Re: [boost] [proto] transform for flattening an expression - how?

From: Eric Niebler (eric_at_[hidden])
Date: 2008-03-20 17:23:11

Steven Watanabe wrote:
> Eric Niebler wrote:
>> One of the big sources of slow-down is the operator() overloads on
>>  expr<> ... there are N specializations of expr<>, and each one has
>> N overloads of operator(). That's O(N^2) growth. With a variadic 
>> operator(), I should be able to knock that down to O(N).
> 
> In that case, since Marcus wants a larger arity for automatically 
> generated exprs rather than ones created using operators, couldn't
> you set the max arity for the function call overloads separately from
> the max expr arity?  How are compile times if you keep the function
> call arity fixed at 5?

A quick test shows this to be a very good way to keep compile times 
under control.

Max arity	Max Function call arity		Compile time (sec)
------------------------------------------------------------------
40		40				24.1
40		5				14.0

Thanks for the suggestion.

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com