Scope

Services can be composed to use different scopes. Local scoped service can be created for a specific purpose, and be thrown away once purpose is completed.

In the following example TypeRequest is handled and cached in applicationScope and TypeBuilderRequest by buildScope. After building a type, the builder classes are discarded.

// Create application-scope service with cache
IService applicationScope = Services.Create(ServiceHandlers.Instance, CachePolicies.Default);
// Place instance here
object instance;
// Create build scoped service with cache to be disposed
using (var buildScope = Services.Create((applicationScope, EmitHandlers.Instance, RequestHandlers.Instance), CachePolicies.Default))
{
    // Create type building request
    IRequestFor<TypeBuilder> typeBuilder = new TypeBuilderRequest("HelloWorldClass");
    // Add ToString
    typeBuilder = typeBuilder.Append(ToStringRequest.Create("Hello World"));
    // Type request
    IRequestFor<Type> typeRequest = new TypeRequest(typeBuilder);
    // Instance request
    IRequestFor<object> newRequest = new NewRequest(typeRequest);
    // Create instance
    instance = buildScope.GetRequired<IRequestFor<object>, object>(newRequest);
}
// Scope is closed and type builder is disposed, type and instance remain in 'applicationScope'.
Console.WriteLine(instance);

Request as a tree, and by cache location.

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ applicationScope ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
NewRequest
└── Type = TypeRequest
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ buildScope ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
    └── Name = ContextRequest
        ├── Key = "System.Reflection.Emit.TypeBuilder"
        ├── Value = TypeBuilderRequest
        │   └── Name = "HelloWorldClass"
        └── Requests[0] = BatchRequest
            ├── Requests[0] = Emit
            │   ├── Opcode = ldstr
            │   ├── Parameters[0] = "Hello World"
            │   └── ILGenerator = ILGeneratorRequest
            │       └── Builder = MethodBuilderRequest
            │           ├── Name = "ToString"
            │           ├── Attributes = PrivateScope, Public, Virtual, HideBySig
            │           └── ReturnType = System.String
            └── Requests[1] = Emit
                ├── Opcode = ret
                └── ILGenerator = ILGeneratorRequest
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

Full example

using System;
using System.Collections.Generic;
using System.Reflection.Emit;
using Avalanche.Emit;
using Avalanche.Service;

public class service_scope
{
    public static void Run()
    {
        {
            // <1>
            // Create application-scope service with cache
            IService applicationScope = Services.Create(ServiceHandlers.Instance, CachePolicies.Default);
            // Place instance here
            object instance;
            // Create build scoped service with cache to be disposed
            using (var buildScope = Services.Create((applicationScope, EmitHandlers.Instance, RequestHandlers.Instance), CachePolicies.Default))
            {
                // Create type building request
                IRequestFor<TypeBuilder> typeBuilder = new TypeBuilderRequest("HelloWorldClass");
                // Add ToString
                typeBuilder = typeBuilder.Append(ToStringRequest.Create("Hello World"));
                // Type request
                IRequestFor<Type> typeRequest = new TypeRequest(typeBuilder);
                // Instance request
                IRequestFor<object> newRequest = new NewRequest(typeRequest);
                // Create instance
                instance = buildScope.GetRequired<IRequestFor<object>, object>(newRequest);
            }
            // Scope is closed and type builder is disposed, type and instance remain in 'applicationScope'.
            Console.WriteLine(instance);
            // </1>

            // Get cache
            (applicationScope as IEntryProviderBase).TryGetEntryCache(out IEntryCacheBase? cache);
            // Disconnect all cache lines
            cache!.TryDisconnectAll(out System.Collections.Generic.IEnumerable<KeyValuePair<object, IEntry>>? cacheLines);
            //
            foreach (var line in cacheLines!)
            {
                Console.WriteLine(line);
            }
        }

        {
            // <2>
            // Create application-scope service with cache
            IService applicationScope = Services.Create(ServiceHandlers.Instance, CachePolicies.Default);
            // Create build scoped service with cache to be disposed
            using (var buildScope = Services.Create((applicationScope, EmitHandlers.Instance, RequestHandlers.Instance), CachePolicies.Default))
            {
                // Print service as tree
                Console.WriteLine(buildScope.ToString());
            }
            // </2>
        }

    }
}


Scoped Services