[Boost-users] Re: Using MPL to write is_derived_from_std_basic_ostream

"Jonathan Turkanis" writes:

"Angus Leeming" wrote in message news:ch7h3d$466$1@sea.gmane.org...

...

I'm trying to ascertain whether a given class is, or is derived from, std::basic_ostream, but I've ground to a halt.

I've attached a somewhat improved version inspired by your attempt. (Thanks!) It only works on compilers which support has_xxx, but it should handle the case of private inheritance now, by delegating to is_base_and_derived.

Note that with the current cvs it should not be necessary to write

mpl::and_< mpl::bool_, ...

You can simply say

mpl::and_< has_char_type<U>, ...

It's hard for me to understand why you would need has_xxx for this purpose, or how you would use it. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com