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

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On Friday, March 23, 2012 5:10:25 PM UTC-7, henrikv wrote:
>  On 21 mar, 19:35, Jason McKesson<jmckes...@gmail.com>   wrote:
>  >   This looks more like an improper use of `std::vector` than anything that should be added to the specification.
>
>  IMO, telling the vector which constructor to use isn't "improper use".
>  I'm trying to achieve "minimal but proper initialization", so a class
>  containing something like a std::string would require that member to
>  be properly initialized. I can do the same thing today, all that's
>  required is a default constructor that doesn't touch anything that's
>  not required:
>
>  struct NoInitDummy
>  {
>     NoInitDummy() {}
>
>     // Make this behave like a Dummy using conversion operators etc
>     int a;
>  };

How "minimal" do you want? `std::vector::resize(size_t n)` will value-initialize each element. Why do you need it to be *default* initialized?

>  >   All you need to do is use `std::vector::reserve` to allocate as much space as you plan to use. Then use `emplace_back` to construct each addition to the `vector` in-place.
>
>  Using reserve+emplace_back isn't a good idea. I'm thinking *parallel*
>  loop here, so neither order, nor race conditions can be predicted.

I didn't say to use `emplace_back` as part of the parallel loop. I meant that you would do that to *initialize* the `vector`, using exactly the constructor you want.


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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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