Re: Move semantics with literals

From	Andrey Tarasevich <noone@noone.net>
Newsgroups	comp.lang.c++
Subject	Re: Move semantics with literals
Date	2026-04-18 09:46 -0700
Organization	A noiseless patient Spider
Message-ID	<10s0cha$3b4c6$2@dont-email.me> (permalink)
References	<10rlkk9$6hau$1@dont-email.me> <10s0bd5$3b4c6$1@dont-email.me>

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On Sat 4/18/2026 9:27 AM, Andrey Tarasevich wrote:
> Moreover, there's no 
> "move semantics" in C++ language. "Move semantics" is a user-level 
> concept - something you implement yourself in your user-level code. The 
> only thing C++ the language does is provide some low-level primitives to 
> help you do that (e.g. rvalue references). But the above example has no 
> "move semantics".
> 

Of course, the above might be see as a bit self-contradictory. Since I 
myself stated that "move semantics" is a user-level concept, you can 
always claim that your original example is actually "move semantics", 
i.e. it is your user-level vision of it.

After all, for flat types (like `int`) there's not much point in 
implementing any kind of move semantics different from their usual copy 
semantics. And that's what the original version of your function does.

One can also modify it as follows

   int func(int &&a)
   {
     int result = a * 2;
     a = 0;
     return result;
   }

and then document the behavior, stating that the version of move 
semantics implemented by this function zeroes out the original argument 
(or modifies it in some unspecified way). For some reason. That is also 
perfectly fine.

However, keep in mind that this will not even attempt to modify the 
original literal `123`. As I stated in my previous post, a modifiable 
temporary of type `int` will be created as an argument for the call. It 
is that temporary that will get modified. The literal will remain untouched.

-- 
Best regards,
Andrey

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Move semantics with literals boltar@caprica.universe - 2026-04-14 14:57 +0000
  Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 11:01 -0400
    Re: Move semantics with literals wij <wyniijj5@gmail.com> - 2026-04-14 23:04 +0800
    Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 11:10 -0400
      Re: Move semantics with literals David Brown <david.brown@hesbynett.no> - 2026-04-14 17:26 +0200
      Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-14 18:25 +0200
        Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 13:02 -0400
        Re: Move semantics with literals boltar@caprica.universe - 2026-04-15 08:18 +0000
          Re: Move semantics with literals Paavo Helde <eesnimi@osa.pri.ee> - 2026-04-15 12:50 +0300
          Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-15 14:24 +0200
            Re: Move semantics with literals boltar@caprica.universe - 2026-04-15 15:07 +0000
              Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-15 17:49 +0200
              Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-15 17:51 +0200
                Re: Move semantics with literals boltar@caprica.universe - 2026-04-16 08:29 +0000
                Re: Move semantics with literals scott@slp53.sl.home (Scott Lurndal) - 2026-04-16 14:41 +0000
                Re: Move semantics with literals Chris Ahlstrom <OFeem1987@teleworm.us> - 2026-04-18 06:41 -0400
              Re: Move semantics with literals Richard Damon <Richard@Damon-Family.org> - 2026-04-18 12:46 -0400
            Re: Move semantics with literals "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-15 23:08 -0700
              Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-16 09:02 +0200
                Re: Move semantics with literals "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-16 04:39 -0700
    Re: Move semantics with literals boltar@caprica.universe - 2026-04-14 15:10 +0000
      Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 11:15 -0400
      Re: Move semantics with literals scott@slp53.sl.home (Scott Lurndal) - 2026-04-14 17:17 +0000
        Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 13:36 -0400
          Re: Move semantics with literals boltar@caprica.universe - 2026-04-15 08:21 +0000
      Re: Move semantics with literals Andrey Tarasevich <noone@noone.net> - 2026-04-18 10:16 -0700
        Re: Move semantics with literals boltar@caprica.universe - 2026-04-19 08:59 +0000
          Re: Move semantics with literals boltar@caprica.universe - 2026-04-19 09:09 +0000
          Re: Move semantics with literals Andrey Tarasevich <noone@noone.net> - 2026-04-19 12:01 -0700
  Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-14 17:14 +0200
    Re: Move semantics with literals boltar@caprica.universe - 2026-04-14 15:23 +0000
      Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-14 18:23 +0200
  Re: Move semantics with literals Andrey Tarasevich <noone@noone.net> - 2026-04-18 09:27 -0700
    Re: Move semantics with literals Andrey Tarasevich <noone@noone.net> - 2026-04-18 09:46 -0700

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