On 01/09/2010 01:52 PM, devin kelly wrote:
Hello,
I'm trying to expose some data that I develop in C++ to python.
Basically, the reverse of this sample code:
#include <iostream>
#include <python2.6/Python.h>
#include <boost/python.hpp>
#include <boost/python/exec.hpp>
int main(){
Py_Initialize();
object main_module = import("__main__");
object main_namespace = main_module.attr("__dict__");
ignored = exec("result = 5 ** 2", main_namespace);
int five_squared = extract<int>(main_namespace["result"]);
std::cout << five_squared << std::endl;
return 0;
}
So this code starts the python interpreter, squares 5 (in python) and
then extracts the result to an int called five_squared. This works
fine for me, it's basically an example straight out of the
boost.python webpage.
What I'd really like to do though is have an int that I initialize in
C++ and then square in python. So this would require me to pass (or
expose) that data to python. I've been trying this for a while and
have had no luck whatsoever. The best I can think of is code like this:
int main(){
Py_Initialize();
object main_module = import("__main__");
object main_namespace = main_module.attr("__dict__");
main_namespace["num2square"] = 6;
ignored = exec("result = num2square ** 2", main_namespace);
int five_squared = extract<int>(main_namespace["result"]);
std::cout << five_squared << std::endl;
return 0;
}
This doesn't work. Python throws an error. What am I doing wrong??
It might help indicating what error Python actually throws.
Also, if all you want is to evaluate an expression, I'd suggest you use
"eval()", not "exec()".
Stefan
--
...ich hab' noch einen Koffer in Berlin...
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