Re: [Boost-users] binary mpl::transform fails to compile with fusion::vector

Subject: Re: [Boost-users] binary mpl::transform fails to compile with fusion::vector
From: Joel de Guzman (joel_at_[hidden])
Date: 2009-06-17 13:07:33

Mike Tegtmeyer wrote:
> I am hoping someone can point me the in right direction regarding this 
> code snippit failing to compile. My suspicion is that it is a header 
> problem but any help would be appreciated.
> 
> In short, I seem to be missing why the binary form of mpl::transform 
> won't work with fusion::vector. (unary form works just fine).
> 
> The code below just attempts to make a std::pair<> from the contents of 
> two sequences (this is just an example to illustrate the transform 
> problem). If the two sequences are mpl::vectors, everything is fine. If 
> they are fusion::vectors then 'lots of errors'.
> 
> I'm fairly new to both mpl and fusion so I am not ruling out the fact 
> that I have done something stupid.
> 

Trying the code, it seems mpl::(binary)transform is looking for
Seq::tag which is not a requirement for MPL::Forward Sequence
which mpl::transform requires (http://tinyurl.com/l6kcb4).
fusion::vector adheres fully to an MPL::Forward Sequence.

I'm guessing this is an MPL problem, but I may be wrong, so I'll
leave it to the better hands of Aleksey. Aleksey, can you help?

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