Until C# 8.0, an interface in C# could not contain method definitions. You could only include method declarations in an interface, and the members of an interface were public and abstract by default.

How not to use interfaces in C#. how-to. May 6, 2019 5 mins. C# Microsoft .NET Software Development. ... When designing an application, you will often need to use interfaces and abstract classes.

Default interface methods are included in a new feature proposal for C# 8, which will allow developers to use the traits programming technique. Based on an existing language feature found in Java ...

A controversial new proposal for .NET suggests the introduction of a limited form of multiple inheritance via abstract interfaces. This feature was inspired by Java’s default methods.