To use the 'I' prefix for interfaces or not to

Question

That is the question? So how big a sin is it not to use this convention when developing a c# project? This convention is widely used in the .NET class library. However, I am not

Answer 1

I think the main reason for the I-Prefix is not that those using it can see it's an interface but that those implementing/deriving from existing classes and interfaces can see more easily wether it's an interface or base class.

Another advantage is that it prevents stupid things like (If my Java memory serves me correctly):

List foo = new List(); // Why does it fail?

The third advantage is refactoring. If you move through your objects and read the code you can see where you forgot to code-by-interface. "A method accepting something with a type not prefixed with I? Fix it!".

I used it even in Java and found it quite usefull, but it always depends on the guidelines for your company/team. Follow them, no matter how stupid you may think they are, some day you will be happy they exist.