on Thu Oct 06 2011, "Peter Dimov" <pdimov-AT-pdimov.com> wrote:
Dave Abrahams wrote:
none_of_equal could be written in the same style. But you seem to want something different than that; I guess that you want to add a requirement on the type of the value, right?
No, I want to avoid a requirement by encoding it into the function signature.
How would you do that? The function signature can't encode the requirement that *i == value should work, or...
It encodes the requirement that the two things we're comparing have the same type.
You're missing that == should *mean* something.
... mean something, or...
You're not even requiring it to be symmetric.
... that it's equivalent to value == *i. You still need to add these requirements. Sure, you can call them "value_type shall be EqualityComparable" and even then, you'll have to spell "*i == value" when describing the semantics, either directly or by saying something like "finds the first *i that equals value",
Yes!
which, if we're being really pedantic, doesn't really specify anything, because "x equals y" is not defined anywhere.
Only if we're being standards-pedantic. If we're being mathematical and using commonly accepted definitions of terms, it is perfectly well-specified.
Bottom line, you'll add a conversion and a bunch of unnecessary requirements and end up with the exact same specification as before, namely, returns the first i for which *i == value.
I claim that "finds the first element in [first, last) that equals value" is a better way to say it. -- Dave Abrahams BoostPro Computing http://www.boostpro.com