Re: [Boost-users] Boost.Range fancify please

Subject: Re: [Boost-users] Boost.Range fancify please
From: OvermindDL1 (overminddl1_at_[hidden])
Date: 2009-12-27 00:45:24

On Sat, Dec 26, 2009 at 8:33 PM, anony <janezz55_at_[hidden]> wrote:
> I have this variable definition:
>
> float vertices[][3] = {
> Â {-1, -1, Â 1}, {1, -1, Â 1}, {1, 1, Â 1}, {-1, 1, Â 1},
> Â {-1, -1, -1}, {1, -1, -1}, {1, 1, -1}, {-1, 1, -1}
> Â };
>
> I want to scale all elements of vertices, by some constant, for now I do
> it like this:
>
> BOOST_FOREACH(float& f, boost::make_iterator_range(
> Â boost::begin(vertices[0]), boost::end(vertices[7])))
> {
> Â f *= scale;
> }

Are you sure that is correct, you are only multiplying the first 7
floats (out of 8*3=24)...

On Sat, Dec 26, 2009 at 8:33 PM, anony <janezz55_at_[hidden]> wrote:
> But maybe something more beautiful could be done with Boost.Range?

Actually you could make it more 'beautiful' (as in shorter code) using
fusion+phoenix if it really is a constant sized array like you have.

This is probably not correct, but I am at work right now so cannot check:

using namespace boost::fusion; using namespace boost::phoenix; using
boost::array;

array<array<float,3>,8> vertices = {
  {-1, -1,  1}, {1, -1,  1}, {1, 1,  1}, {-1, 1,  1},
  {-1, -1, -1}, {1, -1, -1}, {1, 1, -1}, {-1, 1, -1}
  };

for_each(vertices,arg0*=val(scale));  // one line of code

Else, if it is not a static size, then yeah, do what Eric said, even
then his way is short enough that you may as well use it regardless.