IDGenerator

A flexible, keyed registry of ID generators for Swift.

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Overview

The IDGenerator package provides IDGeneratorValues, a keyed registry of generators that lets you decouple your code from any specific ID generation strategy — so you can swap in a deterministic generator during testing without changing the code under test.

Rather than coupling a component to a single generator type (e.g. UUID), you define a key per use case and inject only what each component needs:

struct UserRepository {
    @Dependency(\.idGenerators.userID) var userID
}

struct LogFileManager {
    @Dependency(\.idGenerators.logFilename) var logFilename
}

Each component declares the minimum dependency it requires. Swapping generators in tests is scoped to that one key, leaving everything else unaffected.

The package ships two libraries:

• IDGenerator — the core registry with no external dependencies.
• IDGeneratorDependency — optional integration with swift-dependencies by Point-Free.

Quick Start

1. Conform a Generator

Conform your generator type to IDGenerator and provide a default instance:

struct SequentialIDGenerator: IDGenerator {
    static let `default` = SequentialIDGenerator()

    func callAsFunction() -> Int { ... }
}

Note: If you're using IDGeneratorDependency, a IDGenerator conformance for UUIDGenerator is already provided out of the box — no extra setup needed.

2. Register a Key and Accessor

Define a GeneratorKey key and an IDGeneratorValues computed property, named after the use case — not the generator type:

extension GeneratorKey where Value == UUIDGenerator {
    static let userID = Self("userID")
}

extension IDGeneratorValues {
    var userID: UUIDGenerator {
        get { self[.userID] }
        set { self[.userID] = newValue }
    }
}

3. Inject and Use

Inject the scoped generator directly into your component:

struct UserRepository {
    @Dependency(\.idGenerators.userID) var userID

    func createUser() -> User {
        User(id: userID())
    }
}

4. Override in Tests

Use withDependencies to replace a single generator with a deterministic alternative:

@Test
func createsUserWithIncrementingID() {
    withDependencies {
        \$0.idGenerators.userID = .incrementing
    } operation: {
        let repo = UserRepository()
        let user = repo.createUser()
        #expect(user.id == UUID(uuidString: "00000000-0000-0000-0000-000000000000"))
    }
}

Installation

Add swift-id-generator to your Package.swift:

dependencies: [
    .package(url: "https://github.com/ShivaHuang/swift-id-generator", from: "0.1.0"),
],

Then add the product you need to your target:

• IDGenerator — core registry only, no external dependencies.
• IDGeneratorDependency — includes IDGenerator and integrates with swift-dependencies.

.target(
    name: "MyApp",
    dependencies: [
        // Core only:
        .product(name: "IDGenerator", package: "swift-id-generator"),

        // Or with swift-dependencies integration:
        .product(name: "IDGeneratorDependency", package: "swift-id-generator"),
    ]
),

Credits

The IDGeneratorDependency module is designed to work with swift-dependencies by Point-Free. Their library provides the dependency management infrastructure that IDGeneratorDependency builds upon.

License

This library is released under the MIT license. See LICENSE for details.