Re: [Boost-users] Help with (possibly MPL) pattern for a viewer that may contain a copy of statically allocated data

Subject: Re: [Boost-users] Help with (possibly MPL) pattern for a viewer that may contain a copy of statically allocated data
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2009-01-29 12:23:41

AMDG

jesseperla wrote:
> A followup if anyone else is using this code:
>
> Steven:  Your code worked beautifully, but it turned out that I also
> needed an assignment operator (which fails due to the const on the
> ref).  For now, I did the following:
> typedef boost::add_reference<boost::add_const<boost::mpl::_1> > >
> const_reference_policy;
> typedef boost::add_reference<<boost::mpl::_1 > > reference_policy;
>
> Things *kind of* work now for the default assignment operator
> generated by the compiler.  I can now create a new item and then use
> the copy assignment(if they have the same storage policy).  Things
> like...
>   regular_grid <2,3> interp( f_values); //The default is the new non-
> const reference_policy.
>   regular_grid <2,3> interp3 = interp; //Works!  Also works for the
> copy_policy
>   interp3 = interp; //Fails!  Also fails for the copy_policy
>
> Lower priority for me, but assignment will only work for 2 grids of
> type ref or 2 of type value.  What is the best way to write the
> assignment operator to allow assignment between the different policy
> types? (combinations except assignment to a const_reference_policy of
> course)
>   

template<int M1, int N1, class S>
friend class regular_grid;
regular_grid& operator=(const regular_grid& other) { axis_ = other.axis_ };
template<class S>
regular_grid& operator=(const regular_grid<M, N, S>& other) { axis_ = 
other.axis_ };

In Christ,
Steven Watanabe