If a "Utilities" class is evil, where do I put my generic code?

Question

I generally live by the rule that Global variables / functions are evil and that every piece of code should live in the class to which it pertains.

This is a very easy rule to follow, and I believe that I haven't ever run into an issue with this rule until now.

Today, however, I need to add a function to my assembly rather than to a specific class. That is, almost all of my classes could have a use for this particular function.

Where should I put this function (+1 overload)?

If I put it in a "Utilities" class, I feel dirty. If I tack it on to a semi-related class, and let other classes call it directly, I feel worse.

This particular piece of code basically chops a IList<PointF> into a normalized list. I feel right now that adding it as an extension method on IList<PointF> may be the best bet...

Answer 1

You should put it into a 'ListUtilities' or PointListUtilities class, of course. Then you aren't breaking the single responsibility principle, which is the primary problem with a catch-all 'Utilities' class.

Answer 2

If this is an operation on an IList<PointF>, then it should be an extension method on IList<PointF>.

Generally, Utils and Helper type classes should be avoided. More often than not, you will find that what you may think is a utility method, is actually a rather specific method that probably belongs in a class of its own (just like you say). However, there will be domain specific cases where Util-like classes (classes which group related useful methods) are valid entities.

Answer 3

There is nothing wrong with "global" variables and methods. You use them all the time. The framework likes to call them "static" classes or "static" methods.

I rarely need to, but I usually add an internal static class Util in the namespace that the method/variable is needed for C# and a module for VB.NET.

Samples from .NET Framework

• System.Collections.Specialized.CollectionsUtil
• System.Net.WebUtility
• Check Microsoft's source code for .NET Framework. You will find numerous internal utility classes.