How to embed Python in a C++ Builder 2010 (not Delphi) application?

Question

I'm trying to embed Python in a C++Builder application for Windows.

After many research on the subject ( example ), I have found the Python4Delphi project that seems very interesting and exactly what I'm trying to do. The thing is that I'm not using Delphi (and I don't really want to use it) but only C++Builder.

I have also found some examples to embed Python in C++ projects ( example ), so I am trying this method. The problem is I can not compile even the first simple "Hello world" example.

Here are the steps I followed:

1. Creating in C++ builder a New console application project
2. Include Python.h files
3. compile the following code:

#pragma hdrstop
#pragma argsused

#ifdef _WIN32
#include <tchar.h>
#else
  typedef char _TCHAR;
  #define _tmain main
#endif

#include <stdio.h>
#include <conio.h>
#include <Python.h>

int main()
{
    PyObject* pInt;

    Py_Initialize();

    PyRun_SimpleString("print('Hello World from Embedded Python!!!')");

    Py_Finalize();

    printf("\nPress any key to exit...\n");
    if(!_getch()) _getch();
    return 0;
}

During the compilation I am getting the following error multiples times:

[bcc32c Error] pymath.h(22): declaration conflicts with target of using declaration already in scope.

This happens, for example, when line 22 from pymath.h is compiled:

#ifndef HAVE_ROUND
extern double round(double);
#endif

I think it probably comes because of compiler and/or pyconfig.h configuration. As a beginner in C++ and this king of thing, it is difficult for me to solve this problem.

Can you help me, do you have any suggestion?

EDIT

Since April 2020, C++Builder seems to support the Boost library, which can be used to implement Python in a C++ program. So the previous errors no longer appear, instead I have a different error.

Using the same script as before, but using #include <boost/Python.hpp> , I have the error:

[ilink32 Error] Fatal: Impossible to open the file 'LIBBOOST_PYTHON38-BCB32C-MT-S-X32-1_68.LIB'

Do you have an idea to solve this problem?

Answer 1

I used C++Builder 10.4 with Python4Delphi.

I have Python for Windows installed:

Python version 3.8.2 (tags/v3.8.2:7b3ab59, Feb 25 2020, 22:45:29) [MSC v.1916 32 bit (Intel)] Version info. sys.version_info(major=3, minor=8, micro=2, releaselevel='final', serial=0)

Steps to install and test:

1. Grabbed the latest release of Python4Delphi on GitHub ( https://github.com/pyscripter/python4delphi ). Unzipped it to my projects folder.

2. Opened the Python_D.dproj package project.

3. Set the Project Options for the Delphi Compiler | C/C++ Output file generation option to Generate all C++Builder files (including package libs)

4. Built and installed the Delphi4Python components

5. Opened the Demo1 Delphi project and tested it to make sure that I had the components and Python working. C:\\Users\\david\\Documents\\Embarcadero\\Studio\\Projects\\Python4Delphi\\python4delphi-master\\Demos\\Demo01

6. Created a New C++Builder VCL application. Copied all of the components from the Delphi Demo01 form.

7. added event handlers for the 3 buttons:

   void __fastcall TForm2::Button1Click(TObject *Sender) { PythonEngine1->ExecStrings( Memo1->Lines ); } //---------------------------------------------------------------------------

   void __fastcall TForm2::Button2Click(TObject *Sender) { if (OpenDialog1->Execute()) { Memo1->Lines->LoadFromFile( OpenDialog1->FileName ); } } //---------------------------------------------------------------------------

   void __fastcall TForm2::Button3Click(TObject *Sender) { if (SaveDialog1->Execute()) { Memo1->Lines->SaveToFile( SaveDialog1->FileName ); } }

8. Did a project make - when asked where the header file and lib files were I pointed them to (you could also just update the project's search directories).

PythonEngine.hpp - C:\\Users\\david\\Documents\\Embarcadero\\Studio\\Projects\\Python4Delphi\\python4delphi-master\\Source

Python_D.bpi, Python_D.dcp, Python_D.lib - C:\\Users\\Public\\Documents\\Embarcadero\\Studio\\21.0\\Dcp

9. Ran the Demo1 C++ version - and could put in Python script code and test successfully :D

I'll work on a blog post where I can put screen shots and source code link.

Don't have C++BUilder 2020 installed anywhere for now. I think you should be able to use the Delphi command line compiler that comes with C++Builder but will have to try this - I have RAD Studio 10.4 and RAD Studio 10.4.1 on separate machines.

Answer 2

According to Python documentation, Borland compiler is supported.

So, at the moment, the only way is to revert back to the use "Classic Borland Compiler" in the "Project Options > Building > C++ Compiler" tab.

Then you need to create OMF compatible libs out of the dlls provided with the installation and add them to the project:

implib -aa python3.lib python3.dll
implib -aa python39.lib python39.dll

If you get a linker error:

[ilink32 Error] Error: Unresolved external '__Py_RefTotal' referenced from ...
[ilink32 Error] Error: Unresolved external '__Py_NegativeRefcount' referenced from ...

you need to modify the include file pyconfig.h:

#ifdef _DEBUG
//#       define Py_DEBUG  <<--- comment this!!
#endif