Create a guard

Creating a new Guard is very easy. For example, to create a Guard named yoyo just create a new gem by running bundle gem guard-yoyo. Please make your Guard start with guard-, so that it can easily be found on RubyGems.

$ bundle gem guard-yoyo
$ cd guard-yoyo

Now extend the project structure to have an initial Guard:

.travis.yml  # bonus point!
CHANGELOG.md # bonus point!
Gemfile
guard-yoyo.gemspec
Guardfile
lib/
  guard/
    yoyo/
      templates/
        Guardfile # needed for `guard init <guard-name>`
      version.rb
    yoyo.rb
test/ # or spec/
README.md

Your Guard main class Guard::Yoyo in lib/guard/guard-yoyo.rb must inherit from Guard::Guard and should overwrite at least the #run_on_change task methods.

Here is an example scaffold for lib/guard/yoyo.rb:

require 'guard'
require 'guard/guard'

module Guard
  class Yoyo < Guard

    # Initialize a Guard.
    # @param [Array<Guard::Watcher>] watchers the Guard file watchers
    # @param [Hash] options the custom Guard options
    def initialize(watchers = [], options = {})
      super
    end

    # Call once when Guard starts. Please override initialize method to init stuff.
    # @raise [:task_has_failed] when start has failed
    def start
    end

    # Called when `stop|quit|exit|s|q|e + enter` is pressed (when Guard quits).
    # @raise [:task_has_failed] when stop has failed
    def stop
    end

    # Called when `reload|r|z + enter` is pressed.
    # This method should be mainly used for "reload" (really!) actions like reloading passenger/spork/bundler/...
    # @raise [:task_has_failed] when reload has failed
    def reload
    end

    # Called when just `enter` is pressed
    # This method should be principally used for long action like running all specs/tests/...
    # @raise [:task_has_failed] when run_all has failed
    def run_all
    end

    # Called on file(s) modifications that the Guard watches.
    # @param [Array<String>] paths the changes files or paths
    # @raise [:task_has_failed] when run_on_change has failed
    def run_on_changes(paths)
    end

    # Called on file(s) deletions that the Guard watches.
    # @param [Array<String>] paths the deleted files or paths
    # @raise [:task_has_failed] when run_on_change has failed
    def run_on_removals(paths)
    end

  end
end

Please take a look at the source code of some of the existing Guards for more concrete example and inspiration.

Alternatively, a new Guard can be added inline to a Guardfile with this basic structure:

require 'guard/guard'

module ::Guard
  class InlineGuard < ::Guard::Guard
    def run_all
    end

    def run_on_changes(paths)
    end
  end
end

@avdi has a very cool inline Guard example in his blog post A Guardfile for Redis.