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Re: [std-proposals] Dummy names for dummy objects

From: Chris Ryan <chrisr98008_at_[hidden]>
Date: Fri, 16 Jun 2023 15:25:50 +0300
P2169 has been actively discussed (yesterday & today, literally minutes
ago) and bouncing back & forth between EWG(evolution) & CWG(core) adjusting
the usage under special cases. Things are looking good. It is potentially
likely (no guarantees) that _ (an underscore) will be an unnamed
placeholder in C++26 usable in many/most places you would normally have an
identifier including structured bindings.

Chiris++;

On Sat, Jun 10, 2023 at 5:34 PM Sebastian Wittmeier via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> See P2169 A Nice Placeholder With No Name
>
>
>
> https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2169r3.pdf
>
> https://github.com/cplusplus/papers/issues/878
>
>
> -----Urspr√ľngliche Nachricht-----
> *Von:* Frederick Virchanza Gotham via Std-Proposals <
> std-proposals_at_[hidden]>
> *Gesendet:* Sa 10.06.2023 16:27
> *Betreff:* [std-proposals] Dummy names for dummy objects
> *An:* std-proposals <std-proposals_at_[hidden]>;
> *CC:* Frederick Virchanza Gotham <cauldwell.thomas_at_[hidden]>;
> Sometimes I have code like this:
>
> void Func(void)
> {
> OnScopeExit dummy( [](){ ::close(global_fd); } );
>
> // Do more stuff here
> }
>
> If I later amend this function so that further down there's another
> 'OnScopeExit', then I have to name the second one "dummy1", and the
> third one "dummy2" and so on.
>
> For the sake of making it easier to patch source files, I propose that
> we can give an object a dummy name as follows:
>
> void Func(void)
> {
> OnScopeExit __dummy( [](){ /* Do Something */ } );
>
> // Do more stuff here
>
> OnScopeExit __dummy( [](){ /* Do Something */ } );
>
> // Do more stuff here
>
> OnScopeExit __dummy( [](){ /* Do Something */ } );
> }
>
> These objects don't have a name clash. If you try to access an object
> by the name '__dummy', it accesses the most recently defined dummy
> object:
>
> void Func(void)
> {
> OnScopeExit __dummy( [](){ /* Do Something */ } );
>
> // Do more stuff here
> _dummy.SomeMethod(); // refers to the object defined 3 lines above
>
> OnScopeExit __dummy( [](){ /* Do Something */ } );
>
> // Do more stuff here
> _dummy.SomeMethod(); // refers to the object defined 3 lines above
>
> OnScopeExit __dummy( [](){ /* Do Something */ } );
> }
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>
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Received on 2023-06-16 12:26:05