WorkflowToHash
A tool to allow a sequence of actions in a state machine to be defined as an array.
Installation
Add this line to your application's Gemfile:
gem 'workflow_to_hash'
And then execute:
$ bundle
Or install it yourself as:
$ gem install workflow_to_hash
Usage
This tool has been specifically designed to work with Piotr Murach's FiniteMachine but is not limited to that environment.
When building state matchines, I regularly find that state needs to move in a sequence of
steps. For example, :one
to :two
to three
. In FiniteMachine, to achieve that you
can do this:
require 'finite_machine'
class StateMachine < FiniteMachine::Definition
initial :one
events {
event(
:next,
:one => :two,
:two => :three
)
}
end
sm = StateMachine.new
sm.state # --> :one
sm.next
sm.state # --> :two
sm.next
sm.state # --> :three
That is OK, but gets a little unwieldy as the sequence grows or when you want to swap out sequences depending on a condition.
WorkflowToHash allow me to create state sequences more easily. For example, to achieve the above I could:
require 'finite_machine'
require 'workflow_to_hash'
class Workflow < WorkflowToHash::Workflow
def forward
[:start, :one, :two, :three]
end
def backward
[:start, :three, :two, :one]
end
end
class StateMachine < FiniteMachine::Definition
initial :start
events {
event(
:next,
Workflow.for(:forward)
)
}
end
sm = StateMachine.new
sm.state # --> :start
sm.next
sm.state # --> :one
sm.next
sm.state # --> :two
sm.next
sm.state # --> :three
And then it allows me to build more complex state machines succinctly:
class StateMachine < FiniteMachine::Definition
initial :start
events {
event(
:next,
Workflow.for(:forward).merge(if: -> {target.forward})
)
event(
:next,
Workflow.for(:backward).merge(if: -> {!target.forward})
)
}
end
require 'ostruct'
forward = OpenStruct.new forward: true
backward = OpenStruct.new forward: false
sm = StateMachine.new
sm.target forward
sm.state # --> :start
sm.next
sm.state # --> :one
sm.next
sm.state # --> :two
sm.next
sm.state # --> :three
sm = StateMachine.new
sm.target backward
sm.state # --> :start
sm.next
sm.state # --> :three
sm.next
sm.state # --> :two
sm.next
sm.state # --> :one
Development
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
.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/reggieb/workflow_to_hash.
License
The gem is available as open source under the terms of the MIT License.