Re: [Boost-users] boost:array lacks a statically-checked get()

From: Benoit Hudson (benoit.hudson_at_[hidden])
Date: 2007-06-05 15:41:06

On 6/4/07, Chris Weed <chrisweed_at_[hidden]> wrote:
> On 6/3/07, Benoit Hudson <benoit.hudson_at_[hidden]> wrote:
> > Reading the archives, I see that the idea of adding a
> >   template <unsigned i> T get();
> > function to boost::array has been somewhat summarily rejected as unnecessary:
> >   http://lists.boost.org/boost-users/2005/08/12983.php
> > et seq.
> >
> > And yet I'm finding myself wanting it repeatedly.  Here are three
> > places I've seen it crop up:
> >
>
> Isn't this functionality available using the boost::fusion extension
> for array? You might want to take a look at boost::fusion.
> Chris

Doesn't appear to.  The following compiles against CVS of 5 minutes
ago, without error:
#include <boost/array.hpp>
#include <boost/fusion/sequence/adapted.hpp>
#include <boost/fusion/sequence/intrinsic.hpp>

boost::array<int, 3> arr = {{ 1, 2, 3}};

int x() {
  // arr[4]
  return boost::fusion::at_c<4>(arr);
}

It compiles down to a call to __assert_fail, which is the same
behaviour as just using arr[4].

-- Benoît