It happens all the time. A developer needs some functionality in their application so they start writing an interface and then an implementation to go with it. Then something doesn’t compile, the code doesn’t work right or they cannot figure out how to get their design to work. Next comes the inevitable question “How can I fix my interface?” The answer is “fix your interface by throwing it away.” To be fair it isn’t generally the developer’s fault they went this way. We are trained from an early (developer) age to write code like this. We hear about it in school. We go to our first job and they are using interfaces everywhere. The problem is it is the wrong approach. In this article I’m going to discuss why we (generally) have it backwards and how you can start doing things “the right way”.

It seems so simple. Someone posts an example of how to do something using a cool, new feature in C# and you try to use their code and it fails to compile. Or you see something documented as working and you try it and it fails to compile. Why is that? It actually is quite simple but probably not at all obvious to the average developer.

If you’ve never used a C# iterator before then it may seem like magic. But under the hood it isn’t doing anything you can’t already do yourself. It is a time saver and as such there are quick actions and analyzers to recommend that you use them. If you’re like me you use them without even thinking but it is still important to remember they are generated code. It really shouldn’t be necessary to understand the underlying implementation of how they work but sometimes you have to. Here’s an interesting oddity that I saw recently with iterators.