NoConditionals

Conditional statements, like if/else, have it's place, under libraries and frameworks, but not in application code. This library implements a collection of techniques to avoid if/else, initially by extending "Truthy" and "Falsey" classes with expressive yet Ruby idiomatic operations. Please look forward for more features to come.

Getting started

Make sure you have Ruby 2.1 or above, and then add this line to your application's Gemfile:

gem 'no_conditionals'

And then execute:

$ bundle

Or install it yourself as:

$ gem install no_conditionals

Monkey patching Rails application

This library uses refinement to extend objects. Alternatively, you may also do the following:

Save this code to the Rails application folder as 'config/initializers/no_conditionals.rb'.

# config/initializers/no_conditionals.rb

Object.class_eval do
  include NoConditionals::Truthiness
end

NilClass.class_eval do
  include NoConditionals::Falseyness
end

FalseClass.class_eval do
  include NoConditionals::Falseyness
end

And then restart the server.

Usage

#hence method

Evaluates block if "Truthy" otherwise returns "Falsey"

using NoConditionals

true.hence { "Yes" } # => "Yes"

false.hence { "Yes" } # => false

nil.hence { "Yes" } # => nil

[1,2,3,4,5].find {|n| n.odd? }.hence {|odd| "found #{odd}" } # => "found 1"

["", "Ruby", "Smalltalk", nil ].first.hence(&:empty?) # => true

#otherwise method

Returns self if "Truthy" otherwise evaluates block.

using NoConditionals

true.otherwise { "No" } # => true

false.otherwise { "No" } # => "No"

nil.otherwise { "No" } # => "No"

#maybe method

Returns first argument if "Truthy". If "Falsey" it either returns second argument or returns "Falsey" when only one argument.

using NoConditionals

(3 > 2).maybe "Yes", maybe: "No" # => "Yes"

(1 > 2).maybe "Yes", maybe: "No" # => "No"

true.maybe "Yes" # => "Yes"

false.maybe "Yes" # => false

nil.maybe "Yes" # => nil

#maybe! method

Calls first argument if "Truthy". If "Falsey" it either calls second argument or calls nothing when only one argument.

using NoConditionals

(3 > 2).maybe! -> { puts "True" }, maybe: -> { puts "False" } # True

(1 > 2).maybe! -> { puts "True" }, maybe: -> { puts "False" } # False

true.maybe! -> { puts "True" } # True

false.maybe! -> { puts "True" } # => false

nil.maybe! -> { puts "True" } # => nil

Sample codes

Replacing if-else conditions in controllers

class SessionsController
  ...
  using NoConditionals

  def create
    user = User.find_by_email params[:email]
    user
      .authenticate(params[:password])
      .hence { logged_in(user) }
      .otherwise { unauthenticated }
  end
  ...
end

Extending models and null objects

class User
  include NoConditionals::Truthiness
  ...
end

class MissingUser
  include NoConditionals::Falseyness
  ...
end

Replacing Object#try() in Rails application views

<%= @article.author.hence(&:name).otherwise { "Anonymous" } %>

<%= current_user
      .hence(&:admin?)
      .hence { link_to 'Edit, edit_article_path(@article) }
      .otherwise { 'Read Only' } %>

Chaining methods

class WeatherService
  using NoConditionals

  def weather_for(report)
     report
       .hence( &:source )
       .hence( &:location )
       .hence( &:city )
       .hence( &:weather )
       .otherwise { 'unknown weather' }
  end
end

Contributing

1. Fork it ( https://github.com/RichOrElse/no-conditionals/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request