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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

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

> Just my 2c, John.

And that's mine.

- Jeff

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