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
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.
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