Partial Methods In C#

What are Partial Methods In C#?

Ready has the concept of partial classes in C#, but I never knew that we can also have Partial Methods. Yes, we can have Partial Methods in C#. This concept also uses the Partial keyword but there are some restrictions/guidelines with the use of the Partial Methods.

public partial class ClassA
{
    public void SetSalary()
    {
        SetData();
        // Perform other functionality here
    }
    partial void SetData()
    {
        Console.Write("This is a partial method.");
        Console.ReadKey();
    }
}

Here is a list of attributes of a partial method.

1. A partial method can only be created in partial classes or partial structs.
2. In order to create a partial method, it must be declared first(like an abstract method), with a signature only and no definition. After it is declared, its body can be defined in the same component or a different component of the partial class/struct .
3. A partial method is implicitly private. It cannot have any other access modifier.
4. A partial method can only have a void return type.

Let's see how we can create a partial method. We start by creating a partial class ClassA and add a partial method declaration.

public partial class ClassA  
   {  
       partial void GetData();  
   }  

Now, create the second component of the partial class ClassA and add the implementation of the partial method. 

public partial class ClassA
{
    partial void SetData()
    {
        // Perform functionality here
    }
}

In order to test the partial method, we add another method and call this private method inside this newly created method.

class Program
{
    static void Main(string[] args)
    {
        ClassA cls = new ClassA();
        cls.SetSalary();
    }
}
public partial class ClassA
{
    partial void SetData();
}

public partial class ClassA
{
    public void SetSalary()
    {
        SetData();
        // Perform other functionality here
    }

    partial void SetData()
    {
        Console.Write("This is a partial method.");
        Console.ReadKey();
    }
}

class Program
{
    static void Main(string[] args)
    {
        ClassA cls = new ClassA();
        cls.SetSalary();
    }
}
public partial class ClassA
{
    partial void SetData();
}
public partial class ClassA
{
    public void SetSalary()
    {
        SetData();
        // Perform other functionality here
    }
    partial void SetData()
    {
        Console.Write("This is a partial method.");
        Console.ReadKey();
    }
}

Run the code and see the result. I hope you enjoyed reading it. Happy coding.

Next. Partial Classes in C#