performance question when using embedding/extending

[Eibl Christian Object Vision]

hi,

i need to call a python function from my c++ app and this python function in
turn
accesses an instanciated c++ object (i pass the pointer to the object as a
parameter).
in the python function i have approx. 20-30 calls to the object (simple
member accessing).

the goal:
provide a scripting interface for computation of certain parameters
depending on the
state of a changing object...

when i'm doing a simple performance test (just calling the function 100.000
times in c++)
it turns out that on my 300MHZ PII the function is called 32.000 times per
second if
i don't access any attributes via python and it goes down to 900 times per
second if
i place 30 access calls in the python function.

i "quantified" the application an see that almost all the cpu-time is used
in "PyEval_CallObject".
the application i'm building needs at least 10-times the performance it has
now...

my question:
 - is this just the (slow) way it is ?
 - is there a faster way to use embedding/extending (details see below) ?
 - is python not suitable for this task (the old system was also an
interpreter, but specifically
    written for this task) ?


the details::

i'm using the following code in my app to call a python function in a
module:

<snip>
 _pythonCaller_p->runWithObject( "i", &finalResult, somePtr_p,
"_SomeClass_p" )
</snip>

the "runWithObject" method is defined as follows:
NOTE: i'm using SWIG with shadow classes to generate python interfaces for
my C++ classes!

<snip>
bool PythonCaller::runWithObject( char* resultFormat, void* result_p, void*
pyObj_p, char* pyType)
{      
      PyObject* func_p = 0;
      PyObject* args_p = 0;
      PyObject* resu_p = 0;
      if( _doReload ) {
         func_p = loadAttribute( _moduleName, _functionName );
      }
      else {
         func_p = _pyFunction;
      }
      if( func_p==0 ) {
         return false;
      }
      char aTmp[256];
      SWIG_MakePtr( aTmp, pyObj_p, pyType );
      args_p = Py_BuildValue( "(s)", aTmp );
      if( args_p==0 ) {
         return false;
      }
      resu_p = PyEval_CallObject( func_p, args_p );
      if( resu_p==0 ) PyErr_Print();
      if( _doReload ) {
         Py_DECREF(func_p);
      }
      Py_DECREF(args_p);
</snip>

the python function called with this code is defined as follows:

import Mc
import Mcc

def calcAttrFinalCoding(mp) :
   mpi = Mc.MailpiecePtr( mp )
   mpc = mpi.fetch()

   if mpc.getPbrInfoStatus() == Mcc.barcodeOk :
      return Mcc.attrCodBc
   if mpi.getBvInfoStatus() == Mcc.barcodeOk :
      return Mcc.attrCodBc
   if mpi.getPbrInfoStatus()  == Mcc.barcodeOk :
      return Mcc.attrCodBc
   if mpi.getBvInfoStatus() == Mcc.barcodeOk :
      return Mcc.attrCodBc
   if mpi.getPbrInfoStatus()  == Mcc.barcodeOk :
      return Mcc.attrCodBc
   return 1

thanx for any help!
Chris

--
Christian Eibl
 Object Vision Software AG, München
 Christian.Eibl at ovsag.de | www.ovsag.de
 mobile: +49.171.7623844 or +43.676.3060031

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