A lot of my development is done with Code Smells. Whether I'm working on my own code or refactoring someone elses code, if I see some code and it smells funny, then I investigate further.

Recently I've come to realize there's a code smell which we can blame Microsoft (Anders) for! 

C# Code Regions. 

Back in the early days of .Net (ie 2000-2003), I used to moderately region my code. But since reading Martin Fowler's seminal Refactoring book where the concept of Code Smells was introduced, I found that I didn't need C# Regions.

So why are regions a Code Smell?

There are two types of regioning I've seen in code. Regions that group methods, properties, member variables, constructors etc together, and those which collapse a block of code. I'll deal with each separately.

Using Regions to group members.

In many companies, its commonplace (and even enforced practice) to group similar class members together and place a region block around them. I've even seen this as a coding doctrine inside Microsoft. The problem is that Visual Studio already has a facility to do this automatically. And it's been around in VS since it was called VJ++ and before that in VC. It's called the Class View window, accessed with the shift-ctrl-C shortcut. So why anyone would care about building a class "DOM" into their code using Regions, rather than rely on the Class View window I have no idea. Perhaps they're using Notepad?

Using Regions to hide blocks within a method.

This is when it gets really nasty. I've seen multi-hundred line long methods containing regions, and subregions and sub-subregions. I've seen switch() statements wrapped in a region, then each individual case have a region, then subregions inside of the region inside of the case. Switch statements are already a Code Smell, but having region after region after region is a sure-fire way of telling you the method is too long.

 
So, please, can we all resolve to stop using Regions?

Interestingly, there are many features that Java has started copying from C# - but regions were not one of those. Perhaps in C# v4 Microsoft can right the wrong and deprecate regions?