Factory Registry

Namespace: DesignPatterns.Creational

Overview

Map keys to product factories — similar to Strategy but for creating instances (Create() / IFactoryRegistry).

Runtime

• IFactoryRegistry<TKey, TProduct> — extends read-only registry with Create
• IAsyncFactoryRegistry<TKey, TProduct> — async variant with CreateAsync
• IPooledFactoryRegistry<TKey, TProduct> — pooled variant with RentAsync / Return (backed by ArrayPool<T>)
• FactoryRegistryBuilder<TKey, TProduct> — fluent manual registration
• AsyncFactoryRegistryBuilder<TKey, TProduct> — fluent manual async/pooled registration

Source generator

[RegisterFactory(typeof(TProduct), "key")] on factory types; partial static registry holder. Optional IsAsync = true for async factories and PoolSize = N for pooled factories.

[RegisterFactory(typeof(IProduct), "standard")]
public sealed class StandardProductFactory : IProductFactory { ... }

[RegisterFactory(typeof(IProduct), "premium", IsAsync = true)]
public sealed class PremiumProductFactory : IAsyncFactory<IProduct> { ... }

[RegisterFactory(typeof(IProduct), "buffer", PoolSize = 16)]
public sealed class BufferProductFactory : IAsyncFactory<IProduct> { ... }

When IsAsync = true or the factory implements IAsyncFactory<TProduct>, the generator emits an IAsyncFactoryRegistry in addition to the sync registry. When PoolSize > 0, the generator emits an IPooledFactoryRegistry.

Async factory registry

For asynchronous product creation, use IAsyncFactoryRegistry<TKey, TProduct>:

var registry = new AsyncFactoryRegistryBuilder<string, IProduct>()
    .Register("premium", ct => CreatePremiumAsync(ct))
    .Build();

var product = await registry.CreateAsync("premium");

Pooled factory registry

For reusable product instances with per-key object pooling, use IPooledFactoryRegistry<TKey, TProduct>:

var registry = new AsyncFactoryRegistryBuilder<string, IProduct>()
    .Register("buffer", () => new BufferProduct())
    .WithPooling(poolSize: 16)
    .Build();

var buffer = await registry.RentAsync("buffer");
// ... use buffer
registry.Return("buffer", buffer);

If a product implements IResettable, Reset() is called before returning it to the pool.

Diagnostics

DP020–DP023, DP025 (unknown literal keys). DP053–DP055 for async signature and pool size validation. See Registry key conventions.

Samples

Sample	Focus
Factory	Generated registry
RegisterFactory	Manual builder

Maintainer doc: docs/FactoryRegistry.md (中文).