A super-slim (~200 loc) statemachine-like support library focussed on use in Travis CI.
Note that the current version behaves slightly differently, and comes with
reduced features compared to the original version. If you are looking for the
original version see the tag v1.1.0.rc11
.
Define states and events like this:
class Foo
include SimpleStates
event :start, if: :start?
event :finish, to: [:passed, :failed], after: :notify, unless: :finished?
attr_accessor :state, :started_at, :finished_at
def start
# start foo
end
def start?
true
end
def notify(event)
# notify about event on foo
end
end
SimpleStates expects your model to support attribute accessors for :state
.
Event options have the following well-known meanings:
:to # allowed target states to transition to, deferred from the event name if not given
:if # only proceed if the given method returns true
:unless # only proceed if the given method returns false
:before # run the given method before running `super` and setting the new state
:after # run the given method at the very end
All of these options except can be given as a single symbol or string or as an Array of symbols or strings.
Calling event
will effectively add methods to a proxy module which is
prepended to your class (included to the singleton class of your class'
instances on 1.9). E.g. declaring event :start
in the example above will add
methods start
and start!
to a module included to the singleton class of
instances of Foo
.
This method will
- check if
:if
/:unless
conditions apply (if given) and just return from the method otherwise - run
:before
callbacks (if given) - set the object's
state
to the target state - set the object's
[state]_at
attribute toTime.now
if the object defines a writer for it - call
super
if Foo defines the current method (i.e. callstart
but notfinish
in the example above) - run
:after
callbacks (if given)
You can define options for all events like so:
event :finish, after: :cleanup
event :all, after: :notify
This will call :cleanup first and then :notify on :finish.
If no target state was given for an event then SimpleStates will try to derive
it from the event name. I.e. for an event start
it will check the states
list for a state started
and use it. If it can not find a target state this
way then it will raise an exception.