Re: [boost] [Review:Algorithms] Order of args to clamp

Subject: Re: [boost] [Review:Algorithms] Order of args to clamp
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2011-09-25 09:56:42

Le 24/09/11 22:53, Andrew Sutton a écrit :
>> template<  class T, class L, class U>
>> typename common_type<  T const&, L const&, U const&  >::type
>> clamp(T const&  x, L const&  lower, U const&  upper)
>> { return x<  lower ? lower : upper<  x ? upper : x; }
>>
>> for the use of common_type (assuming it accepts 3 parameters, which I seem
>> to remember it did; if not, just nest); and something like
> Can we please not define algorithms this way? It may be possible, but
> that doesn't mean its a good idea. I don't know how you could possibly
> prove that the algorithm preserves ordering (<) when the algorithm
> includes 5 possibly different types.
>
> Thats not strictly true. I do know how you can prove it preserves
> ordering, but I'm not going to encourage the style.
>
> Define it in terms of a single type and let conversions happen at the call type.
>
>
Hi,

I think that it is reasonable to compare different types. One example is 
chrono::duration. You can compare durations with a different Period.

It would be great if the proposed clamp function could be used also as in

auto res = clamp(val, minutes(30), hours(10));

Other examples can be found in the Unit library.

Best,
Vicente