From: Douglas Gregor (gregod_at_[hidden])
Date: 2002-11-11 09:02:40
On Monday 11 November 2002 04:56 am, Aleksey Gurtovoy wrote:
[snip my limited example]
> Hmm, interesting, so if this actually worked, we would be happy:
[snip nifty-looking is_callable implementation]
Well, you need to do some trickery to make it work when R=void, but otherwise
I think we would be _very_ happy if this worked. Is there a tweak to the core
language that would guarantee such a thing?
> > The reason I mention is_instantiable instead of __is_well_formed
> > is that is_instantiable can keep a class template interface, whereas
> > __is_well_formed would require a new grammar production.
> From http://aspn.activestate.com/ASPN/Mail/Message/1412095 I've got an
> impression that implementors are not too concerned about it.
> After all, '__is_well_formed' might be as easy to implement as this:
> void process_is_well_formed( args )
> process_sizeof( args );
> args.expression_result = true;
> catch (compiler_error const& )
> args.expression_result = false;
At one time in GCC, checking for compilability was as easy as:
// instantiate the thing you want to check
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