On

Dynamic callbacks for Ruby blocks.

Inspired by http://www.mattsears.com/articles/2011/11/27/ruby-blocks-as-dynamic-callbacks

Usage

Basic usage.

require 'on'

def tweet(message, &block)
  callback = On.new(:success, :failure, &block)
  callback.call :success
rescue => e
  callback.call :failure, e.message
end

tweet "hello world" do |callback|
  callback.on :success do
    # handle success
  end
  callback.on :failure do |error_message|
    # handle error message
  end
end

Usage with proc

Syntatic sugar for creating an on callback from Proc.

require 'on/proc'

def tweet(message, &block)
  callback = block.on(:success, :failure)
  callback.call :success
rescue => e
  callback.call :failure, e.message
end

tweet "hello world" do |callback|
  callback.on :success do
    # handle success
  end
  callback.on :failure do |error_message|
    # handle error message
  end
end

Testing with On::TestHelper

require 'minitest/autorun'
require 'on'
require 'on/test_helper'

class SomeTest < MiniTest::Spec
  include On::TestHelper

  let(:recorder) { On::TestHelper::Recorder.new }

  it "records everything" do
    on = On.new(:success, :failure, &recorder)
    on.call :success, :some, :args
    assert_callback recorder, :success, :some, :args
  end

  it "calls nothing" do
    on = On.new(:success, :failure, &recorder)
    # nothing called
    refute_callbacks recorder
  end

  it "records everything manually" do
    on = On.new(:success, :failure) do |result|
      recorder.record_block
      recorder.record_callback(result, :success, :failure)
    end
    on.call :success, :some, :args
    assert_callback recorder, :success, :some, :args
  end
end

Installation

Add this line to your application's Gemfile:

gem 'on', '~> 1.0.0'

And then execute:

$ bundle

Or install it yourself as:

$ gem install on

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request

Release

Follow these steps to release this gem:

# Bump version in
edit lib/on/version.rb
edit README.md

git commit -m "Release X.Y.Z"

rake release

on