Sounds like the thing to do here is signal handling. I'm not an
expert at it myself, but I know it can be done because we use it a
lot in Sage.
- Robert
On Jul 11, 2009, at 8:06 PM, David Simmons-Duffin wrote:
> I'm still working on wrapping the computer algebra package LiE in
> cython. For those unfamiliar, LiE is basically it's own language,
> written in C. And I'm interested in calling some of the math-heavy
> functions, but bypassing the interpreter.
>
> Error checking is sprinkled throughout the LiE source, for instance:
>
> matrix *mat_mul_mat_mat(matrix *a, matrix *b) {
> if (a->ncols != b->nrows)
> error("Number columns arg1 unequal number of rows arg2 .\n");
> return Matmult(a, b);
> }
>
> When an error is found, LiE calls the error() function, which prints
> out a traceback, cleans up a little bit, and finally does a longjump
> to "envbuf," which is at the beginning of the interpreter loop:
>
> void error(char *format, ...)
> {
> symblst list;
> extern jmp_buf envbuf;
> va_list ap;
> va_start(ap, format);
> vfprintf(stderr, format, ap);
> if (am_monitor) vfprintf(monfile, format, ap);
> if (label->name)
> {
> boolean printin = (label->name != seq_name);
> if (printin)
> Printf("(in %s",name_tab[label->name]);
> if (no_terminal(cur_in) || strcmp(label->fname, "stdin")!
> =0) {
> if (!printin) Printf("(");
> Printf(" at line %d of file %s)\n",label->line, label-
>> fname);
> }
> else
> if (printin) Printf(")\n");
> }
> if (fun_name)
> Printf("[in function %s ]\n", name_tab[fun_name]);
> for (list = top_definitions; list!=NULL; list = list->next)
> /* Recover symbol table */
> { if (list->class == FUNCTION_COPIED) list->class = FUNCTION;
> if (list->next && list->next->class == DUMMY)
> list->next = list->next->next; /* Remove sym */
> }
> if (repair_obj) {
> setshared(repair_obj);
> repair_obj = (object) NULL;
> }
> if (cur_in==stdin)
> clear_input();
> else
> do exit_input_file(parsing); while (cur_in!=stdin); /* pop
> input files */
> longjmp(envbuf, -1);
> }
>
> Instead of doing all this stuff, and longjumping to the LiE
> interpreter, I'd like to raise a python exception that could be caught
> by whatever cython function called "mat_mul_mat_mat." Does anyone
> have any advice on how to do this? I took a look at the python
> exception portion of the C/API. It seems like I might want to make a
> C file with my own error function:
>
> error(char* format, ...) {
> turn format into a string
> PyErr_SetString(errorstring)
> longjump somewhere ???
> }
>
> and then comment out the error function in the LiE source... but I'm
> not totally sure how to put it all together. Also, If it's possible,
> I'd like to avoid modifying the LiE source too much -- i.e. commenting
> out an entire function. I'm not a C master, so I wouldn't be
> surprised if I've missed an obvious way to do this.
>
> Thanks for the advice!
>
> David
>
>
>
>
> _______________________________________________
> Cython-dev mailing list
> [email protected]
> http://codespeak.net/mailman/listinfo/cython-dev
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