issue 45: use operator() to fill; issue 44: removed sum(), use std::for_each or std::accumulate instead; added support for stl containers as fill and index arguments

examples/guide_mixed_cpp_python.cpp

@@ -0,0 +1,21 @@
+//[ guide_mixed_cpp_python_part_cpp
+
+#include <boost/python.hpp>
+#include <boost/histogram.hpp>
+
+namespace bh = boost::histogram;
+namespace bp = boost::python;
+
+// function that runs in C++ and accepts reference to dynamic histogram
+void process(bh::dynamic_histogram<>& h) {
+  // fill histogram, in reality this would be arbitrarily complex code
+  for (int i = 0; i < 4; ++i)
+      h(0.25 * i, i);
+}
+
+// a minimal Python module, which exposes the process function to Python
+BOOST_PYTHON_MODULE(cpp_filler) {
+  bp::def("process", process);
+}
+
+//]