[Boost-users] Re: Mpl problem

From: Arkadiy Vertleyb (vertleyb_at_[hidden])
Date: 2004-07-19 19:50:35

"Delfin Rojas" <drojas_at_[hidden]> wrote

> I am having a problem with the mpl library and I wonder if someone could
> help me with it. Basically I am trying to get a joint_view of two
> mpl::vector types and I get an error message on mpl/clear.hpp saying
>
> clear_traits< Tag >
>         ::template algorithm< Sequence >
>
> base class undefined.
>
> I tried including several of the mpl hpp files, the ones that seemed could
> have something to do with this problem but that didn't help. I also get a
> similar problem trying to use mpl::push_back. In this case I get
>
> push_back_traits< Tag >
>         ::template algorithm< Sequence,T >
>
> Base class undefined.
>
> On the other hand mpl::push_front and mpl::insert compile beautifully.

The error messages you are getting basically say:

"This algorithm is undefined for this type of sequence."

I never used joint_view, but the push_back is currently not defined for the
mpl::vector.  AFAIK, this is going to be corrected in the next version of
Boost (which is currently being put together).

Also, if you are trying to use push_back in combination with, say, fold,
this can be replaced with push_front in combination with fold_backward.

HTH,

Arkadiy