Ralf W. Grosse-Kunstleve 304277b806 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]

2008-05-29 19:48:55 +00:00

8.7 KiB

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