One class per file rule in .NET? [closed]

Answer 1

I hate it when people think in absolutes and say you should never do this or that with something subjective and nit-picky like this, as if we all need to conform to someones stupid idea of right and wrong. Bottom line: having more than one class per file is totally fine if it makes sense. By makes sense I mean things like:

1. Makes the code easier to digest and maintain
2. Makes the solution less annoying (scrolling through countless unnecessary files) and less slow
3. The dev team is okay with it as a local coding practice

A really good example of why I may want multiple classes per file:

Say I've got a few dozen custom exception classes, each one is a 4 liner, I could have a separate file for each one or I could group the exceptions and have a file per group. For me what seems the most rational/pragmatic approach is to group them, and just have a few files, because it's more efficient time/coding wise (I don't have to right-click -> Add Class, rename, 50 times), it keeps the solution less cluttered and better performing.

Answer 2

Yes for the sake of readability we should have one file per class!. Just jumped into a project. I see many classes in one file. it just makes it so hard for a new guy to understand it. shouldnt we think of maintainibility? when we develop a software? many times development will continue by other developers. We have namespaces to arrange our stuff, we dont need files to do that!.

Answer 3

One code item per file, yes.

Everything else is a malpractice - and, quite frankly, a sign of RAD victimness.

As soon as one starts proper software development (IoC, design patterns, DDD, TDD, etc...) and leaves the "omg lets get this done, I have no idea how, but I get paid" playground, one will see that this rule really, really, matters.

Answer 4

I find that grouping a class with it's standard factory class in the same file is very useful.

Answer 5

Sometime one class per file, but...

When multiple classes are stricly related, more than one class in the same source file is, IMHO, BETTER than dedicating a short source file to each class. The source is more readable and compact (and using #region the same source can be be more structured than before).

Consider also that sometimes it's NECESSARY to spread the same class across different files (using partial), since having a 20000+ line source file is not handy even with the RAM I have available (but this is another question).

Answer 6

I sometimes group more than one class within a file if they are tightly coupled and at least one of them is very small.

General 'best practice' is to have one file per class.