if respond_to?(key)
      value = self.send(key)
      if value
        value
      else
        block_given? ? yield(key) : default
      end
    else
      @hash.fetch(key, default, &block)
    end
  end
end