July 30, 2017

...Learn TDD with Codemanship

Clean# - My Imaginary C# Compiler Extension

Almost a decade ago, I wrote an article for the now-defunct itarchitect.co.uk that predicted the rise of real-time code quality analysis as we type.

What we were waiting for was more number-crunching power, and I think perhaps that day has arrived. So, too, has the technology we'd need to achieve it. Microsoft's Roslyn compiler platform offers the ability to perform real-time ("live") code analysis and report it in much the same way editors of old reported syntax errors.

This raises the prospect for detecting common code smells as they appear. and even fix some of them automatically.

Consider an example: Long Parameter Lists. As we type our method declaration, we type one parameter, then another parameter, then another, and then... as type the fourth parameter, a squiggly line appears underneath it. Hovering over that shows a warning: "Too many parameters". And then potential fixes would drop down, like introducing a parameter object, or accessing data through a private getter, if that's possible, or even splitting the method into two methods to be called in succession (assuming the client code is in the same class, otherwise we'd be introducing Feature Envy.)

Or how about this? We type a call to a method on an instance of a collaborating class. Then we type a call to a second method on the same object. At which point that whole expression, statement or code block (or entire method, if all calls are to this other object) lights up with a message warning "Feature Envy". We're then offered fixes like extracting the offending code into a separate method and moving it to the other class.

I can see a range of code smells being detected as we type: long methods, too many branches/loops, too many dependencies, large classes, and many more. I can even envision a strict mode, where we not only get warnings about certain code smells, but the code actually won't compile until they've been fixed.

Let's call this imaginary C# compiler extension Clean#, because everything has to have a cool name even when it doesn't exist yet.

And as computing power continues to increase (16-core, 32-core, etc etc), I can see the analysis getting much more sophisticated. As we type, code could be analysed to check if it's reachable from unit tests, for example.

The future is here. Now, where's my hover car?

Posted 6 hours, 39 minutes ago on July 30, 2017