Pretty State Machine
summary
gen_statem exposes concrete features GenServer lacks: multiple actions on a transition (reply, emit events, set timeouts), the ability to postpone (replay) incoming messages into the front of the mailbox, and three timer types (event, state, generic) that differ in cancellation semantics. Performance measures claim parity with GenServer, there is an upgrade path from gen_fsm, and practical examples include an HTTP-client modeled as states where postponed requests queue and timers handle retries — the patterns work in practice.
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chapters (24)
- 0:00Intro
- 0:48Premise
- 1:07Objective
- 1:51Performance
- 2:22Documentation
- 3:26State
- 3:45Data
- 4:56Action
- 6:26Genesis
- 7:02Comb Home
- 7:19Mission
- 8:16State Functions
- 8:52State Name
- 10:29State Enter Functions
- 11:39Mailbox Events
- 12:32postpone
- 13:30selective receive
- 15:19eventtimeout
- 15:52statetimeout
- 16:27responsetimeout
- 18:56generictimeout
- 19:39reversibility
- 20:57resources
- 22:56intuition
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