Re: [Boost-users] [fusion] Stateful unary functor for for_each loop

From: Joel de Guzman (joel_at_[hidden])
Date: 2007-03-19 20:02:07

Eric Niebler wrote:
> Tobias Schwinger wrote:
>> Christian Henning wrote:
>>> Hi there, is it possible to have a stateful functor object when using
>>> fusion::for_each() loop.
>>>
>>> I would like to to the following:
>>>
>> <snip code>
>>
>> for_each takes the function object by reference to const, so you have to 
>> const qualify operator() and make the data members mutable so you can 
>> change them anyway.
> 
> 
> IMO, this is a bug in Fusion. There should be an overload of for_each 
> that takes a function object by non-const reference. Stateful predicates 
> should be supported, and Fusion should be explicit about where and when 
> predicates are copied, so that the state doesn't get messed up.

I agree. This is one of the todo items. Noted and added in the queue.

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