Re: [boost] Serialisation: Is is_trivial<T> a sufficient precondition to bypass serialisation?

Subject: Re: [boost] Serialisation: Is is_trivial<T> a sufficient precondition to bypass serialisation?
From: Thomas Heller (thom.heller_at_[hidden])
Date: 2015-02-04 15:46:43

Am 04.02.2015 12:54 schrieb "Niall Douglas" <s_sourceforge_at_[hidden]>:
>
> A library user has raised an interesting question at:
>
> https://github.com/BoostGSoC13/boost.afio/commit/ac32ebfceb9a08b133e8c
> d47000d3b4807bc3e42#commitcomment-9574522
>
> Basically, AFIO v1.3 has new pre-serialisation metaprogramming in
> response to Robert's comments on his Incubator about it being too
> hard to serialise and deserialise data with AFIO. AFIO will now
> consume any STL container and will implicitly auto expand to ASIO
> scatter gather buffers any:
>
> 1. Trivial type T
> 2. C array of trivial type T
> 3. STL container of trivial type T, including initializer_list.

So you generate a list of N scatter/gather buffers for a container with the
size of N? That sounds a tad too much. Doesn't that create a immense
overhead for the network interface?

>
> A free function, to_asio_buffers(T), can be specialised by external
> code to extend this with custom ASIO scatter gather buffers
> generation. Note that AFIO explicitly and intentionally expects that
> anyone interested in async file i/o will be doing their serialisation
> and endian conversion far away from AFIO code, so to_asio_buffers(T)
> is really for marking extra types to be treated as implicit auto
> expand.
>
> The user asks the question: Is is_trivial<T> a sufficient
> precondition for this auto expansion to be safe, or should
> is_standard_layout<T> also be required? The user notes that
> is_trivial<T> && is_standard_layout<T> == is_pod<T> which seems a
> little overkill to me.
>
> There is also the possibility that is_trivial<T> is too conservative.
> Some may argue that is_trivially_copyable<T> would be sufficient.
> Thoughts?
>
> Niall
>
> --
> ned Productions Limited Consulting
> http://www.nedproductions.biz/
> http://ie.linkedin.com/in/nialldouglas/
>
>
>
>
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