Re: That depends... (Was: Regarding assignment to struct)

On 2025-05-05, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:

On 03.05.2025 07:11, Kaz Kylheku wrote:

 
Expanding on this point, C++ goes to town with pass-by-value interfaces
involving objects. For instance the std::basic_string template allows
C++ programs to treat dynamic strings as just values to be tossed
around:
 
   std::string path_combine(std::string dir, std::string name)
   {
      return dir + "/" + name;
   }

>
Hmm.. - my C++ days were long ago but I seem to recall that the
suggestion for passing non-trivial objects by-value was that they
should instead be passed by 'const &' (as a "quasi-by-value") for
performance reasons.

Right; but we don't have to.

I was going to add something else, and started exploring the
generated code for simple functions that just do a + b on
a pair of strings, and trivial functions which call them.

The code generated by GNU C++ with -O3 is so abhorrently verbose,
whether you use const references or go by-value, that I have no appetite
to go into it. 

--
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