Module Providers

IModuleBuilderProvider controls where the dynamic type generated for AsyncBlockExpression and EnumerableBlockExpression state machines is emitted. Two built-in implementations are provided.

---

Interface

public interface IModuleBuilderProvider
{
    ModuleBuilder GetModuleBuilder( ModuleKind kind );
}

public enum ModuleKind
{
    Async,
    Enumerable
}

---

Built-in Providers

DefaultModuleBuilderProvider

Emits state machine types into a long-lived, non-collectible dynamic assembly. This is the default.

public sealed class DefaultModuleBuilderProvider : IModuleBuilderProvider
{
    public static readonly IModuleBuilderProvider Instance;
}

• Assembly lifetime: application lifetime
• Unloadable: no
• Thread-safe: yes
• Suitable for: production use, most scenarios

CollectibleModuleBuilderProvider

Emits state machine types into a collectible AssemblyLoadContext. Types can be unloaded when all references are released, allowing memory to be reclaimed.

public sealed class CollectibleModuleBuilderProvider : IModuleBuilderProvider
{
    public static readonly IModuleBuilderProvider Instance;
}

• Assembly lifetime: until all references are released
• Unloadable: yes (via AssemblyLoadContext)
• Thread-safe: yes
• Suitable for: scenarios with many short-lived lambdas, plugin systems, test isolation

---

Usage

Default (Implicit)

// DefaultModuleBuilderProvider is used automatically -- no configuration needed
var asyncBlock = BlockAsync( Await( someTask ) );

Collectible Assembly

var options = new ExpressionRuntimeOptions
{
    ModuleBuilderProvider = CollectibleModuleBuilderProvider.Instance
};

var asyncBlock = BlockAsync(
    [result],
    Assign( result, Await( someTask ) ),
    result,
    options
);

Custom Provider

Implement IModuleBuilderProvider to emit types into a specific assembly or to integrate with a custom AssemblyLoadContext:

public class MyModuleBuilderProvider : IModuleBuilderProvider
{
    private readonly ModuleBuilder _module;

    public MyModuleBuilderProvider( AssemblyBuilder assembly )
    {
        _module = assembly.DefineDynamicModule( "StateMachines" );
    }

    public ModuleBuilder GetModuleBuilder( ModuleKind kind ) => _module;
}

var options = new ExpressionRuntimeOptions
{
    ModuleBuilderProvider = new MyModuleBuilderProvider( myAssemblyBuilder )
};

---

Notes

• Each call to GetModuleBuilder may return the same or a new ModuleBuilder depending on the implementation. The default implementations return the same module for all calls.
• In test projects, use CollectibleModuleBuilderProvider when generating many lambda compilations to avoid OutOfMemoryException from accumulated dynamic types.
• ModuleKind is passed to the provider to allow routing Async and Enumerable state machines to different modules if needed.