[Proposal]: [Allow Custom Implicit Conversion from Struct to Nullable Struct]

[AX0201]

//I not English.I using GPT write this,but I was serious

Feature Request:

I propose that C# should allow custom implicit conversion from a user-defined struct to its nullable equivalent. This feature would enable developers to define how a struct should be implicitly converted to its nullable form, enhancing the flexibility and expressiveness of the language.

Rationale:

Currently, in C#, primitive types can be implicitly converted to their nullable versions, but user-defined structs do not support this behavior. This inconsistency can lead to more verbose and less readable code when working with nullable structs. By allowing custom implicit conversion, developers can provide a more seamless and intuitive experience when using their custom structs with nullable types.

Proposed Syntax:

Developers should be able to define an implicit conversion operator within their struct that specifies how to convert the struct to its nullable form. Here is an example of how this might look:

csharp
public struct MyStruct
{
public int Value;
// Implicit conversion from MyStruct to MyStruct?
public static implicit operator MyStruct(MyStruct? X)
{
return new MyStruct{ Value=X.Value.Value};
}
}
Benefits:

Improved Code Readability:
Allowing custom implicit conversion would reduce the need for explicit conversions, resulting in cleaner and more readable code.

Consistency with Primitive Types:
This feature would make user-defined structs behave more consistently with primitive types, which already support implicit conversion to their nullable versions.

Enhanced Developer Experience:
Developers would have more control over their types, enabling them to define more intuitive and seamless interactions between their structs and nullable types.

Reduced Boilerplate Code:
The ability to define custom implicit conversions would reduce boilerplate code and make the use of nullable structs more straightforward.

Conclusion:

Allowing custom implicit conversion from user-defined structs to their nullable equivalents would be a valuable addition to the C# language. It would enhance code readability, consistency, and developer experience while reducing the need for verbose and repetitive code. I believe this feature aligns with the language's goals of being expressive, intuitive, and developer-friendly.

I urge the committee to consider this proposal and evaluate its potential benefits for the C# developer community.

Thank you for your consideration.

[333fred]

As per our README, all new proposals need to start as discussions. Converting this over.

[huoyaoyuan]

Implicit conversion from MyStruct to MyStruct? has always been allowed. There's no gap between primitives and user defined structs.

You code is showing conversion in the opposite version, from MyStruct? to MyStruct. This is always disallowed, and there's a shorthand with ?? operator.

[TahirAhmadov]

Yes, there is a language barrier. He's asking to allow defining implicit operator from S? to S, which is currently illegal.

Personally, I think it's an anti-pattern to have operators like that. There may be reasons why it's not even possible, I'm not sure, but even if it was possible, I don't think it would be a good idea.

[CyrusNajmabadi]

Currently, in C#, primitive types can be implicitly converted to their nullable versions, but user-defined structs do not support this behavior

This is definitely not the case. All value types (excluding Nullable<> itself) can be implicitly converted to their nullable version.