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Re: Request för std::vector and possibly others: minimal initalization

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Am 29.03.2012 21:28, schrieb Pedro Lamarão:
>
> Em sexta-feira, 23 de março de 2012 21h11min22s UTC-3, Kevin McCarty  escreveu:
>
>>  Case 1)  Interfacing with old (C?) code that will initialize a
>>  contiguous block of memory in-place.  One can't always expect that
>>  existing code can be rewritten to take a vector and call push_back or
>>  emplace_back on it.
>>
>>  E.g., supposing the existence of something called std::no_initialize
>>  (whatever that might be)
>>
>>  // some old 3rd-party library function; maybe it calls fread()?
>>  extern "C" initialize_mem(size_t sz, int * mem);
>>
>>  vector<int>    ints(42, std::no_initialize);
>>  initialize_mem(ints.size(), ints.data());
>
>
> In the OP's use case, there is a known amount of "results" for which space must be allocated.
>
> And it is desired to have space allocated, but no constructors run on it.
>
> Isn't uninitialized-land where operator new and std::allocator live? Why not go there?


Yes, this is certainly possible. Just provide an allocator, where
construct (and presumably also destroy) is basically a no-op. I
certainly would not recommend this technique generally, because it
requires a cool head and a stable nervous system ;-)

Greetings from Bremen,

Daniel Krügler



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Request för std::vector and possibly others: minimal initalization henrikv <henrik.vallgren@stream-space.com> - 2012-03-19 23:35 -0700
  Re: Request för std::vector and possibly others: minimal initalization Francis Glassborow<francis.glassborow@btinternet.com> - 2012-03-21 11:35 -0700
    Re: Request för std::vector and possibly others: minimal initalization henrikv<henrik.vallgren@stream-space.com> - 2012-03-23 17:09 -0700
      Re: Request för std::vector and possibly others: minimal initalization Daniel Krügler <daniel.kruegler@googlemail.com> - 2012-03-24 19:25 -0700
      Re: Request för std::vector and possibly others: minimal initalization Francis Glassborow <francis.glassborow@btinternet.com> - 2012-03-24 19:28 -0700
  Re: Request för std::vector and possibly others: minimal initalization Jason McKesson<jmckesson@gmail.com> - 2012-03-21 11:35 -0700
    Re: Request för std::vector and possibly others: minimal initalization henrikv<henrik.vallgren@stream-space.com> - 2012-03-23 17:10 -0700
      Re: Request för std::vector and possibly others: minimal initalization Jason McKesson<jmckesson@gmail.com> - 2012-03-24 17:55 -0700
      Re: Request for std::vector and possibly others: mi brangdon@cix.compulink.co.uk (Dave Harris) - 2012-03-24 19:24 -0700
      Re: Re: Request för std::vector and possibly others: minimal initalization jgk@panix.com (Joe keane) - 2012-03-27 12:10 -0700
    Re: Request för std::vector and possibly others: minimal initalization Kevin McCarty<kmccarty@gmail.com> - 2012-03-23 17:11 -0700
      Re: Request för std::vector and possibly others:   minimal initalization Miles Bader<miles@gnu.org> - 2012-03-24 17:55 -0700
        Re: Request för std::vector and possibly others: minimal initalization henrikv <henrik.vallgren@stream-space.com> - 2012-03-25 23:14 -0700
      Re: Request för std::vector and possibly others: minimal initalization Jason McKesson <jmckesson@gmail.com> - 2012-03-24 19:27 -0700
      Re: Request för std::vector and possibly others: minimal initalization Pedro Lamarão<pedro.lamarao@gmail.com> - 2012-03-29 12:28 -0700
        Re: Request för std::vector and possibly others: minimal initalization Daniel Krügler <daniel.kruegler@googlemail.com> - 2012-03-29 13:17 -0700

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