This example shows various types of Transition Handlers and the way params
get passed to them:
- negotiation handlers
- final handlers
- self handlers
It also makes use of Relations (`add`) to present the difference between
Requested and Implied states.
The handlers are using `this.to()` and `this.is()` methods fetch the Target
States of transitions.
Scroll down to see the log output.
https://github.com/TobiaszCudnik/asyncmachine
const { machine } = require('asyncmachine')
const assert = require('assert')
const example = machine({
Requested: { add: ['Implied'] },
Implied: {},
Delayed: {}
})
example.id('').logLevel(3)
// SETUP TRANSITIONS
example.Requested_enter = function(name, value) {
// target states inside of a negotiation handler are available as `this.to()`
assert(this.to().includes('Requested'))
assert(this.to().includes('Implied'))
assert(name == 'john')
assert(value == 5)
}
example.Requested_state = function(name, value) {
assert(this.is().includes('Requested'))
assert(this.is().includes('Implied'))
assert(name == 'john')
assert(value == 5)
this.addByListener('Delayed')(name, value)
}
example.Implied_state = function(name, value) {
assert(this.is().includes('Requested'))
assert(this.is().includes('Implied'))
// only the Requested states get the call params passed through
assert(name === undefined)
assert(value === undefined)
}
example.Delayed_state = function(name, value) {
assert(this.is().includes('Delayed'))
assert(this.is().includes('Requested'))
assert(this.is().includes('Implied'))
assert(name == 'john')
assert(value == 5)
// this will trigger a self transition, using the node-style callback
this.addByCallback('Delayed')(null, name, value)
}
example.Delayed_Delayed = function(name, value) {
assert(this.is().includes('Delayed'))
assert(this.is().includes('Requested'))
assert(this.is().includes('Implied'))
assert(name == 'john')
assert(value == 5)
}
// RUN
example.add('Requested', 'john', 5)
Log output (level 3):
[add] Requested
[add:implied] Implied
[transition] Requested_enter
[state] +Requested +Implied
[transition] Requested_state
[queue:add] Delayed
[postpone] postponing the transition, the queue is running
[transition] Implied_state
[add] Delayed
[state] +Delayed
Requested, Implied
[transition] Delayed_state
[queue:add] Delayed
[postpone] postponing the transition, the queue is running
[add] Delayed
[transition] Delayed_Delayed
[state] Delayed, Requested, Implied
no comments
sign in to comment