out-of-line and arch-specific random_device

[Paolo Carlini]

Hi again,

Marc Glisse <marc.glisse@inria.fr> ha scritto:

>On Mon, 27 Aug 2012, Ulrich Drepper wrote:
>
>> This is done in the attached patch.  It's rather ugly because of the
>> business with the TR1 support.  Is this really still needed?  Can't
>we
>> remove that?  It really makes not much sense for a random_device to
>be
>> predictable.
>
>Er, I haven't read the context, but for simulations physicists usually
>require that random generators can be repeated, so 2 simulations with
>the
>same seed give the same results. But that may not be what you meant
>with
>predictable.

Again, without context, I think this is not the point: random_device is meant to be just a simple high level wrapper around things like dev/random, inspired by facilities like dev/random on unix-like OSes. The brutal "fall back" we have now in place wouldn't be useful anyway for the uses Marc is talking about, because there is no way to provide a seed. That said, I can't check right now C++11 about random_device, I suppose Uli has already ;)

Paolo