8.2 Embedding PyS60

The following code snippet, which prints 'Hello World!' on the screen, demonstrates the embedding of Python interpreter in a C code:

#include <Python.h>
/* This is a GCCE toolchain workaround needed when compiling with GCCE
   and using main() entry point */
#ifdef __GCCE__
#include <staticlibinit_gcce.h>
#endif

int main(void)
{

    SPy_DLC_Init();
    SPy_SetAllocator(SPy_DLC_Alloc, SPy_DLC_Realloc, SPy_DLC_Free, NULL);
    Py_Initialize();
    PyRun_SimpleString("print 'Hello World!'");
    Py_Finalize();
    SPy_DLC_Fini();
    return 0;
}

The basic initialization function is Py_Initialize(). This initializes the table of loaded modules, and creates the fundamental modules __builtin__, __main__ and sys. It also initializes the module search path (sys.path). Py_Finalize() is called when the application is done with its use of Python and wants to free all memory allocated by Python.

PyS60 provides a DLC custom allocator which can be used instead of Python memory allocator. SPy_SetAllocator() is used for redirecting the allocator used by Python. The arguments to this function are the custom functions for allocating, reallocating, freeing the memory and a context pointer in that order. SPy_DLC_Init() is used for initializing the DLC custom allocator. SPy_DLC_Fini() is used for finalizing the DLC custom allocator and doing a memory cleanup. If you want to use your own custom allocator you will have to define the allocation, reallocation and free memory functions and pass the function names to SPy_SetAllocator().

TARGET        helloworld.exe
TARGETTYPE    exe

SYSTEMINCLUDE    \epoc32\include\python25
SYSTEMINCLUDE    \epoc32\include\stdapis
SYSTEMINCLUDE    \epoc32\include

/* Using main() as entry point */
STATICLIBRARY libcrt0.lib

/* libc and euser are always needed when using main() entry point */
LIBRARY libc.lib
LIBRARY euser.lib
LIBRARY python25.lib

SOURCEPATH      ..\src
SOURCE          helloworld.cpp