Re: [boost] [mpl][fold.html] apply<op, _1, deref<_2> > correction needed.

Subject: Re: [boost] [mpl][fold.html] apply<op, _1, deref<_2> > correction needed.
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2009-03-11 12:38:08

AMDG

Larry Evans wrote:
> The vault file:
>
>   http://preview.tinyurl.com/cbr9k3
>
> demonstrates the bug.  What's the correct
> value for the ForwardOp arg to iter_fold in
> http://www.boost.org/doc/libs/1_38_0/libs/mpl/doc/refmanual/fold.html?

I'm very confused.  First of all, in the
assertions, you probably want boost::mpl::equal_to
instead of boost::mpl::equal.
Second, I don't see fold or iter_fold at all.
Finally, when you use a lambda expression
inside another lambda expression, you need
to wrap it in protect.

mpl::apply<mpl::apply<op_meta_fun_elem<_1, _2>, _1, mpl::deref<_2> >, 
state0, iter0>::type

is guaranteed to behave strangely, because all the placeholders
will be substituted by the outermost apply.

In Christ,
Steven Watanabe