Tinky-JSON

{
    "name" : "Test Workflow",
    "initial-state" : "new",
    "states" : [ "new", "open", "rejected", "in-progress", "stalled", "complete" ],
    "transitions" : [
        {
            "name" : "open",
            "from" : "new",
            "to"   : "open"
        },
        {
            "name" : "reject",
            "from" : "new",
            "to"   : "rejected"
        },
        {
            "name" : "reject",
            "from" : "open",
            "to"   : "rejected"
        },
        {
            "name" : "reject",
            "from" : "stalled",
            "to"   : "rejected"
        },
        {
            "name" : "stall",
            "from" : "open",
            "to"   : "stalled"
        },
        {
            "name" : "stall",
            "from" : "in-progress",
            "to"   : "stalled"
        },
        {
            "name" : "unstall",
            "to"   : "in-progress",
            "from" : "stalled"
        },
        {
            "name" : "take",
            "from" : "open",
            "to"   : "in-progress"
        },
        {
            "name" : "complete",
            "from" : "open",
            "to"   : "complete"
        },
        {
            "name" : "complete",
            "from" : "open",
            "to"   : "complete"
        },
        {
            "name" : "complete",
            "from" : "in-progress",
            "to"   : "complete"
        }
    ]
}

use Tinky;
use Tinky::JSON;

my $json = $*PROGRAM.parent.child('ticket.json').slurp;

my $workflow = Tinky::JSON::Workflow.from-json($json);

class Ticket does Tinky::Object {
    has Str $.ticket-number = (^100000).pick.fmt("%08d");
    has Str $.owner;
}

# Each state has an 'enter-supply' and a 'leave-supply' which get the
# object which the state was applied to.

$workflow.enter-supply('rejected').act( -> $object { say "** sending rejected e-mail for Ticket '{ $object.ticket-number }' **" });

# The transition supply allows specific logic for the transition to be performed

$workflow.find-transition('in-progress', 'stalled').supply.act( -> $object { say "** rescheduling tickets for '{ $object.owner }' on ticket stall **"});

# The workflow aggregates the Supplies of the transitions and the states.
# This could be to a logging subsystem for instance. 

$workflow.transition-supply.act(-> ($trans, $object) { say "Ticket '{ $object.ticket-number }' went from { $trans.from.name }' to '{ $trans.to.name }'" });

# The final-supply emits the state and the object when a state is reached where there are no
# further transitions available

$workflow.final-supply.act(-> ( $state, $object) { say "** updating performance stats with Ticket '{ $object.ticket-number }' entered State '{ $state.name }'" });

# Create an instance of the Tinky::Object.
# A 'state' can be supplied to initialise if, for example, the data was retrieved from a database
my $ticket-a = Ticket.new(owner => "Operator A");

# Applying the workflow will set the initial state if one is configured and will
# apply a role that provides the transition methods.
# The workflow object can be configured to check whether the object to which it
# is being applied is suitable and throw an exception if not.

$ticket-a.apply-workflow($workflow);

# Exercise the transition methods.
# Other mechanisms are available for performing the transitions whuch may be more
# suitable if the next state is to be calculated.

# State new -> open
$ticket-a.open;

# State open -> in-progress
$ticket-a.take;

# Get the names of the states which are now available for the object
# [stalled complete]
$ticket-a.next-states>>.name.say;

# Directly assigning the state will be validated, an exception will
# be thrown if this is not a valid transition at the time
$ticket-a.state = $workflow.state('stalled');

# State stalled -> rejected
# This is a final state and no further transitions are available.
$ticket-a.reject;