Re: [libstdc++ PATH] tr1::bind support

[Paolo Carlini <pcarlini at suse dot de>]

Benjamin Kosnik wrote:

> > What can we do? For one, we can scale back to 10 parameters across the 
> > board. It's the minimum requirement, and although I'd like more 
> > parameters it just takes too long to compile. But, we're still 3 times 
> > slower than the Boost equivalents. We can try to reduce the header 
> > dependencies a bit (for instance, <tr1/functional> ends up including 
> > <string>, which includes <algorithm>, etc.) and factor out the core 
> > parts of <tr1/functional> that <tr1/tuple> needs, so that it doesn't 
> > incur all of that overhead. The long-term solution is probably 
> > something like variadic templates, but that's a big undertaking for a 
> > potentially esoteric feature that still hasn't been completely defined 
> > :)
> >    
> Thanks for the analysis. I think having the machinery to do more than 10
> parameters, but only actually doing 10 parameters by default is fine.
> For string, you may want to try using <bits/stringfwd.h> if you can get
> away with it.
>  
Indeed, this morning, I woke up with a tought in mind: maybe, if there is a
quadratic behavior of sort around, scaling down to 10 parameters could help
a lot!

Thanks a lot Doug and Chris from me too, both for the analysis and the work.

> I don't want to belabor this point (but perhaps have already done so),
> but I think experimenting with designs such as tuple et. al that
> implicitly require variadic templates really necessitate some kind of
> experimental compiler support.
>  
Yes. In my opinion, we should really start investigating that. Zack 
mentioned
variadic templates and we are so lucky to have Doug as contributor: 
would the
C++ front-end maintainers favor an experimental implementation of variadic
templates? In principle, I mean, we are doing (high quality ;) 
science-fiction,
here...

Paolo.