Knowing your state machines
summary
Explains that state machines are simple directed graphs and shows concrete implementations: a Cron-driven email reminder using the state pattern versus a single-rule Mealy-style machine, a traffic light, job advert and PR workflows, multi-step forms and elevator doors. Uses the Symfony Workflow component (marking store, can/apply/transition, dumping to Graphviz) and hooks via the event dispatcher and guard events (about 21 events total). Demonstrates stateless rules-by-configuration and when to persist current state.
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chapters (13)
- 0:00Intro
- 0:38State machines
- 2:30Graph theory
- 5:15Graph constraints
- 12:02The state pattern
- 16:30Implementing the traffic light
- 22:02The workflow component
- 27:30Workflow vs state machine
- 29:37Event dispatcher
- 31:06Guard events
- 33:07Business logic
- 33:47In configuration
- 35:49Summary
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