Re: [boost] review request: addition to type_traits library ofis_less_comparable<T, U> and others

Subject: Re: [boost] review request: addition to type_traits library ofis_less_comparable<T, U> and others
From: Jeffrey Hellrung (jhellrung_at_[hidden])
Date: 2009-12-07 12:13:39

John Maddock wrote:
> has_operator_less<T, R = bool>

Maybe should be has_operator_less< T, U = T, R = bool > ?  (one step 
further than frederic's suggestion, and in line with your 
has_operator_plus suggestions below)

> So how about: has_operator_plus<T, U = T, R = dont_care> ?
> 
> Hard to decide what R should default to in this case, I'm tempted by the 
> "permissive" case of dont_care because it will do the right thing in 
> more mixed arithmetic cases, but the alternative would be to default R 
> to T I guess.

Default R = common_type<T,U>::type (the common_type from another thread) ?

And (somewhat off-topic) I think the default common_type should *not* 
use decltype (i.e., Boost.Typeof) if not available, which would limit 
common_type<T,U>::type to be either T or U most of the time, unless 
specialized.

Also, why couldn't void take the place of dont_care ?

> Just my 2c, John.

And that's mine.

- Jeff