Obsolete

The C# Obsolete attribute generates a compile-time warning. When a method has the Obsolete attribute, the C# compiler issues a warning if it is called.

This attribute helps keep programs correct. This makes it easier to transition from old methods. It can help improve overall code quality.

To begin, the Obsolete attribute is found in the System namespace. It is an attribute type, which means you can specify the type as Obsolete or ObsoleteAttribute.

using System;

class Program
{
    static void Main()
    {
        MethodA();
    }

    [Obsolete("Use MethodB instead")]
    static void MethodA()
    {
    }
}
... warning CS0618: 'Program.MethodA()' is obsolete: 'Use MethodB instead'

Attribute info

Attributes are invoked the same way as constructors. The Obsolete attribute can have zero arguments. In this case, a generic compile-time warning is generated.

Obsolete is useful for version updates. If you have developed a new control flow and a certain method is no longer wanted, you can decorate it with the Obsolete attribute.

Final notes

Once you have added Obsolete, you can correct warnings or errors as you go along. In larger projects this can help coordinate the methods different programmers employ.