Builds method chains such that you can execute functions inside of a predefined set of callbacks.

Add this line to your application's Gemfile:

gem "hollaback"

And then execute:

$ bundle

Or install it yourself as:

$ gem install hollaback

Sometimes you want to execute code in the context of hooks. With this gem you can build before, after, and around callbacks that are executed in the context of the given object. For befores and afters you can use either symbols or procs. For arounds you can use symbols.

First, create a Hollaback::Chain object that will represent all of the callbacks that will be called around a block of code.

require "hollaback"
chain = Hollaback::Chain.new

Then, specify the callbacks that will be called.

chain.before :say_hello
chain.before { puts "How are you?" }
chain.after :say_goodbye
chain.around :say

Then, provide a block of code around which the callbacks will be called.

compiled = chain.compile { "- Hollaback" }

Finally, call the compiled sequence of callbacks (with or without an optional context object on which the symbol callbacks should be defined).

class Callbacker
  def say_hello
    puts "Hello!"
  end

  def say_goodbye
    puts "Goodbye!"
  end

  def say(&block)
    puts "speaking... "
    puts yield
    puts "...done."
  end
end

compiled.call(Callbacker.new)

In the above example, the following will output to stdout:

speaking... 
Hello!
How are you?
Goodbye!
- Hollaback
...done.

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/kddnewton/hollaback.

The gem is available as open source under the terms of the MIT License.