Components Just Enough Structure
summary
Describes a tiny Clojure library that models stateful pieces as immutable records/maps and wires them into a system map that does a dependency graph and topological sort to call a start/stop lifecycle on each component, returning updated components. Uses associative injection so tests swap DB/email stubs by assoc before start, supports protocol-based stubs and per-test fresh databases, is implemented with a few helpers (update-system, reverse), works in practice and helps split monoliths, but cannot start/stop partial systems at runtime.
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chapters (27)
- 0:00Intro
- 2:31Structure Built-In
- 3:13Not a Lot of Structure
- 4:47One Big Map
- 8:24State Wrapper
- 9:33Public API
- 10:24Lifecycle: Constructor
- 11:03Lifecycle: Transitions
- 12:45Service Provider
- 13:56Domain Model
- 16:37Constructor with Dependencies
- 17:49System Map
- 19:13Starting a System
- 22:16Associative Injection
- 23:19Stub Service for Testing
- 24:30DB for Testing
- 25:37Testing Business Logic
- 27:07Var Substitution & Asynchrony
- 29:54Entry Point: main
- 30:16Entry Point: JSVC
- 30:50Entry Point: Web Request
- 31:40Inject Components Into Routes
- 32:28Web Server Component
- 33:23Tricks & Extensions
- 34:58System Lifecycle
- 36:07Merging Systems
- 38:47Disadvantages
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