ActivatableClass
Represents a class that can be activated dynamically by the system or other components.
Description
The ActivatableClass is a fundamental concept in the Windows Runtime (WinRT) and Universal Windows Platform (UWP) development. It defines the contract for classes that can be instantiated at runtime, often without direct instantiation code in the calling assembly. This is crucial for extensibility, plugin architectures, and dynamic loading of components.
Key Concepts
- Dynamic Instantiation: Allows components to be created on demand.
- Activation Factories: The underlying mechanism that manages the creation of activatable class instances.
- Componentization: Enables breaking down applications into smaller, independently deployable units.
Syntax
[Activatable(typeof(MyActivatableClassFactory), 1.0)]
public sealed class MyActivatableClass : IMyInterface
Usage Example
This example demonstrates how to mark a class as activatable and how it might be used.
Defining an Activatable Class
To make a class activatable, you typically use attributes provided by the Windows Runtime metadata or specific SDKs. While the direct ActivatableClass attribute might not be exposed directly in C# for typical UWP apps (it's more of a COM/WinRT infrastructure concept), the principle applies to classes intended for activation.
In C#, classes intended for activation, especially those that can be instantiated via COM interop or WinRT projections, are often implicitly activatable if they implement public interfaces and have a public default constructor.
Activating a Class (Conceptual)
In a real scenario, activation would involve using WinRT APIs or COM interfaces to get an instance of the class by its ProgID or GUID. For demonstration purposes, let's imagine a conceptual activation:
// This is a conceptual example, actual activation might use WinRT APIs
// like `Activator.CreateInstance` for COM or specific WinRT activation functions.
// Assume 'MyActivatableClass' is defined elsewhere and is known by the system
// through its metadata or registration.
try
{
// Imagine a method to get an instance of an activatable class
IMyInterface instance = (IMyInterface)System.Activator.CreateInstance(Type.GetType("MyNamespace.MyActivatableClass, MyAssembly"));
// Now you can use the instance
instance.DoSomething();
}
catch (Exception ex)
{
// Handle activation errors
System.Diagnostics.Debug.WriteLine($"Error activating class: {ex.Message}");
}