Re: [boost] Phoenix v3 review

Subject: Re: [boost] Phoenix v3 review
From: Joel de Guzman (joel_at_[hidden])
Date: 2011-02-25 07:35:43

On 2/25/11 2:24 PM, Thomas Heller wrote:
> On Fri, Feb 25, 2011 at 7:08 AM, Joel Falcou<joel.falcou_at_[hidden]>  wrote:
>> On 25/02/11 03:21, Joel de Guzman wrote:
>>>
>>> :-) Mathias has a point. Let's also discuss this off-list. With Spirit,
>>> I've already begun the migration towards an object free environment,
>>> but that's for terminals --of which proto is known to slow down
>>> compilation when there are lots of terminals. I am not quite sure
>>> about function objects.
>>
>> I want to point you again tomy boostcon 2k10 talk. we showed figure where
>> the old nt2, using instance of function object , resulted in a linear
>> compile time,
>> while having template function using make_expr get us constant compile time.
>>
>> Here the post I made way before on the same issue:
>> http://lists.boost.org/boost-users/2009/02/45591.php
> <snip>
>
> You have a point for proto terminals. A phoenix::function is _not_ a
> proto terminal though.
> here is a sketch of the implementation:
>
> template<typename Func>
> struct function
> {
>      template<typename A0 ... typename AN>
>      typename proto::result_of::make_expr<tag::function, Func, A0, ..., AN>
>      operator()(A0 const&  a0, ..., A1 const&  a1) const
>      {
>             return proto::make_expr<....>(....);
>      }
> };
>
> It already behaves like the proto generator functions you described.
> Maybe the instantiation of a phoenix::function<F>  also add
> significantly to compile time and binary size. These were the numbers
> I was interested in.

Exactly. Phoenix functions are not proto terminals. I agree with
Thomas, I'd like to see the numbers first before jumping to a conclusion.

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