Proposal: Refactorable strings and comments

[p-e-timoshenko]

The “nameof” operator becomes a string constant during compilation instead of execute code to obtain name of code element by using tree expressions or reflection methods. So the introduced operator is a big advantage of C#, but it's also a disadvantage too. The possibilities of JIT-compiler isn't involved. It doesn't allow to predict the dynamic code changes and to substitute the name rightly. Besides, there is no opportunity to transform part of a code to string by principle “as is” to track its further changes: “System.Math.PI”, “Type Property” or “Type Namespace.Class.Method(Type arg0, Type arg1, ...)”. Functional style of the operator is perhaps doubtful. I'd want to ask a question: what type of argument? But the question disappears, because already there are similar methods like “typeof”. In addition, after compilation the method-like operator is replaced by string. Perhaps, it would be more natural to expand functionality of the string interpolation for strict and literally transform parts of code to string with validating it at compile time:

$"'\@{MyNamespace.SomType}', '\@{SomType arg0}', '\@{arr[index]}'." 
//'MyNamespace.SomeType', 'SomType arg0', 'arr[index]'.
$"'\@{MyNamespace.{SomeType}}', '\@{{SomType} arg0}', '\@{{public }int {Prop}}'." 
//'SomeType', 'SomeType', 'public Prop'. The braces used for the selective conversion

The probability of that the “nameof” operator will be a part of interpolated string is very high. The offered syntax of refactorable strings may be applied conveniently in the comments:

// This comment contains the name of @{MyNamespace.SomeType} type that
// sensible to the code refactoring.

You could see my article "Talking About “nameof” Operator" containing a clear description of the proposal.

[alrz]

Related to #85 and #7655

/// This comment contains the name of `MyNamespace.SomeType` type that
/// sensible to the code refactoring

[gafter]

We are now taking language feature discussion in other repositories:

• https://github.com/dotnet/csharplang for C# specific issues
• https://github.com/dotnet/vblang for VB-specific features
• https://github.com/dotnet/csharplang for features that affect both languages

Features that are under active design or development, or which are "championed" by someone on the language design team, have already been moved either as issues or as checked-in design documents. For example, the proposal in this repo "Proposal: Partial interface implementation a.k.a. Traits" (issue 16139 and a few other issues that request the same thing) are now tracked by the language team at issue 52 in https://github.com/dotnet/csharplang/issues, and there is a draft spec at https://github.com/dotnet/csharplang/blob/master/proposals/default-interface-methods.md and further discussion at issue 288 in https://github.com/dotnet/csharplang/issues. Prototyping of the compiler portion of language features is still tracked here; see, for example, https://github.com/dotnet/roslyn/tree/features/DefaultInterfaceImplementation and issue 17952.

In order to facilitate that transition, we have started closing language design discussions from the roslyn repo with a note briefly explaining why. When we are aware of an existing discussion for the feature already in the new repo, we are adding a link to that. But we're not adding new issues to the new repos for existing discussions in this repo that the language design team does not currently envision taking on. Our intent is to eventually close the language design issues in the Roslyn repo and encourage discussion in one of the new repos instead.

Our intent is not to shut down discussion on language design - you can still continue discussion on the closed issues if you want - but rather we would like to encourage people to move discussion to where we are more likely to be paying attention (the new repo), or to abandon discussions that are no longer of interest to you.

If you happen to notice that one of the closed issues has a relevant issue in the new repo, and we have not added a link to the new issue, we would appreciate you providing a link from the old to the new discussion. That way people who are still interested in the discussion can start paying attention to the new issue.

Also, we'd welcome any ideas you might have on how we could better manage the transition. Comments and discussion about closing and/or moving issues should be directed to #18002. Comments and discussion about this issue can take place here or on an issue in the relevant repo.

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I am not moving this particular issue because I don't have confidence that the LDM would likely consider doing this.