Re: [Boost-users] units and existing APIs

Subject: Re: [Boost-users] units and existing APIs
From: Matthias Schabel (boost_at_[hidden])
Date: 2008-11-03 17:48:10

> I would like to use boost::units in a new application that must  
> interface to existing APIs that do not provide templated  
> interfaces.  What is the easiest way to use these existing functions  
> that minimizes the copying of data from raw C pointers to a  
> container that holds a specific type of boost::units?

On most compilers, the binary layout of quantity<Unit,Y> should be the  
same as that of the value type, Y, so you should be able to do  
something like this :

std::vector<quantity<si::energy,double> >	v(100);

double *vp = reinterpret_cast<double*>(&v.front());

passing the resulting pointer to/from the legacy functions :

do_something_in_legacy_code(vp);

Naturally, you should verify that the layout is really compatible ...

Matthias