🌐 Mailman 3 March 2000 - Python-list - python.org

Further help with Object Caching
by Brent Fulgham March 1, 2000

March 1, 2000

I must be missing something obvious. I seem to be able to throw objects into strings without a problem, but they don't come out of the Cache alive :-) I whittled it further, to the point where it doesn't seem that the Cache is the issue, but rather the way I am storing objects. The following pseudo-code snippet shows the problem (taken from my program with the logging methods removed for clarity) (Note that the variable 'code' is a valid PyCodeObject*) ============================================================ // Create a cacheable code object by writing it to a string, // then converting the string to a char* PyObject* codeString; PyObject* test; PyObject* test2; char* cacheable; char* store2; int length; codeString = PyMarshal_WriteObjectToString((PyObject*)code); cacheable = PyString_AsString(codeString); length = PyObject_Length(codeString); // Test 1 -- Works test = PyMarshal_ReadObjectFromString((char*)cacheable, length); if (test == NULL) { // Log error message } // Test 2 -- Fails store2 = (char*)malloc(length * sizeof(char)) strncpy(store2, cacheable, length); // Use copy to build object test2 = PyMarshal_ReadObjectFromString((char*)store2, length); if (test2 == NULL) { // Throw tantrum } ===================================================== The 'test2' case fails. The first thing that comes to mind is that the "length" I am getting from PyObject_Length is wrong. Perhaps there is header or trailer data that is being included that should not, or information that is missing. Can anyone help shed some light on this? Thanks, -Brent

1 0

Microsoft Access Database
by Eric Kappotis March 1, 2000

March 1, 2000

Is there anyway i can read from and write to a Microsoft Access Database with Python. If so where can i find some tutorials on how to do that? Eric Kappotis

3 2

Re: ANNOUNCE: Python Compiler (No spell errors)
by François Pinard March 1, 2000

March 1, 2000

Andreas Otto <aotto(a)t-online.de> writes: > After implementation of Tcl as compiler-language we have plans for > python. By `python' we usual refer to the system command. We write Python, with a capital, for the programming language. I get that you did not really study, nor use this language yet. You are having _plans_ for Python, indeed? I surely got that you want to make money out of it (there is nothing wrong with that), but I'm still curious about the technical contents of your plans, if about something you do not know yet. I guess you might have to establish some kind of credibility for yourself about Python, before starting to speak business. -- François Pinard http://www.iro.umontreal.ca/~pinard

7 6

possible problem with the mysqldb interface
by crypt＠ihug.co.nz March 1, 2000

March 1, 2000

hi I am converting code written for the old mysql interface that makes extensive use of the fetchdict() method. I would like to continue using this as it makes reduces code errors for many case. The problem that I have is that there does not seem to be enough information provided by the api to implement this is a reliable manner. Any suggestions n how to do this. I had intended to use the information provided in cursor.description but for some reason this does not provide the name of the table therefore can not be used. Joe. -- ======================================================================= in real life: Joseph Skinner |There's no such thing as a wizard email: crypt(a)ihug.co.nz |who minds his own business Analyst/Programmer | - Berengis the Black | Court Mage to the Earls Caeline ========================================================================

1 0

thanks for the help !!!!...any tips for how to best learn python?!!!
by Collin Greene March 1, 2000

March 1, 2000

any tips to help me newbie # 1 get started at prgramming in python, thanks any help is appreaceated!!:) greene(a)hctc.com

2 1

Reimplementing Lib/codeop.py in C fails...
by Alex Farber March 1, 2000

March 1, 2000

Dear colleagues, I am trying to create a custom "readline" function in C. I have looked at Modules/readline.c, Python/pythonrun.c and Parser/myreadline.c. I've also read the http://www.python.org/doc/current/api/api.html and many postings in Deja.com... I would very appreciate any hints. Here is a simple C code reimplementing Lib/codeop.py for test purposes: int main(int argc, char* argv[]) { char* line; PyObject *globals, *source; Py_Initialize(); globals = PyDict_New(); PyDict_SetItemString(globals, "__builtins__", PyEval_GetBuiltins()); /* while (1) { line = readline(">>> "); */ printf("\nCompiling <for i in [1,2,3]:>\n"); source = Py_CompileString("for i in [1,2,3]:", "<stdin>", Py_file_input); if (source == NULL) PyErr_Print(); printf("\nCompiling <for i in [1,2,3]:\\n>\n"); source = Py_CompileString("for i in [1,2,3]:\n", "<stdin>", Py_file_input); if (source == NULL) PyErr_Print(); printf("\nCompiling <for i in [1,2,3]:\\n\\n>\n"); source = Py_CompileString("for i in [1,2,3]:\n\n", "<stdin>", Py_file_input); if (source == NULL) PyErr_Print(); /* free(line); } */ Py_DECREF(globals); Py_Finalize(); exit(0); } Which produces the following output: Compiling <for i in [1,2,3]:> File "<string>", line 1 for i in [1,2,3]: ^ SyntaxError: unexpected EOF while parsing Compiling <for i in [1,2,3]:\n> File "<string>", line 1 for i in [1,2,3]: ^ SyntaxError: unexpected EOF while parsing Compiling <for i in [1,2,3]:\n\n> File "<string>", line 2 ^ SyntaxError: invalid syntax However the comment in Lib/codeop.py suggests, that the errors in the first and the second case should be different. How can I see this difference in my C code? Shouldn't the second string compile? Regards Alex PS: The background is that I am programming a 3D-viewer in C++ which uses some finite elements library (written in my university; not thread-safe), Qt (not thread-safe) and which embeds Python. Because of the not-thread-safeness I have to run FE, Qt and Python in the same thread. But then I can not run PyRun_InteractiveLoop() or PyRun_InteractiveOne() - the Qt would "freeze". So I am running a readline in another thread and send received strings to a UNIX-pipe. Those strings should be read by the first thread and executed with PyRun_SimpleString(). Now I get the problem with the strings like "for i in [1,2,3]:" - the Python needs more input. To detect such cases I was hoping to mimic the Lib/codeop.py and then either save the received string (if more input is needed) or run it with PyEval_EvalCode().

1 0