[Boost-users] analogy to mem_fun_ref to member variables

From: Chris Goller (cgoller_at_[hidden])
Date: 2005-01-26 19:21:43

I have a struct that contains two values.

struct box
{
    double width;
    double length;
}

vector<box> boxes;

I want to accumlate all the widths of the boxes.  The only solution I've 
found is to create a member function get_width that
will return the width for use in mem_fun_ref

eg:

accumulate(make_transform_iterator(boxes.begin(), 
mem_fun_ref(&boxes::get_width)),
make_transform_iterator(boxes.end(), mem_fun_ref(&boxes::get_width)),
0.0,
plus<double>()));

Is there a boost way of not using mem_fun_ref, but rather returns the 
public member variable.  Something that could
be named mem_var_ref that would look like this:

accumulate(make_transform_iterator(boxes.begin(), 
mem_var_ref(&boxes::width)),
make_transform_iterator(boxes.end(), mem_fun_ref(&boxes::width)),
0.0,
plus<double>()));

This way I wouldn't need to add extra get logic to a structure that 
doesn't really need it othewise.

Thanks,

Chris