[boost] Fusion Question

From: Tom Brinkman (reportbase_at_[hidden])
Date: 2008-07-07 20:01:20

Joel de Guzman,

I'd like to enhance my future boost::layout library proposal
to use your boost::fusion.

Here is a simple example of the boost::layout framework, that uses
boost::gill as the view parameter.

A boost::layout functor takes the following form:

struct layer
{
    template <typename view_t>
    void operator()(view_t& view) {}
};

Examples of layers could be:

fill_layer<> fill;
border_layer<> border;
text_layer<> text;

Lets say I want to combine three layers into a single drawing
operation. Currently, I do it like this:

typedef boost::function<void (view_t&) > layer_t;

layer_t layers[] =
{
        fill_layer<>,
        border_layer<>,
        text_layer<>
}

draw_layers draw(layers,sizeof(layers)/sizeof(layer_t));

boost::gil::rgb8view_t view;
draw(view);

This works fine, but I would like to improve it by using
boost fusion.  Any suggestions or hints to get me started?