Part I: The C# Language
264
Partial Method Definitions
Partial classes may also define partial methods. Partial methods are defined in one partial class
definition without a method body, and implemented in another partial class definition. In both places,
the
partial keyword is used:
public partial class MyClass
{
partial void MyPartialMethod();
}
public partial class MyClass
{
partial void MyPartialMethod()
{
// Method implementation
}
}
Partial methods can also be static, but they are always private and can ’ t have a return value. Any
parameters they use can ’ t be
out parameters, although they can be ref parameters. They also can ’ t use
the
virtual , abstract , override , new , sealed , or extern modifier.
Given these limitations, it is not immediately obvious what purpose partial methods fulfill. In fact, they
are important when it comes to code compilation, rather than usage. Consider the following code:
public partial class MyClass
{
partial void DoSomethingElse();
public void DoSomething()
{
Console.WriteLine(“DoSomething() execution started.”);
DoSomethingElse();
Console.WriteLine(“DoSomething() execution finished.”);
}
}
public partial class MyClass
{
partial void DoSomethingElse()
{
Console.WriteLine(“DoSomethingElse() called.”);
}
}
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