Guidance for using primary constructors when "_underscoreCamelCase" syntax is used for private fields?

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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[severity:It's more difficult to complete my work]
In every place I've worked at, the desired syntax for private fields is "_underscoreWithCamelCase". It's also the suggested convention in the C# coding style docs. For example, the dependency injection example would be written without primary constructor as follows:

public class ExampleController : ControllerBase
{
    private readonly IService _service;

public ExampleController(IService service)
    {
        _service = service;
    }

[HttpGet]
    public ActionResult<Distance> Get()
    {
        return _service. GetDistance();
    }
}

How is this supposed to be written with primary constructors? Should it be like this?

public class ExampleController(IService _service) : ControllerBase

This looks kind of bizarre. Or should we do this?

public class ExampleController(IService service) : ControllerBase
{
    private readonly IService _service = service;

In this case, we still have a private field service that looks like a local variable and is usable anywhere in the type.

It seems like primary constructors were designed only for people who prefer camelCase for local fields and goes against what's defined in the C# coding style conventions.

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Original Comments

Feedback Bot on 10/12/2023, 08:02 PM:

(private comment, text removed)

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Original Solutions

(no solutions)

[sharwell]

Or should we do this?

public class ExampleController(IService service) : ControllerBase
{
    private readonly IService _service = service;

This is the approach I would use.

In this case, we still have a private field service that looks like a local variable and is usable anywhere in the type.

It's my understanding that the compiler will warn if you have service assigned to a field and also try to use it elsewhere. If this is the case, it would make sense for us to hide service from completion lists in cases where using it would produce a warning.

[CyrusNajmabadi]

The guidance is:

The parameters should be named using the naming style for parameters (pascalCased) .

They are not fields and should be named as a fields.

If you do not like referencing the parameters in members of your type, and which to instead reference fields, then it should be assigned to a field (which then follows your field naming-style).