[C++-sig] How to get output from python embedded in VC++

[Jian]

Dear Imre,


Thanks a lot. I'm not using boost::python but the original way from the official website. Main code to invoke py module are below 2 lines.


pName = PyUnicode_DecodeFSDefault("test1");
pModule = PyImport_Import(pName);


and below is my py file:


import emb
print("Number of arguments", emb.numargs())
print("test for 中文(Chinese)")
#import numpy as np
props = []
props = emb.getproperty(23)
print(props)


As you can see above. I have a embedded object (emb) in my C++ program and exposed a function named 'getproperty(int)'. Also there are some output from the py file. what I want is to capture those output and also need to feedback input if needed(if something like input() is used in the future). So I could get data from inside my program and update some part using py file.


In addition, I have tried to redirect std::out by using derived class from std::basic_streambuf. It can be easily redirect to a EDIT control through a callback function(as below code). 


m_newBuffer = new mrsStreamBuf<>(std::cout, outCallBack, &m_cmdWindow);


As a result, only output from std::out are captured. The output from py file are totally missing (Displayed in the separate console window created by my program). Is it because I'm not using boost::python?

Thanks & Best Regards,


John


At 2017-07-21 03:22:47, "Horváth Imre István" <imre.i.horvath at gmail.com> wrote:
>Hi John!
>
>If you want to embed python in c++ app and exchange data between c++ and
>python, take a look at the boost::python library.
>It's also a platform independent solution (my app's target platforms are
>windows vs2015 and linux CentOS7).
>
>You can do something like this:
>
>    using namespace boost::python;
>    Py_Initialize();
>    try {
>        boost::python::object main_module =
>boost::python::import("__main__");
>        boost::python::object main_namespace =
>main_module.attr("__dict__");
>
>        boost::python::dict mydata;
>  	mydata["x"] = 5;
>        mydata["foo"] = boost::python::dict();
>        mydata["foo"]["bar1"] = "data1";
>	mydata["foo"]["bar2"] = "data2";
>
>	// you can declare variables in the python namespace from c++
>        main_namespace["mydata"] = mydata;
>
>        // in the script there is a mydata variable: {'x': 5, 'foo':
>{'bar1': 'data1', 'bar2': 'data2'}}
>        boost::python::object ignored = exec_file("script.py",
>main_namespace, main_namespace);
>        
>        // declare a variable named return_value in the script, 
>        // and you can extract it's value to c++ like this
>	std::wstring output =
>extract<std::wstring>(main_namespace["return_value"]);
>
>    } catch( boost::python::error_already_set) {
>        PyErr_Print();
>    }
>
>(If your python script has some output, don't forget to redirect boost
>std::cout etc)
>
>Best regards:
>Imre
>
>2017. 07. 20, csütörtök keltezéssel 11.25-kor Jian ezt írta:
>> Dear Gurus,
>> 
>> I want to embed python interpreter in my program. What I want is to
>> redirect those output to a control such as RICHEDIT which can be
>> modified as a output window in my program. So I can write *.py files
>> outside of program and invoke it inside program as a script file. In
>> order to get information output by the *.py file I need to get the
>> stdin&stdout. I have tried some workflow but not perfect.
>> 
>> 1). I have tried use Allocconsle(). But I can only get the output info
>> printed by std::out & printf() in the current code. all things which
>> are printed by python35.dll are missing. I used print('xxxx') in the
>> *.py file to test the output. Those *.py files are OK in command line
>> mode.
>> 
>> 2). I also tried to derive class basic_streambuf and overwrite the
>> in/out functions. It works only for output from std::out. Text from
>> printf() as well as from dlls are missing.
>> 
>> 3). then I tried to use linker settings as below. 
>> 
>> #pragma comment( linker,
>> "/subsystem:console /entry:wWinMainCRTStartup" )
>> 
>> A cmd window is created along with the program. everything output from
>> current process and dlls are retrieved successfully as I want. But the
>> cmd window is not easy to control.
>> 
>> Is there a better way for this purpose? 
>> 
>> Thanks in advance for your kind help.
>> 
>> Best Regards,
>> 
>> John. 
>> 
>> 
>> 
>> 
>>  
>> 
>> _______________________________________________
>> Cplusplus-sig mailing list
>> Cplusplus-sig at python.org
>> https://mail.python.org/mailman/listinfo/cplusplus-sig
>
>
>_______________________________________________
>Cplusplus-sig mailing list
>Cplusplus-sig at python.org
>https://mail.python.org/mailman/listinfo/cplusplus-sig
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/cplusplus-sig/attachments/20170721/dc919116/attachment-0001.html>