Namespace and Class Directives

[TylerDM]

Namespace and Class Directives

Summary

Allow namespace and class to have Using Directive-like syntax.

Motivation

• Primary
  • Remove boilerplate braces found in 99% of C# files.
  • Remove boilerplate indentation found in 99% of C# files.
  • Removing 4-5 lines of code means that we see more of the file immediately upon opening.
• Secondary
  • Reduce line count at no real world cost. It's unfortunate that LoC is used as a decision making metric, but it does happen.

Detailed design

If you've ever taken a C# course, you've probably seen a class like this at least once.

using System;

namespace Animals
{
    public class Dog
    {
        private readonly string _breed;

        public Dog(string breed)
        {
            _breed = breed;
        }

        public void Bark() => Console.WriteLine($"The {breed} dog barks.");
    }    
}

I propose removal of the braces from using and class and assume they contain the entire file;

using System;

namespace Animals;
public class Dog;

private readonly string _breed;

public Dog(string breed)
{
    _breed = breed;
}

public void Bark() => Console.WriteLine($"The {breed} dog barks.");

This is quite a lot better! We've eliminated the boiler plate code that never changes in 99% of C# files. We've also eliminated 2 tabs on nearly the entire file. Costs? None. We can take this just a hair further as well:

The basic concept works well for record and other similar concepts.

using System;

public record Animals.Dog(string Breed);

Drawbacks

I personally do not like having multiple syntaxes for the same feature. In this case, however, I think it makes sense. You can use the old syntax for multiple namespaces or classes in a single file, should you want to. The old syntax would also be useful for nested classes. And then use the new syntax for the 99% of the time that those things aren't desired or needed.

This does reinforce a specific coding style of having one class per file. I have mixed feelings about catering C# to any particular style or use case. That said, the one class per file style is so ubiquitous that I believe the pragmatic benefits outweigh the philosophical drawbacks.

Alternatives

Combine the namespace and class directives into a single directive.

using System;

public class Animals.Dog;

private readonly string _breed;

public void Bark() => Console.WriteLine($"The {breed} dog barks.");

public Dog(string breed)
{
    _breed = breed;
}

You could also allow multiple namespaces and class per file by allowing multiple directives, with the latest one taking precedence.

using System;

namespace Animals;

public abstract class Pet;
public abstract void Vocalize();

public class Dog : Pet;
public override void Vocalize() => Console.WriteLine("Woof!");

public class Cat : Pet;
public override void Vocalize() => Console.WriteLine("Meow!");

Unresolved questions

None known.

Design meetings

None thus far.

[HaloFour]

See: #137

I don't see that being extended to class.

[ufcpp]

#4141