Re: [boost] [Review] Quantitative units - compile time vs runtime

From: Steven Watanabe (steven_at_[hidden])
Date: 2007-03-28 12:40:05

AMDG

Michael Fawcett <michael.fawcett <at> gmail.com> writes:

> 
> On 3/28/07, Steven Watanabe <steven <at> providere-consulting.com> wrote:
> >
> > Here is how I would do it:
> >
> > quantity<SI::length> on_dialog_ok()
> > {
> >    double conversion = combo.selected_item().data();
> >    double value = entry.value().as_double();
> >    return quantity<SI::length>::from_value(conversion * value);
> > }
> 
> There may be some confusion (again) on my part as to what
> combo.selected_item.data() is returning, and how it's useful to the
> quantity directly.  I was assuming from Noah's post that it was either
> the integer of the currently selected item in the combo box, or the
> string of the currently selected item in the combo box.  I can see how
> both of those could be immediately useful to the run-time quantity.
> It would either know that the number, say 5, mapped to feet, or it
> would be passed "feet".
> 
> What does your version do exactly?  What is
> combo.selected_item().data() returning, why is it a double, and how
> does from_value use it?
> 
> --Michael Fawcett

The confusion could be on my part.  I was thinking
that the combo box would allow arbitrary data to
be associated with the each item.  If this is not
the case then you need either a map or a switch
statement regardless of whether the units are compile
time or runtime.

In Christ,
Steven Watanabe