G'day All,

Following on from my earlier query on overloading print()....

I've come up with this:


/* < stdcallbk.pyd > */

/*---------------stdcallbk.h---------------------*/
#ifndef STDCALLBK_MODULE_H
#include <Python.h>
#define STDCALLBK_MODULE_H


// Type definition for the callback function.
typedef void __stdcall(CALLBK_FUNC_T)(const char* p);


#ifdef __cplusplus
extern "C" {
#endif
  void register_callback(CALLBK_FUNC_T* callback);
  void import_stdcallbk(void);
#ifdef __cplusplus
}
#endif


#endif    /* #define STDCALLBK_MODULE_H */


/*---------------stdcallbk.c---------------------*/
#include "stdcallbk_module.h"

static CALLBK_FUNC_T *callback_write_func = NULL;
static FILE *fp;    /*for debugging*/
static PyObject* g_stdout;

typedef struct
{
    PyObject_HEAD
    CALLBK_FUNC_T *write;
} Stdout;


static PyObject* write2(PyObject* self, PyObject* args)
{
    const char* p;

    if (!PyArg_ParseTuple(args, "s", &p))
        return NULL;

    fputs(p, fp);    fflush(fp);
    if(callback_write_func)
        callback_write_func(p);
    else
        printf("----%s----", p);

    return PyLong_FromLong(strlen(p));
}

static PyObject* flush2(PyObject* self, PyObject* args)
{
    // no-op
    return Py_BuildValue("");
}


static PyMethodDef Stdout_methods[] =
{
    {"write", write2, METH_VARARGS, "sys-stdout-write"},
    {"flush", flush2, METH_VARARGS, "sys-stdout-write"},
    {NULL, NULL, 0, NULL}
};



static PyTypeObject StdoutType =
{
    PyVarObject_HEAD_INIT(0, 0)
    "stdcallbk.StdoutType", /* tp_name */
    sizeof(Stdout), /* tp_basicsize */
    0, /* tp_itemsize */
    0, /* tp_dealloc */
    0, /* tp_print */
    0, /* tp_getattr */
    0, /* tp_setattr */
    0, /* tp_reserved */
    0, /* tp_repr */
    0, /* tp_as_number */
    0, /* tp_as_sequence */
    0, /* tp_as_mapping */
    0, /* tp_hash */
    0, /* tp_call */
    0, /* tp_str */
    0, /* tp_getattro */
    0, /* tp_setattro */
    0, /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT, /* tp_flags */
    "stdcallbk.Stdout objects", /* tp_doc */
    0, /* tp_traverse */
    0, /* tp_clear */
    0, /* tp_richcompare */
    0, /* tp_weaklistoffset */
    0, /* tp_iter */
    0, /* tp_iternext */
    Stdout_methods, /* tp_methods */
    0, /* tp_members */
    0, /* tp_getset */
    0, /* tp_base */
    0, /* tp_dict */
    0, /* tp_descr_get */
    0, /* tp_descr_set */
    0, /* tp_dictoffset */
    0, /* tp_init */
    0, /* tp_alloc */
    0, /* tp_new */
};


static struct PyModuleDef stdcallbkmodule = {
    PyModuleDef_HEAD_INIT,
    "stdcallbk",   /* name of module */
    NULL, /* module documentation, may be NULL */
    -1,       /* size of per-interpreter state of the module,
                or -1 if the module keeps state in global variables. */
    NULL,
    NULL,
    NULL,
    NULL,
    NULL
};


PyMODINIT_FUNC PyInit_stdcallbk(void)
{
    PyObject* m;

    fp = fopen("debuggered.txt", "wt");
    fputs("got to here Vers 12\n", fp);  fflush(fp);

    StdoutType.tp_new = PyType_GenericNew;
    if (PyType_Ready(&StdoutType) < 0)
        return 0;

    m = PyModule_Create(&stdcallbkmodule);
    if (m)
    {
        Py_INCREF(&StdoutType);
        PyModule_AddObject(m, "Stdout", (PyObject*) &StdoutType);
        fputs("PyModule_AddObject() Called\n", fp); fflush(fp);
    }
    g_stdout = StdoutType.tp_new(&StdoutType, 0, 0);

    /*PySys_SetObject("stdout", g_stdout)*/
fprintf(fp, "PySys_SetObject(stdout) returned %d\n", PySys_SetObject("stdout", g_stdout));
    fflush(fp);

    /*PySys_SetObject("stderr", g_stdout)*/
fprintf(fp, "PySys_SetObject(stderr) returned %d\n", PySys_SetObject("stderr", g_stdout));
    fflush(fp);

    return m;
}




/* called by cpp exe _after_ Py_Initialize(); */
void __declspec(dllexport) import_stdcallbk(void)
{
    PyImport_ImportModule("stdcallbk");
}



/* called by cpp exe _before_ Py_Initialize(); */
void __declspec(dllexport) register_callback(CALLBK_FUNC_T* callback)
{
    PyImport_AppendInittab("stdcallbk", &PyInit_stdcallbk);
    callback_write_func = callback;
}

/* < /stdcallbk.pyd > */




/*------------- Embarcadero C++ Builder exe ---------------------*/
#include "/py_module/stdcallbk_module.h"



void __stdcall callback_write_func(const char* p)
{
    ShowMessage(p);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
    PyObject *pName, *pModule;

    register_callback(callback_write_func);

    Py_Initialize();
    import_stdcallbk();
    //PyRun_SimpleString("import stdcallbk\n");

    pName = PyUnicode_FromString("hello_emb.py");
    pModule = PyImport_Import(pName);
    Py_Finalize();

}
//---------------------------------------------------------------------------



-------------- python script - hello_emb.py ----------------
#import stdcallbk

print("HELLO FRED !")


assert 1==2


------------------------------------------------------------



When run from the cpp exe, I get a messagebox "HELLO FRED!" followed by an empty message box which I assume is the carriage return. All good so far, but when the exception is raised, I get nothing. Nothing is written to the text file either.

But... if I uncomment the "import stdcallbk" from the python script and run it from the command line, I get this:


D:\projects\embed_python3\Win32\Debug>hello_emb.py
----HELLO FRED !--------
--------Traceback (most recent call last):
-------- File "D:\projects\embed_python3\Win32\Debug\hello_emb.py", line 7, in <module>
--------    --------assert 1==2--------
--------AssertionError----------------
----

and this:

D:\projects\embed_python3\Win32\Debug>type debuggered.txt
got to here Vers 12
PyModule_AddObject() Called
PySys_SetObject(stdout) returned 0
PySys_SetObject(stderr) returned 0
HELLO FRED !
Traceback (most recent call last):
File "D:\projects\embed_python3\Win32\Debug\hello_emb.py", line 7, in <module>
    assert 1==2
AssertionError



So it DOES work, just not when it is run from the cpp exe.

Anybody have any idea what on earth is going on here?


Cheers




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