Re: [boost] Phoenix v3 review

Subject: Re: [boost] Phoenix v3 review
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2011-02-25 08:38:43

On 25/02/2011 14:13, Thomas Heller wrote:

>> It would be nice to have a tool like Proto but that was extended to deal
>> with more C++ language constructs. Even if the syntax to call them requires
>> transforming those constructs to expressions with a DSEL of its own, at
>> least there can be a canonic way to do so.
>
> This already exists inside proto, there are basic language constructs
> and it is easily extensible (through proto transforms).

There is no proto::if_, proto::while_ etc.

The way I see it, Phoenix could provide the canonical way to represent 
statements in Proto-based DSELs.

> You can hook up your DSEL into phoenix by extending meta_grammar and
> default_actions.
> Maybe a small example in the documentation would be helpful to explain
> how it really works ...

Since I don't see how that is possible with the current design, I would 
appreciate an example indeed.

default_actions can only be specialized per node tag, not per domain. 
And I don't want to have to duplicate all the Proto node tags for my own 
DSEL like Phoenix does.

I also don't see why the grammar should be affected. It's purely an 
evaluation thing, the Phoenix language itself should not be affected.

> Preprocessed phoenix still needs to resolve all the operator overloads.
> The other points you mentioned will be reworked.

AFAIK, overload resolution is constant-time on all compilers. The 
compile-time slowdown should only come from parsing a larger amount of code.