id_registry

Uniqueness and id generation across many collections of identifiers. id_pair_set says what ids one thing has; id_registry says which ids are already taken, in a form every collection you own can check against.

Why

Identifiers only do their job if they are unique across the whole store, not just inside one record. An ISBN registered to one book must not be registrable to another, and a code minted for a new thing must not collide with one that already exists. That is a property of the collection of collections, so it needs a home outside any single record — that home is this package.

What it does

• Registers sets: register takes an IdPairSet and checks every id against every id registered before. It is atomic — every id in the set is validated and checked before any of them is written, and a write that fails part way through is undone — so a refused registration leaves the registry exactly as it was.
• Unregisters sets, freeing the ids for reuse.
• Validators: attach an IdValidator (ISBN-10, ISBN-13, ORCID, or your own) to an id type and registration enforces the format.
• Generators: attach IdGeneratorType.autoIncrement or .uuid to an id type and generateId mints a free id and registers it before returning it.
• Pluggable storage: InMemoryIdStorage, FileBasedIdStorage (one JSON file, written through on every mutation) and CachedIdStorage (a decorator over either). All three run the same contract suite, so swapping them changes nothing a caller sees.

Failures are values

Every method answers with Either<IdRegistryFailure, …>: a duplicate, a code that fails its validator, a missing generator or an unwritable store comes back as a Left you can switch on — never as a thrown exception, and never as a half-finished operation. IdRegistryFailure is a sealed hierarchy, so a switch over it is exhaustive.

Concurrency

Mutating calls — register, unregister, generateId, clear — run one at a time inside the registry. Check-then-write is not atomic on its own: two registrations of the same id would otherwise both pass the check pass, and two generation calls would otherwise mint the same integer.

Usage

example/main.dart is the runnable tour (CI runs it on every push), and test/ is the reference for every behaviour above — including the atomicity and concurrency guarantees.

Add id_registry: ^2.0.0 to your pubspec.

Upgrading from 1.x

2.0.0 turned thrown exceptions into returned failures: register, unregister, generateId and clear answer with Either, IdRegistry became IdRegistryRepositoryImpl, and IdStorage methods now return Either too. The 2.0.0 section of CHANGELOG.md has the full list.

Related

id_pair_set — the identifiers this registry makes unique.

License

MIT. See LICENSE.