Re: [boost] [lambda] extension question

From: Joel de Guzman (joel_at_[hidden])
Date: 2005-07-19 12:58:17

Peter Dimov wrote:
> Joel de Guzman wrote:
> 
>>Jaakko Järvi wrote:
>>
>>> Yes, a null_type is passed to sig. This is because the signature
>>> of the zero argument lambda function (in lambda_functor class)
>>> signature is instantiated always, regardless of whether it is
>>> called or not. And there the argument list is just null_type. 
>>> Hence, the return type deduction is not allowed to cause a 
>>> compilation error in the case where the argument tuple to sig is
>>> null_type.
>>
>>FYI, this is a typical problem. Phoenix-2 has fixed this nagging
>>problem.
> 
> 
> How? 

By disabling the nullary operator() when appropriate
(e.g. by computing the minimum arity).

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