I have been making extensive use of some C++ classes I wrote to do
compile time unit analysis in IMP. I find them very useful and wouldn
t want to have to write code without them and as a result thought I
would ask if others are interested. They enable things like
- automatically converting between different length measures (say
angstroms and nanometers) so you don't have to worry which number is
which
- check that unit types match, so can can't assign an energy value to
a force or daltons to kilograms
- convert between SI units and the energy units used in IMP
etc.
You use them by writing things like
Nanometer side(10);
CubicAngstrom volume= side*side*side;
Nanosecond time_step(10);
simulation_parameters.set_maximum_time_step(time_step); // it
otherwise would want femtoseconds
As a said, I quite like using them and would like to make them
generally available. There are a couple of holdups:
- since it is a compile time library, it doesn't really translate to
python, so we would need to continue to provide separate units and
unit free interfaces for things (for example SimulationParameters has
set_maximum_time_step and set_maximum_time_step_in_femtosecond, the
latter just takes a double
- Boost, has added its own units library (as of 1.36). It is based on
the same principles as mine (they both grew out of a Boost.MPL
example) but there are various differences so converting to the boost
one would take a bit of work and we would need to provide some of our
own code on top of the boost library.
My thought had been to wait until IMP required a new enough boost and
switch to that, but it is taking a while. Are people interested? The
code is pretty stable, but could use a bit of documentation and
cleanup if others are to use it.