Pipe

pipe-ruby is an implementation of the UNIX pipe command. It exposes two instance methods, pipe and pipe_each.

Add this line to your application's Gemfile:

gem "pipe-ruby", :require => "pipe"

After bundling, include the Pipe module in your class(es)

class MyClass
  include Pipe

  # ...
end

pipe(subject, :through => [
  :method1, :method2#, ...
])

Just as with the UNIX pipe, subject will be passed as the first argument to method1. The results of method1 will be passed to method2 and on and on. The result of the last method called will be returned from the pipe.

pipe_each([subj1, subj2], :through => [
  :method1, :method2#, ...
])

pipe_each calls pipe, passing each individual subject. It will return a mapped array of the responses.

After implementing the pipe method in a few different places, we found that a slightly different version was needed for each use case. Pipe::Config allows for this customization per call or per class implementation. There are four configurable options. Here they are with their defaults:

Pipe::Config.new(
  :skip_on => false,            # a truthy value or proc which tells pipe to skip
                                # the next method in the `through` array

  :stop_on => false             # a truthy value or proc which tells pipe to stop
                                # processing and return the current value
)

A Pipe::Config object can be passed to the pipe method one of three ways.

NOTE: The options below are in priority order, meaning an override of the pipe_config method will take precedence over an override of the @pipe_config instance variable.

You can pass it to pipe when called:

class MyClass
  include Pipe

  def my_method
    config = Pipe::Config.new(:skip_on => false)
    subject = Object.new

    pipe(subject, :config => config, :through => [
      # ...
    ])
  end

  # ...
end

Or override the pipe_config method:

class MyClass
  include Pipe

  def pipe_config
    Pipe::Config.new(:skip_on => false)
  end

  # ...
end

Or you can assign it to the @pipe_config instance variable:

class MyClass
  include Pipe

  def initialize
    @pipe_config = Pipe::Config.new(:skip_on => false)
  end

  # ...
end

At the beginning of each iteration, Pipe::Config#stop_on is called. If it returns truthy, execution will be stopped and the current value of subject will be returned. A falsey response will allow the execution to move forward.

If not stopped, Pipe::Config#skip_on will be called. Truthy responses will cause the current value of subject to be passed to the next iteration without calling the method specified in the current iteration. Falsey responses will allow the specified method to be called.

Both skip_on and stop_on will receive three arguments when they're called, the current value of subject, the method to be called on this iteration and the value of #through.

First: please check out our style guides... we will hold you to them :)

1. Fork it ( https://github.com/[my-github-username]/pipe-ruby/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Make sure you're green (bundle exec rspec)
4. Commit your changes (git commit -am 'Add some feature')
5. Push to the branch (git push origin my-new-feature)
6. Create a new Pull Request

bundle exec rspec

We like to have good coverage of each major feature. Before contributing with a PR, please make sure you've added tests and are fully green.