Define Poro

Plain Old Ruby Object class builder from provided attribute list and block.

WARNING

Sadly assignment does not handle constants scope well:

RegisterUser = DefinePoro::As.new(:user, :params) do
  USER_TYPE = 1

  # logic for registering user
end

puts USER_TYPE #> 1 WHAT! constant is bound to outer context
puts RegisterUser::USER_TYPE #> NameError: uninitialized constant RegisterUser::XX

Conclusion - please use old plain ruby objects with initializer and attr_reader, fancy things are not always the best ones.

History

Rationale

I have been using Struct.new to dynamically create ruby objects that base their identity on functionality and not on values.

RegisterUser = Struct.new(:user, :params) do
  # logic for registering user
end

Then I looked what a Struct is: http://en.wikipedia.org/wiki/Struct_%28C_programming_language%29

From ruby side http://www.ruby-doc.org/core-2.2.0/Struct.html

So it is an object that acts like container for data. It implements Enumerable. But RegisterUser is not a data container, neither enumerable. So what is it?

I would say PORO (plain old ruby object).

It should be described as:

RegisterUser
  attr_reader :user, :params

  def initialize(user, params)
    @user, @params = user, params
  end

  # logic for registering user
end

Ruby guys are lazy so we would like to type something shorter - that's provided by DefinePoro:

RegisterUser = DefinePoro::As.new(:user, :params) do
  # logic for registering user
end

The DefinePoro::As implementation is easy and performant ruby code.

Should you use it?

Yes - if you are lazy to type initializers.

No - if you think that dynamic class definition could be harmful. And I believe that in some cases it could.

SURELY NOT - sadly assignment does not handle constants scope well.

Installation

Add this line to your application's Gemfile:

gem 'define-poro'

And then execute:

$ bundle

Or install it yourself as:

$ gem install define-poro

Usage

Instead of

RegisterUser
  attr_reader :user, :params

  def initialize(user, params)
    @user, @params = user, params
  end

  # logic for registering user
end

Define you class via

RegisterUser = DefinePoro::As.new(:user, :params) do
  # logic for registering user
end

Contributing

1. Fork it ( https://github.com/astrauka/define-poro/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Ensure that you have written specs (rspec)
5. Push to the branch (git push origin my-new-feature)
6. Create a new Pull Request

Changelog

0.1.0 - renamed DefinePoro::Define to DefinePoro::As