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Subject: Re: [boost] [utility] new auto_buffer class --- RFC
From: Thorsten Ottosen (thorsten.ottosen_at_[hidden])
Date: 2009-03-14 04:47:41

David Abrahams skrev:
> On Mar 6, 2009, at 2:30 AM, Thorsten Ottosen wrote:
>>>> For the
>>>> operations that they have in common, it is almost a drop-in
>>>> replacement.
>>>> I say almost, because this class is really about speed, and often don't
>>>> allow overlapping ranges, assignment to *this etc. The exception-safety
>>>> guarantees might also be weaker if it hurts performance.
>>> I think anything that's an "almost" needs an explicit rationale. I
>>> really don't, for example, see why the self-assignment check is worth
>>> omitting.
>> The rationale would be simplicity, speed and less generated code.

Remark: the comment is more general, and also pertains to non-e.g. not
allowing overlapping ranges.

> Have you measured the speed/space difference and found it to be
> significant in any real application?
> A class that attempts to provide value semantics but doesn't support x =
> x is putting a big hole in the system of equational reasoning.
> Justifying that (to me) would take some pretty heavy proof.

I have not really seen code that exhibits x = x. I've seen lot's of
discussion (e.g. Sutter & Meyers). Does anybody write such code?


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