Re: [scope] Proposing Boost.Scope

From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2023-03-22 12:25:32

On 3/22/23 14:23, Daniela Engert via Boost wrote:
> Am 22.03.2023 um 11:24 schrieb Andrey Semashev via Boost:
>> [[nodiscard]] is not usable here as there's nothing to apply it to, as
>> we're talking about the scope guard constructor.
> 
> [[nodiscard]] is highly desirable here. You can apply the attribute to
> class types (and thus their constructors) and avoid the (typically
> unwanted) immediate destruction of pr-values. Manager classes should be
> marked [[nodiscard]] by habit.

I didn't know you can apply [[nodiscard]] to classes, but apparently you
can. I suppose, I could mark scope guards with it, but I'm not sure if
limiting the use cases would be desirable. For example, should we
consider the following a wrong use of the scope guard?

  auto foo()
  {
    // do something useful and return the epilogue
    return scope_exit([] { whatever });
  }

  void bar()
  {
    foo(); // do what foo() does, plus the epilogue
    // ...
  }

  void zoo()
  {
    auto epilogue = foo(); // do what foo() does, and delay the epilogue
    // ...
  }