make generic property interface more pythonic

Instead of doing a.GetFloatProp('foo'), feel free to use
a.foo. a.foo = 3.0 will create a new float property 'foo'.

This commit is brought to you by ZSO Pilatus

modules/base/src/export_helper/generic_property_def.hh

@@ -19,7 +19,8 @@
 
 #ifndef GENERIC_PROPERTY_DEF_HH
 #define GENERIC_PROPERTY_DEF_HH
-
+#include <boost/python.hpp>
+#include <cassert>
 #include <ost/log.hh>
 /*
   Author: Marco Biasini
@@ -130,6 +131,36 @@ String depr_prop_as_string(C& c, const String& k)
   return c.GetPropAsString(k);  
 }
 
+template <typename C>
+boost::python::object get_attr(C& c, const String& k) {
+  std::map<String,ost::GenericPropValue>::const_iterator 
+      i = c.GetPropMap().find(k);
+  boost::python::object obj;
+  if (i != c.GetPropMap().end()) {
+    switch (i->second.which()) {
+      case 0:
+        return boost::python::object(boost::get<String>(i->second));
+      case 1:
+        return boost::python::object(boost::get<Real>(i->second));
+      case 2:
+        return boost::python::object(boost::get<int>(i->second));
+      case 3:
+        return boost::python::object(boost::get<bool>(i->second));
+      default:
+        assert(0 && "unhandled type");
+    }
+  }
+  std::string msg = "no such attribute '" + k + "'";
+  PyErr_SetString(PyExc_AttributeError, msg.c_str());
+  boost::python::throw_error_already_set();
+  // throw_error_already_set is not marked noreturn in some versions of
+  // boost. That's why we need a return statement at the end, even if we
+  // never get here!
+  return obj;
+}
+
+
+
 template <typename C, typename O>
 void const_generic_prop_def(O& bp_class)
 {
@@ -167,6 +198,7 @@ void const_generic_prop_def(O& bp_class)
     .def("GetGenericStringProperty", &depr_get_string_b<C>)
     .def("HasGenericProperty", &depr_has_prop<C>)
     .def("GetGenericPropertyStringRepresentation", &depr_prop_as_string<C>)
+    .def("__getattr__", &get_attr<C>)
   ;
 }
 
@@ -188,6 +220,10 @@ void generic_prop_def(O& bp_class)
     .def("SetGenericBoolProperty", &depr_set_bool<C>)
     .def("SetGenericStringProperty", &depr_set_string<C>)
     .def("RemoveProp", &C::RemoveProp)
+    .def("__setattr__", &C::SetBoolProp)
+    .def("__setattr__", &C::SetIntProp)
+    .def("__setattr__", &C::SetStringProp)
+    .def("__setattr__", &C::SetFloatProp)
   ;
 }