misc py/rna changes
[blender.git] / source / blender / python / intern / bpy_interface.c
1
2 #include <stdio.h>
3 #include <stdlib.h>
4 #include <string.h>
5 #include <sys/stat.h>
6
7 #ifndef WIN32
8 #include <dirent.h>
9 #else
10 #include "BLI_winstuff.h"
11 #endif
12
13 #include <Python.h>
14 #include "compile.h"            /* for the PyCodeObject */
15 #include "eval.h"               /* for PyEval_EvalCode */
16
17 #include "bpy_compat.h"
18
19 #include "bpy_rna.h"
20 #include "bpy_operator.h"
21 #include "bpy_ui.h"
22 #include "bpy_util.h"
23
24 #include "DNA_anim_types.h"
25 #include "DNA_space_types.h"
26 #include "DNA_text_types.h"
27
28 #include "MEM_guardedalloc.h"
29
30 #include "BLI_util.h"
31 #include "BLI_fileops.h"
32 #include "BLI_string.h"
33
34 #include "BKE_context.h"
35 #include "BKE_fcurve.h"
36 #include "BKE_text.h"
37
38 #include "BPY_extern.h"
39
40 #include "../generic/bpy_internal_import.h" // our own imports
41 /* external util modules */
42
43 #include "../generic/Mathutils.h"
44 #include "../generic/Geometry.h"
45 #include "../generic/BGL.h"
46
47
48 void BPY_free_compiled_text( struct Text *text )
49 {
50         if( text->compiled ) {
51                 Py_DECREF( ( PyObject * ) text->compiled );
52                 text->compiled = NULL;
53         }
54 }
55
56 /*****************************************************************************
57 * Description: Creates the bpy module and adds it to sys.modules for importing
58 *****************************************************************************/
59 static void bpy_init_modules( void )
60 {
61         PyObject *mod;
62         
63         mod = PyModule_New("bpy");
64         
65         PyModule_AddObject( mod, "data", BPY_rna_module() );
66         /* PyModule_AddObject( mod, "doc", BPY_rna_doc() ); */
67         PyModule_AddObject( mod, "types", BPY_rna_types() );
68         PyModule_AddObject( mod, "props", BPY_rna_props() );
69         PyModule_AddObject( mod, "__ops__", BPY_operator_module() ); /* ops is now a python module that does the conversion from SOME_OT_foo -> some.foo */
70         PyModule_AddObject( mod, "ui", BPY_ui_module() ); // XXX very experimental, consider this a test, especially PyCObject is not meant to be permanent
71         
72         /* add the module so we can import it */
73         PyDict_SetItemString(PySys_GetObject("modules"), "bpy", mod);
74         Py_DECREF(mod);
75
76
77         /* stand alone utility modules not related to blender directly */
78         Geometry_Init("Geometry");
79         Mathutils_Init("Mathutils");
80         BGL_Init("BGL");
81 }
82
83 #if (PY_VERSION_HEX < 0x02050000)
84 PyObject *PyImport_ImportModuleLevel(char *name, void *a, void *b, void *c, int d)
85 {
86         return PyImport_ImportModule(name);
87 }
88 #endif
89
90 void BPY_update_modules( void )
91 {
92         PyObject *mod= PyImport_ImportModuleLevel("bpy", NULL, NULL, NULL, 0);
93         PyModule_AddObject( mod, "data", BPY_rna_module() );
94         PyModule_AddObject( mod, "types", BPY_rna_types() );
95 }
96
97 /*****************************************************************************
98 * Description: This function creates a new Python dictionary object.
99 *****************************************************************************/
100 static PyObject *CreateGlobalDictionary( bContext *C )
101 {
102         PyObject *mod;
103         PyObject *dict = PyDict_New(  );
104         PyObject *item = PyUnicode_FromString( "__main__" );
105         PyDict_SetItemString( dict, "__builtins__", PyEval_GetBuiltins(  ) );
106         PyDict_SetItemString( dict, "__name__", item );
107         Py_DECREF(item);
108         
109         // XXX - evil, need to access context
110         BPy_SetContext(C);
111         
112         // XXX - put somewhere more logical
113         {
114                 PyMethodDef *ml;
115                 static PyMethodDef bpy_prop_meths[] = {
116                         {"FloatProperty", (PyCFunction)BPy_FloatProperty, METH_VARARGS|METH_KEYWORDS, ""},
117                         {"IntProperty", (PyCFunction)BPy_IntProperty, METH_VARARGS|METH_KEYWORDS, ""},
118                         {"BoolProperty", (PyCFunction)BPy_BoolProperty, METH_VARARGS|METH_KEYWORDS, ""},
119                         {"StringProperty", (PyCFunction)BPy_StringProperty, METH_VARARGS|METH_KEYWORDS, ""},
120                         {NULL, NULL, 0, NULL}
121                 };
122                 
123                 for(ml = bpy_prop_meths; ml->ml_name; ml++) {
124                         PyDict_SetItemString( dict, ml->ml_name, PyCFunction_New(ml, NULL));
125                 }
126         }
127         
128         /* add bpy to global namespace */
129         mod= PyImport_ImportModuleLevel("bpy", NULL, NULL, NULL, 0);
130         PyDict_SetItemString( dict, "bpy", mod );
131         Py_DECREF(mod);
132         
133         return dict;
134 }
135
136 /* Use this so we can include our own python bundle */
137 #if 0
138 wchar_t* Py_GetPath(void)
139 {
140         int i;
141         static wchar_t py_path[FILE_MAXDIR] = L"";
142         char *dirname= BLI_gethome_folder("python");
143         if(dirname) {
144                 i= mbstowcs(py_path, dirname, FILE_MAXDIR);
145                 printf("py path %s, %d\n", dirname, i);
146         }
147         return py_path;
148 }
149 #endif
150
151
152 /* must be called before Py_Initialize */
153 void BPY_start_python_path(void)
154 {
155         char *py_path_bundle= BLI_gethome_folder("python");
156
157         if(py_path_bundle==NULL)
158                 return;
159
160         /* set the environment path */
161         printf("found bundled python: %s\n", py_path_bundle);
162
163         BLI_setenv("PYTHONHOME", py_path_bundle);
164         BLI_setenv("PYTHONPATH", py_path_bundle);
165 }
166
167
168 void BPY_start_python( int argc, char **argv )
169 {
170         PyThreadState *py_tstate = NULL;
171         
172         BPY_start_python_path(); /* allow to use our own included python */
173
174         Py_Initialize(  );
175         
176 #if (PY_VERSION_HEX < 0x03000000)
177         PySys_SetArgv( argc, argv);
178 #else
179         /* sigh, why do python guys not have a char** version anymore? :( */
180         {
181                 int i;
182                 PyObject *py_argv= PyList_New(argc);
183
184                 for (i=0; i<argc; i++)
185                         PyList_SET_ITEM(py_argv, i, PyUnicode_FromString(argv[i]));
186
187                 PySys_SetObject("argv", py_argv);
188                 Py_DECREF(py_argv);
189         }
190 #endif
191         
192         /* Initialize thread support (also acquires lock) */
193         PyEval_InitThreads();
194         
195         
196         /* bpy.* and lets us import it */
197         bpy_init_modules(); 
198
199         { /* our own import and reload functions */
200                 PyObject *item;
201                 //PyObject *m = PyImport_AddModule("__builtin__");
202                 //PyObject *d = PyModule_GetDict(m);
203                 PyObject *d = PyEval_GetBuiltins(  );
204                 PyDict_SetItemString(d, "reload",               item=PyCFunction_New(bpy_reload_meth, NULL));   Py_DECREF(item);
205                 PyDict_SetItemString(d, "__import__",   item=PyCFunction_New(bpy_import_meth, NULL));   Py_DECREF(item);
206         }
207         
208         py_tstate = PyGILState_GetThisThreadState();
209         PyEval_ReleaseThread(py_tstate);
210 }
211
212 void BPY_end_python( void )
213 {
214         PyGILState_Ensure(); /* finalizing, no need to grab the state */
215         
216         // free other python data.
217         //BPY_rna_free_types();
218         
219         Py_Finalize(  );
220         
221         return;
222 }
223
224 /* Can run a file or text block */
225 int BPY_run_python_script( bContext *C, const char *fn, struct Text *text, struct ReportList *reports)
226 {
227         PyObject *py_dict, *py_result;
228         PyGILState_STATE gilstate;
229         
230         if (fn==NULL && text==NULL) {
231                 return 0;
232         }
233         
234         //BPY_start_python();
235         
236         gilstate = PyGILState_Ensure();
237
238         BPY_update_modules(); /* can give really bad results if this isnt here */
239         bpy_import_main_set(CTX_data_main(C));
240         
241         py_dict = CreateGlobalDictionary(C);
242
243         if (text) {
244                 
245                 if( !text->compiled ) { /* if it wasn't already compiled, do it now */
246                         char *buf = txt_to_buf( text );
247
248                         text->compiled =
249                                 Py_CompileString( buf, text->id.name+2, Py_file_input );
250
251                         MEM_freeN( buf );
252
253                         if( PyErr_Occurred(  ) ) {
254                                 BPy_errors_to_report(reports);
255                                 BPY_free_compiled_text( text );
256                                 PyGILState_Release(gilstate);
257                                 return 0;
258                         }
259                 }
260                 py_result =  PyEval_EvalCode( text->compiled, py_dict, py_dict );
261                 
262         } else {
263                 FILE *fp= fopen(fn, "r");               
264                 if(fp) {
265                         py_result = PyRun_File(fp, fn, Py_file_input, py_dict, py_dict);
266                         fclose(fp);
267                 }
268                 else {
269                         PyErr_Format(PyExc_SystemError, "Python file \"%s\" could not be opened: %s", fn, strerror(errno));
270                         py_result= NULL;
271                 }
272                 
273         }
274         
275         if (!py_result) {
276                 BPy_errors_to_report(reports);
277         } else {
278                 Py_DECREF( py_result );
279         }
280         
281         Py_DECREF(py_dict);
282         PyGILState_Release(gilstate);
283         bpy_import_main_set(NULL);
284         
285         //BPY_end_python();
286         return py_result ? 1:0;
287 }
288
289
290 /* TODO - move into bpy_space.c ? */
291 /* GUI interface routines */
292
293 /* Copied from Draw.c */
294 static void exit_pydraw( SpaceScript * sc, short err )
295 {
296         Script *script = NULL;
297
298         if( !sc || !sc->script )
299                 return;
300
301         script = sc->script;
302
303         if( err ) {
304                 BPy_errors_to_report(NULL); // TODO, reports
305                 script->flags = 0;      /* mark script struct for deletion */
306                 SCRIPT_SET_NULL(script);
307                 script->scriptname[0] = '\0';
308                 script->scriptarg[0] = '\0';
309 // XXX 2.5              error_pyscript();
310 // XXX 2.5              scrarea_queue_redraw( sc->area );
311         }
312
313 #if 0 // XXX 2.5
314         BPy_Set_DrawButtonsList(sc->but_refs);
315         BPy_Free_DrawButtonsList(); /*clear all temp button references*/
316 #endif
317
318         sc->but_refs = NULL;
319         
320         Py_XDECREF( ( PyObject * ) script->py_draw );
321         Py_XDECREF( ( PyObject * ) script->py_event );
322         Py_XDECREF( ( PyObject * ) script->py_button );
323
324         script->py_draw = script->py_event = script->py_button = NULL;
325 }
326
327 static int bpy_run_script_init(bContext *C, SpaceScript * sc)
328 {
329         if (sc->script==NULL) 
330                 return 0;
331         
332         if (sc->script->py_draw==NULL && sc->script->scriptname[0] != '\0')
333                 BPY_run_python_script(C, sc->script->scriptname, NULL, NULL);
334                 
335         if (sc->script->py_draw==NULL)
336                 return 0;
337         
338         return 1;
339 }
340
341 int BPY_run_script_space_draw(const struct bContext *C, SpaceScript * sc)
342 {
343         if (bpy_run_script_init( (bContext *)C, sc)) {
344                 PyGILState_STATE gilstate = PyGILState_Ensure();
345                 PyObject *result = PyObject_CallObject( sc->script->py_draw, NULL );
346                 
347                 if (result==NULL)
348                         exit_pydraw(sc, 1);
349                         
350                 PyGILState_Release(gilstate);
351         }
352         return 1;
353 }
354
355 // XXX - not used yet, listeners dont get a context
356 int BPY_run_script_space_listener(bContext *C, SpaceScript * sc)
357 {
358         if (bpy_run_script_init(C, sc)) {
359                 PyGILState_STATE gilstate = PyGILState_Ensure();
360                 
361                 PyObject *result = PyObject_CallObject( sc->script->py_draw, NULL );
362                 
363                 if (result==NULL)
364                         exit_pydraw(sc, 1);
365                         
366                 PyGILState_Release(gilstate);
367         }
368         return 1;
369 }
370
371 void BPY_DECREF(void *pyob_ptr)
372 {
373         Py_DECREF((PyObject *)pyob_ptr);
374 }
375
376 #if 0
377 /* called from the the scripts window, assume context is ok */
378 int BPY_run_python_script_space(const char *modulename, const char *func)
379 {
380         PyObject *py_dict, *py_result= NULL;
381         char pystring[512];
382         PyGILState_STATE gilstate;
383         
384         /* for calling the module function */
385         PyObject *py_func, 
386         
387         gilstate = PyGILState_Ensure();
388         
389         py_dict = CreateGlobalDictionary(C);
390         
391         PyObject *module = PyImport_ImportModule(scpt->script.filename);
392         if (module==NULL) {
393                 PyErr_SetFormat(PyExc_SystemError, "could not import '%s'", scpt->script.filename);
394         }
395         else {
396                 py_func = PyObject_GetAttrString(modulename, func);
397                 if (py_func==NULL) {
398                         PyErr_SetFormat(PyExc_SystemError, "module has no function '%s.%s'\n", scpt->script.filename, func);
399                 }
400                 else {
401                         Py_DECREF(py_func);
402                         if (!PyCallable_Check(py_func)) {
403                                 PyErr_SetFormat(PyExc_SystemError, "module item is not callable '%s.%s'\n", scpt->script.filename, func);
404                         }
405                         else {
406                                 py_result= PyObject_CallObject(py_func, NULL); // XXX will need args eventually
407                         }
408                 }
409         }
410         
411         if (!py_result) {
412                 BPy_errors_to_report(NULL); // TODO - reports
413         } else
414                 Py_DECREF( py_result );
415         
416         Py_XDECREF(module);
417         
418         Py_DECREF(py_dict);
419         
420         PyGILState_Release(gilstate);
421         return 1;
422 }
423 #endif
424
425 // #define TIME_REGISTRATION
426
427 #ifdef TIME_REGISTRATION
428 #include "PIL_time.h"
429 #endif
430
431 /* for use by BPY_run_ui_scripts only */
432 static int bpy_import_module(char *modname, int reload)
433 {
434         PyObject *mod= PyImport_ImportModuleLevel(modname, NULL, NULL, NULL, 0);
435         if (mod) {
436                 if (reload) {
437                         PyObject *mod_orig= mod;
438                         mod= PyImport_ReloadModule(mod);
439                         Py_DECREF(mod_orig);
440                 }
441         }
442
443         if(mod) {
444                 Py_DECREF(mod); /* could be NULL from reloading */
445                 return 0;
446         } else {
447                 return -1;
448         }
449 }
450
451 /* XXX this is temporary, need a proper script registration system for 2.5 */
452 void BPY_run_ui_scripts(bContext *C, int reload)
453 {
454 #ifdef TIME_REGISTRATION
455         double time = PIL_check_seconds_timer();
456 #endif
457         DIR *dir; 
458         struct dirent *de;
459         char *file_extension;
460         char *dirname;
461         char path[FILE_MAX];
462         char *dirs[] = {"ui", "io", NULL};
463         int a, err;
464         
465         PyGILState_STATE gilstate;
466         PyObject *sys_path;
467
468         gilstate = PyGILState_Ensure();
469         
470         // XXX - evil, need to access context
471         BPy_SetContext(C);
472         bpy_import_main_set(CTX_data_main(C));
473
474
475         sys_path= PySys_GetObject("path"); /* borrow */
476         PyList_Insert(sys_path, 0, Py_None); /* place holder, resizes the list */
477
478         for(a=0; dirs[a]; a++) {
479                 dirname= BLI_gethome_folder(dirs[a]);
480
481                 if(!dirname)
482                         continue;
483
484                 dir = opendir(dirname);
485
486                 if(!dir)
487                         continue;
488                 
489                 /* set the first dir in the sys.path for fast importing of modules */
490                 PyList_SetItem(sys_path, 0, PyUnicode_FromString(dirname)); /* steals the ref */
491                         
492                 while((de = readdir(dir)) != NULL) {
493                         /* We could stat the file but easier just to let python
494                          * import it and complain if theres a problem */
495                         err = 0;
496
497                         if (de->d_name[0] == '.') {
498                                 /* do nothing, probably .svn */
499                         }
500                         else if ((file_extension = strstr(de->d_name, ".py"))) {
501                                 /* normal py files? */
502                                 if(file_extension && file_extension[3] == '\0') {
503                                         de->d_name[(file_extension - de->d_name)] = '\0';
504                                         err= bpy_import_module(de->d_name, reload);
505                                 }
506                         }
507 #ifndef __linux__
508                         else if( BLI_join_dirfile(path, dirname, de->d_name), S_ISDIR(BLI_exists(path))) {
509 #else
510                         else if(de->d_type==DT_DIR) {
511                                 BLI_join_dirfile(path, dirname, de->d_name);
512 #endif
513                                 /* support packages */
514                                 BLI_join_dirfile(path, path, "__init__.py");
515
516                                 if(BLI_exists(path)) {
517                                         err= bpy_import_module(de->d_name, reload);
518                                 }
519                         }
520
521                         if(err==-1) {
522                                 BPy_errors_to_report(NULL);
523                                 fprintf(stderr, "unable to import %s/%s\n", dirname, de->d_name);
524                         }
525                 }
526
527                 closedir(dir);
528         }
529         
530         PyList_SetSlice(sys_path, 0, 1, NULL); /* remove the first item */
531
532         bpy_import_main_set(NULL);
533         
534         PyGILState_Release(gilstate);
535 #ifdef TIME_REGISTRATION
536         printf("script time %f\n", (PIL_check_seconds_timer()-time));
537 #endif
538 }
539
540 /* ****************************************** */
541 /* Drivers - PyExpression Evaluation */
542
543 /* for pydrivers (drivers using one-line Python expressions to express relationships between targets) */
544 PyObject *bpy_pydriver_Dict = NULL;
545
546 /* For faster execution we keep a special dictionary for pydrivers, with
547  * the needed modules and aliases. 
548  */
549 static int bpy_pydriver_create_dict(void)
550 {
551         PyObject *d, *mod;
552         
553         /* validate namespace for driver evaluation */
554         if (bpy_pydriver_Dict) return -1;
555
556         d = PyDict_New();
557         if (d == NULL) 
558                 return -1;
559         else
560                 bpy_pydriver_Dict = d;
561
562         /* import some modules: builtins, bpy, math, (Blender.noise )*/
563         PyDict_SetItemString(d, "__builtins__", PyEval_GetBuiltins());
564
565         mod = PyImport_ImportModule("math");
566         if (mod) {
567                 PyDict_Merge(d, PyModule_GetDict(mod), 0); /* 0 - dont overwrite existing values */
568                 
569                 /* Only keep for backwards compat! - just import all math into root, they are standard */
570                 PyDict_SetItemString(d, "math", mod);
571                 PyDict_SetItemString(d, "m", mod);
572                 Py_DECREF(mod);
573         } 
574         
575         /* add bpy to global namespace */
576         mod= PyImport_ImportModuleLevel("bpy", NULL, NULL, NULL, 0);
577         if (mod) {
578                 PyDict_SetItemString(bpy_pydriver_Dict, "bpy", mod);
579                 Py_DECREF(mod);
580         }
581         
582         
583 #if 0 // non existant yet
584         mod = PyImport_ImportModule("Blender.Noise");
585         if (mod) {
586                 PyDict_SetItemString(d, "noise", mod);
587                 PyDict_SetItemString(d, "n", mod);
588                 Py_DECREF(mod);
589         } else {
590                 PyErr_Clear();
591         }
592         
593         /* If there's a Blender text called pydrivers.py, import it.
594          * Users can add their own functions to this module. 
595          */
596         if (G.f & G_DOSCRIPTLINKS) {
597                 mod = importText("pydrivers"); /* can also use PyImport_Import() */
598                 if (mod) {
599                         PyDict_SetItemString(d, "pydrivers", mod);
600                         PyDict_SetItemString(d, "p", mod);
601                         Py_DECREF(mod);
602                 } else {
603                         PyErr_Clear();
604                 }
605         }
606 #endif // non existant yet
607         
608         return 0;
609 }
610
611 /* Update function, it gets rid of pydrivers global dictionary, forcing
612  * BPY_pydriver_eval to recreate it. This function is used to force
613  * reloading the Blender text module "pydrivers.py", if available, so
614  * updates in it reach pydriver evaluation. 
615  */
616 void BPY_pydriver_update(void)
617 {
618         PyGILState_STATE gilstate = PyGILState_Ensure();
619
620         if (bpy_pydriver_Dict) { /* free the global dict used by pydrivers */
621                 PyDict_Clear(bpy_pydriver_Dict);
622                 Py_DECREF(bpy_pydriver_Dict);
623                 bpy_pydriver_Dict = NULL;
624         }
625
626         PyGILState_Release(gilstate);
627
628         return;
629 }
630
631 /* error return function for BPY_eval_pydriver */
632 static float pydriver_error(ChannelDriver *driver) 
633 {
634         if (bpy_pydriver_Dict) { /* free the global dict used by pydrivers */
635                 PyDict_Clear(bpy_pydriver_Dict);
636                 Py_DECREF(bpy_pydriver_Dict);
637                 bpy_pydriver_Dict = NULL;
638         }
639
640         driver->flag |= DRIVER_FLAG_INVALID; /* py expression failed */
641         fprintf(stderr, "\nError in Driver: The following Python expression failed:\n\t'%s'\n\n", driver->expression);
642         
643         BPy_errors_to_report(NULL); // TODO - reports
644
645         return 0.0f;
646 }
647
648 /* This evals py driver expressions, 'expr' is a Python expression that
649  * should evaluate to a float number, which is returned. 
650  */
651 float BPY_pydriver_eval (ChannelDriver *driver)
652 {
653         PyObject *driver_vars=NULL;
654         PyObject *retval;
655         PyGILState_STATE gilstate;
656         
657         DriverTarget *dtar;
658         float result = 0.0f; /* default return */
659         char *expr = NULL;
660         short targets_ok= 1;
661         
662         /* sanity checks - should driver be executed? */
663         if ((driver == NULL) /*|| (G.f & G_DOSCRIPTLINKS)==0*/) 
664                 return result;
665         
666         /* get the py expression to be evaluated */
667         expr = driver->expression; 
668         if ((expr == NULL) || (expr[0]=='\0')) 
669                 return result;
670
671         gilstate = PyGILState_Ensure();
672         
673         /* init global dictionary for py-driver evaluation settings */
674         if (!bpy_pydriver_Dict) {
675                 if (bpy_pydriver_create_dict() != 0) {
676                         fprintf(stderr, "Pydriver error: couldn't create Python dictionary");
677                         PyGILState_Release(gilstate);
678                         return result;
679                 }
680         }
681         
682         /* add target values to a dict that will be used as '__locals__' dict */
683         driver_vars = PyDict_New(); // XXX do we need to decref this?
684         for (dtar= driver->targets.first; dtar; dtar= dtar->next) {
685                 PyObject *driver_arg = NULL;
686                 float tval = 0.0f;
687                 
688                 /* try to get variable value */
689                 tval= driver_get_target_value(driver, dtar);
690                 driver_arg= PyFloat_FromDouble((double)tval);
691                 
692                 /* try to add to dictionary */
693                 if (PyDict_SetItemString(driver_vars, dtar->name, driver_arg)) {
694                         /* this target failed - bad name */
695                         if (targets_ok) {
696                                 /* first one - print some extra info for easier identification */
697                                 fprintf(stderr, "\nBPY_pydriver_eval() - Error while evaluating PyDriver:\n");
698                                 targets_ok= 0;
699                         }
700                         
701                         fprintf(stderr, "\tBPY_pydriver_eval() - couldn't add variable '%s' to namespace \n", dtar->name);
702                         BPy_errors_to_report(NULL); // TODO - reports
703                 }
704         }
705         
706         /* execute expression to get a value */
707         retval = PyRun_String(expr, Py_eval_input, bpy_pydriver_Dict, driver_vars);
708         
709         /* decref the driver vars first...  */
710         Py_DECREF(driver_vars);
711         
712         /* process the result */
713         if (retval == NULL) {
714                 result = pydriver_error(driver);
715                 PyGILState_Release(gilstate);
716                 return result;
717         }
718
719         result = (float)PyFloat_AsDouble(retval);
720         Py_DECREF(retval);
721         
722         if ((result == -1) && PyErr_Occurred()) {
723                 result = pydriver_error(driver);
724                 PyGILState_Release(gilstate);
725                 return result;
726         }
727         
728         /* all fine, make sure the "invalid expression" flag is cleared */
729         driver->flag &= ~DRIVER_FLAG_INVALID;
730
731         PyGILState_Release(gilstate);
732
733         return result;
734 }