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Subject: Re: [boost] [range] [general] making member functions SFINAE-friendly
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2013-02-18 13:56:10


On 02/18/2013 10:15 AM, Jonathan Wakely wrote:
> On 18 February 2013 18:04, Dave Abrahams wrote:
>>> However, if detecting whether "r.size()" is a valid expression
>>> cannot be done reliably (for example, if we determine that for
>>> iterator_range<I> where I is not random-access it is a valid
>>> expression, but then that static-asserts on us), then we
>>> can't use this approach.
>> Then you can't use this approach (in general).
> Why? What other range-like types provide an size() member that
> appears to be callable but must not be called?

That's irrelevant. The point is that the range
concepts provide no such requirement. It is unsafe
to rely on any behavior which is not intentional and
explicitly documented, /especially/ with generic code.

In Christ,
Steven Watanabe

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