Re: [boost] [proto] Looong compile times and other issues

Subject: Re: [boost] [proto] Looong compile times and other issues
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2011-09-12 07:36:23

On 12/09/2011 13:10, John Maddock wrote:

> It's not: the issue is that a proto-ized type is used as an argument to
> template functions, so you get quite a deep instantiation tree even
> before the proto-expressions start to get instantiated. That said I
> don't have any issues instantiating those functions with mpfr_class
> (http://math.berkeley.edu/~wilken/code/gmpfrxx/) - which uses it's own
> (admittedly fairly simple) expression-template code.

You could directly use your own backend with the associated evaluation 
functions that don't require any expression templates.

I don't really see what expression templates bring to your big_number 
classes.
The only use I see for that kind of thing is recognizing certain 
patterns of operators to call a better primitive. But in the internals 
you know what the patterns are, and you can optimize them by hand.

Otherwise, I gave a cursory look at your code, and it doesn't seem to be 
making good use of Proto, especially in the file big_number_base.hpp

The whole expression_type thing seems unnecessary and the 
assign_and_eval_imp look like badly-written (and slow) grammars.