[boost] Re: call_traits aka parameter_traits

From: Beman Dawes (beman_at_[hidden])
Date: 1999-11-29 10:23:58

At 04:57 PM 11/28/99 -0500, Howard Hinnant wrote:
>I find it a little confusing that:
>
>single<UDT>        constructing @unnamed@::UDT by-reference
>single<UDT&>       constructing @unnamed@::UDT by-value
>single<const UDT&> constructing @unnamed@::UDT by-value
>
>I can see the logic, but my knee jerk reaction is that the last two
are 
>passed by reference, not by value.

Unless I am misunderstanding you, that would cause a reference to a
reference, which is not allowed by the language rules.  That was the
case that caused Steve Cleary to develop the empty_member constructor
argument workaround that eventually morphed into call_traits.

--Beman