One Class Per File Rule in .Net

One class per file rule in .NET?

One class per file also gives you a better idea of what each check in is changing without looking at the diffs of the file.

Multiple classes in a single .cs file - good or bad?

Simply say good practice is one class from one file. BUT if your application is quite small you can use several classes in one file.

Is it good practise to have multiple class definitions in one file?

I prefer one class per file. You'll never have to search for the correct filename because it is always the class name.

Is it a bad practice to have multiple classes in the same file?

I think you should try to keep your code to 1 class per file.

I suggest this because it will be easier to find your class later. Also, it will work better with your source control system (if a file changes, then you know that a particular class has changed).

The only time I think it's correct to use more than one class per file is when you are using internal classes... but internal classes are inside another class, and thus can be left inside the same file. The inner classes roles are strongly related to the outer classes, so placing them in the same file is fine.

The classes of a Model should be in one file or in several files? Or when to use them?

It doesn't matter whether they're in one or multiple files. Though, there is a standard of having all of your types in their own .cs file.

ViewModels\User.cs:

namespace App.Models
{
    public class User
    {
        public string Name{get;set;}
    }
}

ViewModels\Message.cs:

namespace App.Models
{
    public class Message
    {
        public string Content{get;set;}
    }
}

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Relevant Post - One class per file rule in .NET?

C# classes in separate files?

While the one class per file policy is strictly enforced in Java, it's not required by C#. However, it's generally a good idea.

I typically break this rule if I have a very small helper class that is only used by the main class, but I prefer to do that as a nested inner class for clarity's sake.

You can however, split a single class into multiple files using the partial keyword. This is useful for separating your code from wizard-generated code.

How to organize classes in a C Sharp application?

I recommend using one file per type. There's no economy in restricting the number of files and one file per type really helps with finding a type in your solution.

Quite often, files are organised in folders to help with levels of organisation (the folders are often named along namespace lines as these provide natural groupings of your types) although that is not always done.

Should I place every class in separate file?

That depends greatly of personal preference, but I like to do it.

In this case, I would have a folder inside my application called ValueConverters, and put all converters, including short ones, inside their own files.

I find it makes it easier to get an overview of what your project consist of from the Solution Explorer.

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