Re: [Boost-users] [review] Fast track formal review of Forward library begins today

From: Joel de Guzman (joel_at_[hidden])
Date: 2007-12-05 00:13:54

David Abrahams wrote:
> on Tue Dec 04 2007, Joel de Guzman <djowel-AT-gmail.com> wrote:
> 
>> John Torjo wrote:
>>
>>>      * What is your evaluation of the design?
>> simple and effective. I'd like to see more tweakable
>> parameters for specific uses. I frequently deal with
>> different number expansions in a case to case basis.
>> For example, is it possible to have arity 3 for function
>> X and arity-5 for function Y? A single number seems
>> wasteful if I'm sure that a certain use needs only a few.
>> Is that possible?
> 
> It generates one template definition.  You could generate a bunch of
> different templates for different uses but I don't see much advantage;
> it would probably slow down compilation overall.

Hmmm... because you'll have different templates instead of one?
But isn't the time of N instantiations of a single class template
equivalent to the the time of instantiation of N different templates?
(assuming same complexity). I really doubt this, without any numbers.

And, even if it was true, I'd think that the exponential nature of
expansion of the arities have a larger effect both with PP and in
overload resolution. Those too should be a significant factor
apart from template instantiations.

Pondering... It would be interesting to see real numbers.

Regards,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net