James,
I believe this example snippet performs the function you want.
*diff --git a/rstbx/diffraction/fastbragg/fastbragg_ext.cpp
b/rstbx/diffraction/fastbragg/fastbragg_ext.cpp*
*index d544d22..380e84f 100644*
*--- a/rstbx/diffraction/fastbragg/fastbragg_ext.cpp*
*+++ b/rstbx/diffraction/fastbragg/fastbragg_ext.cpp*
@@ -22,6 +22,13 @@ namespace boost_python { namespace {
{
return boost::python::make_tuple(1,2,3,4);
}
+
+ static double
+ get_distance_mm(camera const& c) { return c.distance*1000.; }
+
+ static void
+ set_distance_mm(camera& c, double const& value) {
+ c.distance = value/1000.;}
void
init_module() {
@@ -57,6 +64,9 @@ namespace boost_python { namespace {
.add_property("distance",
make_getter(&camera::distance,rbv()),
make_setter(&camera::distance,dcp()))
+ .add_property("distance_mm",
+ make_function(&get_distance_mm,rbv()),
+ make_function(&set_distance_mm,dcp()))
.add_property("Ybeam",
make_getter(&camera::Ybeam,rbv()),
make_setter(&camera::Ybeam,dcp()))
Use it with this example python script:
from rstbx.diffraction.fastbragg import camera
c = camera()
c.distance = 10. # meters
print "distance is %f millimeters"%( c.distance_mm )
c.distance_mm = 10.
print "distance is %f meters"%( c.distance )
Output is:
distance is 10000.000000 millimeters
distance is 0.010000 meters
So problem solved.
Nick
Nicholas K. Sauter, Ph. D.
Senior Scientist, Molecular Biophysics & Integrated Bioimaging Division
Lawrence Berkeley National Laboratory
1 Cyclotron Rd., Bldg. 33R0345
Berkeley, CA 94720
(510) 486-5713
On Tue, Feb 21, 2017 at 5:08 PM, Nicholas Sauter
http://phenix-online.org/mailman/listinfo/cctbxbbQuick question from James Holton and myself.
We want to use a boost python *.add_property() to add a make_getter and make_setter to our wrapper, so we can expose a class variable to the Python layer.
However, we want to execute a change of measurement units, i.e., the Python value will always be given in millimetres, and the C++ value always in metres.
How can this be done within a simple add_property() paradigm?
Nick