See Python C++-SIG thread: "object.attr(object& attrname) proposal"

Started 2008-05-25 by hohehohe2@gmail.com.

Excerpts:

If char const* is passed to objecjt.attr(), it uses
PyObject_GetAttrStrng() or PyObject_SetAttrStrng().  If object is
passed to objecjt.attr(), it takes the object as a Python string
object and uses PyObject_GetAttr() or PyObject_SetAttr().

If attr() behaves like this, it can be useful when there are lots
of objects which you know have the same attribute name. You can save
time by first making a boost::python::object and passing it to every
object's attr() inside a loop.

I just made a bit of modification to boost:python locally and did a
quick test, like

test 1:
  for(int i = 0; i < n; ++i)
  {
    omain.attr(attrname) = 444; //attrname is a char const*
  }

test 2:
  for(int i = 0; i < n; ++i)
  {
    object o = omain.attr(attrname); //attrname is a char const*
  }

test 3:
  for(int i = 0; i < n; ++i)
  {
    omain.attr(oaaaa) = 444; //oaaaa is boost::python::object that represents a string
  }

test 4:
  for(int i = 0; i < n; ++i)
  {
    object o = omain.attr(oaaaa); //oaaaa is boost::python::object that represents a string
  }

and it reasonably reflected the difference between PyObject_*Attr() and PyObject_*AttrString.

test 1 :2783ms
test 2 :2357ms
test 3 :1882ms
test 4 :1267ms

test5: PyObject_SetAttrString(po_main, "aaaa", po_num444);
test6: Py_DECREF(PyObject_GetAttrString(po_main, "aaaa"));
test7: PyObject_SetAttr(po_main, po_aaaa, po_num444);
test8: Py_DECREF(PyObject_GetAttr(po_main, po_aaaa));
(po_ prefixed variables are PyObject*),

all inside each for loop, and the results were

test 5 :2410ms
test 6 :2277ms
test 7 :1629ms
test 8 :1094ms

It's boost 1.35.0, Python 2.5 on linux(gcc4.1.2).
I also did the same test on windows(vs8) and the tendency was not
so different.


[SVN r45918]

test/object.cpp

@@ -38,26 +38,61 @@ object obj_getattr(object x, char const* name)
     return x.attr(name);
 }
 
+object obj_objgetattr(object x, object const& name)
+{
+    return x.attr(name);
+}
+
 object obj_const_getattr(object const& x, char const* name)
 {
     return x.attr(name);
 }
 
+object obj_const_objgetattr(object const& x, object const& name)
+{
+    return x.attr(name);
+}
+
 void obj_setattr(object x, char const* name, object value)
 {
     x.attr(name) = value;
 }
 
+void obj_objsetattr(object x, object const& name, object value)
+{
+    x.attr(name) = value;
+}
+
 void obj_setattr42(object x, char const* name)
 {
     x.attr(name) = 42;
 }
 
+void obj_objsetattr42(object x, object const& name)
+{
+    x.attr(name) = 42;
+}
+
 void obj_moveattr(object& x, char const* src, char const* dst)
 {
     x.attr(dst) = x.attr(src);
 }
 
+void obj_objmoveattr(object& x, object const& src, object const& dst)
+{
+    x.attr(dst) = x.attr(src);
+}
+
+void obj_delattr(object x, char const* name)
+{
+    x.attr(name).del();
+}
+
+void obj_objdelattr(object x, object const& name)
+{
+    x.attr(name).del();
+}
+
 object obj_getitem(object x, object key)
 {
     return x[key];
@@ -108,11 +143,21 @@ bool test_attr(object y, char* name)
     return y.attr(name);
 }
 
+bool test_objattr(object y, object& name)
+{
+    return y.attr(name);
+}
+
 bool test_not_attr(object y, char* name)
 {
     return !y.attr(name);
 }
 
+bool test_not_objattr(object y, object& name)
+{
+    return !y.attr(name);
+}
+
 bool test_item(object y, object key)
 {
     return y[key];
@@ -301,11 +346,17 @@ BOOST_PYTHON_MODULE(object_ext)
     def("number", number);
 
     def("obj_getattr", obj_getattr);
+    def("obj_objgetattr", obj_objgetattr);
     def("obj_const_getattr", obj_const_getattr);
+    def("obj_const_objgetattr", obj_const_objgetattr);
     def("obj_setattr", obj_setattr);
+    def("obj_objsetattr", obj_objsetattr);
     def("obj_setattr42", obj_setattr42);
+    def("obj_objsetattr42", obj_objsetattr42);
     def("obj_moveattr", obj_moveattr);
-
+    def("obj_objmoveattr", obj_objmoveattr);
+    def("obj_delattr", obj_delattr);
+    def("obj_objdelattr", obj_objdelattr);
 
     def("obj_getitem", obj_getitem);
     def("obj_getitem3", obj_getitem);
@@ -319,7 +370,9 @@ BOOST_PYTHON_MODULE(object_ext)
     def("test_not", test_not);
 
     def("test_attr", test_attr);
+    def("test_objattr", test_objattr);
     def("test_not_attr", test_not_attr);
+    def("test_not_objattr", test_not_objattr);
 
     def("test_item", test_item);
     def("test_not_item", test_not_item);