[Proposal] add a required keywork for properties and perhaps member

[VGib]

In C#, object properties can be initialized using the with keyword or object initializers ({} syntax). For example:

public class A
{
    public string Sample { get; set; }
    public string Sample2 { get; set; }
}

var a = new A
{
    Sample = "test"
};

When properties are mandatory, the preferred approach is to initialize them via a constructor. However, this becomes unwieldy when a class contains many required properties. For instance, a constructor with 10 or more parameters can be difficult to read, maintain, and use effectively.

Proposal
Introduce a required keyword for properties or fields. This keyword enforces that any property marked as required must be initialized:

In the constructor.
Using object initializers ({} syntax).
If a required property is not initialized, this should result in an error (compile time, or execute time ? )
Example

public class A
{
    public mandatory string Sample { get; set; }
    public string Sample2 { get; set; }
}

// Valid: All manadatories properties initialized.
var a = new A { Sample = "test" };

// Error: `Sample` is required but not initialized.
var b = new A();

// Valid: `Sample` initialized via constructor.
var c = new A("test");

Benefits
Improves code readability by reducing constructor complexity and avoid error for models with more than 10 parameters.

Problem
For sample how to deal with reflexion object creation.

var a = (A) Activator.Create(typeof(A))

[HaloFour]

See: https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/required

SharpLab

[VGib]

OK so my apologized i didn't understand that, the documentation should be updated. It's not clear that that can be initiliazed with custom construction.

Regards,

(An example of the warning case may be good)

Vgib

[333fred]

Being perfectly honest, I'm not sure how this first line of that page could be made any clearer:

The required modifier indicates that the field or property it's applied to must be initialized by an object initializer.

[VGib]

i don't know, i always thought that it is a check of all avalaible initializers (avalaible constructors)

[CyrusNajmabadi]

Initializers and constructors are different. Constructors are passed arguments on an argument list like new ... (a, b, c). Initializers assign to properties and fields like new ... { a = 0 }

[VGib]

But this checks if his has been initialized from constructor or the initilizer.

When you speak it's clear, but for me it isn't from english documentation (maybe because i'm not a native english guy).

Anyway i will use required when i need a check in the object initilizer

Regards,