Composition

An IComposition is the immutable, thread-safe result of building capabilities. Once created, it cannot be modified — only replaced via recomposition.

Querying Capabilities

GetAll

IReadOnlyList<IPlugin> plugins = composition.GetAll<IPlugin>();
IReadOnlyList<object> everything = composition.GetAll();

First and Last

var first = composition.GetFirstOrDefault<IPlugin>();   // null if none
var last = composition.GetLastOrDefault<IPlugin>();     // null if none

Required Queries (throw if missing)

var first = composition.GetRequiredFirst<IPlugin>();    // throws InvalidOperationException
var last = composition.GetRequiredLast<IPlugin>();      // throws InvalidOperationException

Try-Pattern

if (composition.TryGetFirst<IPlugin>(out var plugin))
{
    plugin.Initialize();
}

if (composition.TryGetLast<ILogger>(out var logger))
{
    logger.Log("ready");
}

Has and Count

bool hasPlugins = composition.Has<IPlugin>();
int pluginCount = composition.Count<IPlugin>();

Primary Capability Queries

// Check existence
bool hasPrimary = composition.HasPrimary();
bool hasTyped = composition.HasPrimary<ServiceIdentity>();

// Get
IPrimaryCapability? primary = composition.GetPrimaryOrDefault();
IPrimaryCapability required = composition.GetPrimary();  // throws if none

// Typed access
if (composition.TryGetPrimaryAs<ServiceIdentity>(out var identity))
{
    Console.WriteLine(identity.Name);
}

var id = composition.GetRequiredPrimaryAs<ServiceIdentity>();  // throws if missing/wrong type
var idOrNull = composition.GetPrimaryOrDefaultAs<ServiceIdentity>();

Properties

Property	Type	Description
Subject	object	The subject this composition belongs to
TotalCapabilityCount	int	Total number of capabilities (across all types)

Thread Safety

Compositions are fully immutable after Build(). They can be safely shared across threads, cached, passed between components, and stored in concurrent collections without synchronization.