Partial Methods in C Sharp

Understand what partial methods are in C#, how they work alongside partial classes, and when to use them in code generation scenarios.

What is a Partial Method?

A partial method allows a method's signature to be declared in one part of a partial class, with its actual implementation optionally provided in another part, often used in code-generation scenarios.

How Partial Methods Work

If no implementation is provided for a partial method, the compiler simply removes all calls to it, meaning there's no performance overhead for unused partial methods, unlike regular empty methods.

Common Use Cases

Partial methods are frequently used in auto-generated code, such as Entity Framework model classes or Windows Forms designer files, allowing developers to hook into generated logic without modifying the generated file directly.

Rules and Restrictions

Partial methods must return void, cannot have access modifiers like public or private (they're implicitly private), and cannot have out parameters, which keeps their usage narrowly focused on optional extension points.