How do you convert a C++ object to a PyObject?

Question

I have a two c++ objects

    int queueIndex
    Timer timer_obj

and here is the definition of the timer class

class Timer
{

private:
    struct timeval tStart; /**< @brief Stores the system time when the timer is started */
    struct timeval tFinish; /**< @brief Stores the system time when the timer is stopped */

protected:
    float getElapsedTime(struct timeval, struct timeval);

public:
    Timer();
    string currentTime();
    float currentElapsedTime();
    void restart();
    float stop();
    int high_pres_usleep_untill(unsigned long long int);
    string getStringStartTimer();
    void setStartTimerFromString(string);
    void sleep(long int);
    unsigned long long int get_clock();

I need to convert these two objects into PyObj*.I was using boost::python for this purpose.I now wish to do it without boost or swig. I successfully converted Index but im clueless with the timer_obj

    PyObject* pyo=PyInt_FromLong(queueIndex)

I would be thankful if someone could help me with this.I just need an example you dont need to give me the complete code.Also the functions defined in the class are a bit complicated so I did not give them here.Is it possible to convert the timer_obj and then assign a new reference or do i have to obtain new reference for all the structs and functions in the class and create a new class with these references?

What exactly are you trying to accomplish by 'converting the C++ objects'? boost::python is meant for interoperability, so I assume you want to make a C++ application "extensible" with Python code, right? Maybe cython.org could help you? — Andrei Sosnin
– Andrei Sosnin, Commented Dec 11, 2012 at 7:29
Well i am working on client to service platform written in c++ and the logic the service has to implement in written in python.Until now i have been using boost but recently i have been asked to change the interpreter method where i can't use boost anymore — Tyranicangel
– Tyranicangel, Commented Dec 12, 2012 at 9:42

Nathan Binkert · Accepted Answer · 2012-12-13 22:34:21Z

2

What you need to do is create an extension type. Unfortunately, the process is relatively involved, and will take a couple hundred lines of code. That's the whole python of boost::python and SWIG, to remove all the boilerplate.

answered Dec 13, 2012 at 22:34

Nathan Binkert

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2 Comments

Tyranicangel Over a year ago

Currently in the Py script i need only the function getElapsedtime().Is there any possibility to retrieve it without completely converting the timer Object

Nathan Binkert Over a year ago

If you only need the one function, you can create a CObject docs.python.org/2/c-api/cobject.html. That will basically let you pass an opaque void pointer to python. You can then expose getElapsedTime() as a function that takes your CObject as a parameter. (You'll also need to create a function that generates those CObjects somehow so you can pass them to python).

Community · Accepted Answer · 2017-05-23 12:16:01Z

1

As Nathan said, extension type is relatively involved. You would like to explore Cython for this as syntax is easier and it takes care of generating boilerplate internally. http://docs.cython.org/src/userguide/wrapping_CPlusPlus.html

You also can take a look at example posted by Niklas in https://stackoverflow.com/a/8933819/2156678

edited May 23, 2017 at 12:16

CommunityBot

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answered Mar 20, 2013 at 12:38

Amit

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