[C++-sig] (Stefan Seefeld) pass function pointerto c

[Qinfeng(Javen) Shi]

Hi Stefan,

Thanks very much.

> make that
>float f = boost::python::extract<float>(rlt);
>Would that work ?
It works if arg_op = plus or minus. ( here process(boost::python::object
arg_op)).
But it didn't work if arg_op = vectorPlus. It seems that arg_op can't accept
a c++ float pointer.

Acctually the real vectorPlus() used in my code has been optimized for speed
and kindof unfriendly readable. I listed the simple version of vectorPlus()
which had the same idea and problem. For speed reason, I can't use
plus(p1[i],p2[i]) instead of vectorPlus(p1,p2,length).So I hope vectorPlus
can work.

---------------------c extension-----------------
vectorPlus(float* p1, float* p2,int point_len)// plus for two vectors.
{
   float sum = 0;
   for (int i=0;i<point_len;i++)
   {
        sum += *(p1+i) + *(p2+i);
   }
   return (sum);
}

boost::python::object op;

void process(boost::python::object arg_op){
  ...
  op = arg_op;
  ...
  float * a = {1,2};
  float * b = {3,4};

  boost::python::object rlt = op(a,b,2); // can't accept float* parameters.
  float * f = boost::python::extract<float> (rlt);
  printf("%f \n",*f);
  ...
}
----------------------result --------------------
>>> import hello
>>> hello.process(hello.vectorPlus)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: No to_python (by-value) converter found for C++ type: float*
>>>


-- 
Qinfeng(Javen) Shi

Research School of Information Sciences and Engineering
Australian National University
Locked Bag 8001
Canberra ACT 2601
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