state_machine

https://github.com/pluginaweek/state_machine

Ruby

Adds support for creating state machines for attributes on any Ruby class

StateMachine::Branch#state_requirements

One or more requirements for verifying the states being matched.  All
requirements contain a mapping of {:from => matcher, :to => matcher}.

Source | Google | Stack overflow

Edit

git clone [email protected]:pluginaweek/state_machine.git
cd state_machine
open lib/state_machine/branch.rb

Contribute

# Make a new branch
git checkout -b -your-name--update-docs-StateMachine--Branch-state_requirements-for-pr

# Commit to git
git add lib/state_machine/branch.rbgit commit -m "better docs for StateMachine::Branch#state_requirements"

# Open pull request
gem install hub # on a mac you can `brew install hub`
hub fork
git push <your name> -your-name--update-docs-StateMachine--Branch-state_requirements-for-pr
hub pull-request

# Celebrate!