Ping... anyone? On 6/9/07, Stjepan Rajko <stipe@asu.edu> wrote:

Hello,

I've started to use fusion for the signal network gsoc project, and am really amazed with how much it simplified the prototype code (it brought down the need for preprocessing+file iteration to a bare minimum). Thanks for such a great library!

I recently ran into a problem, though, and am wondering if someone could help me out. I have a need to do something along the lines of the following:

boost::fusion::vector<int> a; boost::fusion::vector<int &> b(a); // first element of b refers to the first element of a

Using fusion from CVS HEAD, this doesn't work because all of the related constructors take a const & argument. A similar use case (but not exactly what I need) does work:

boost::fusion::vector<int> a; boost::fusion::vector<const int &> b(a);

as does this: (but i'd like to avoid this approach because in my exact case the size of the vectors varies)

boost::fusion::vector<int> a; boost::fusion::vector<int &> b(boost::fusion::at_c<0>(a));

I tried adding non-const versions of the constructors / helper functions to vector/vector.hpp and vector/vector_n.hpp, and after doing so the use case I need works OK.

Unless there is an alternative way of doing what I'm trying to do, would it be possible to add in the non-const versions of the constructors? I don't mind producing the patches if someone points me to all the places where the non-const constructors should be added to make the addition consistent, as well as to any non-obvious things that would also need to be done (keeping in mind that currently my scope of "obvious" appears to be pretty limited :-))

Thanks for your help,

Stjepan