示例#1
0
文件: pyscm.c 项目: tddpirate/pyguile
static PyObject *
pyscm_PySCM_call(pyscm_PySCMObject *self, PyObject *args, PyObject *kwargs)
{
  /* Return the result of calling self with argument args */

  SCM shandle = scm_hashv_get_handle(pyscm_registration_hash,scm_long2num(self->ob_scm_index));
  if (SCM_BOOLP(shandle) && SCM_EQ_P(SCM_BOOL_F,shandle)) {
    Py_FatalError("PySCM object lost its associated SCM object");  // NOT COVERED BY TESTS
  }
  // Now:
  // SCM_CADR(shandle) is the SCM object itself
  // SCM_CDDR(shandle) is the stemplate.
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYSCM)) {
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# pyscm_PySCM_call: calling ~S with args=~S and keywords=~S; stemplate=~S\n"),scm_list_4(SCM_CADR(shandle),verbosity_repr(args),verbosity_repr(kwargs),SCM_CDDR(shandle)));
  }

  SCM sapply_func = GET_APPLY_FUNC(SCM_CDDR(shandle));
  if (SCM_EQ_P(SCM_EOL,sapply_func)) {
    if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYSCM)) {
      scm_simple_format(scm_current_output_port(),scm_makfrom0str("# pyscm_PySCM_call: raising exceptions.TypeError due to \"PySCM wraps a non-callable SCM\"\n"),SCM_EOL);
    }
    PyErr_SetString(PyExc_TypeError, "PySCM wraps a non-callable SCM");
    return(NULL);
  }

  // Process arguments.
  SCM sargs_template = GET_P2G_POSITIONAL_ARGS_TEMPLATE(SCM_CDDR(shandle));
  SCM skwargs_template = GET_P2G_KEYWORD_ARGS_TEMPLATE(SCM_CDDR(shandle));
  /*if (logical_xor(SCM_EQ_P(SCM_EOL,sargs_template),(NULL==args))
    || logical_xor(SCM_EQ_P(SCM_EOL,skwargs_template),(NULL==kwargs)))*/
  // The following allows template to exist without actual arguments.
  if ((SCM_EQ_P(SCM_EOL,sargs_template) && (NULL != args))
      || (SCM_EQ_P(SCM_EOL,skwargs_template) && (NULL != kwargs))) {
    if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYSCM)) {
      scm_simple_format(scm_current_output_port(),scm_makfrom0str("# pyscm_PySCM_call: raising exceptions.TypeError due to \"wrapped SCM does not take some of the provided arguments\"\n"),SCM_EOL);
    }
    PyErr_SetString(PyExc_TypeError, "wrapped SCM does not take some of the provided arguments");
    return(NULL);
  }

  SCM sargs = SCM_EQ_P(SCM_EOL,sargs_template) || (NULL == args)
    ? SCM_EOL : p2g_apply(args,sargs_template);
  SCM skwargs = SCM_EQ_P(SCM_EOL,skwargs_template) || (NULL == kwargs)
    ? SCM_EOL : p2g_apply(kwargs,skwargs_template);

  SCM sresult = scm_apply(sapply_func,scm_list_2(SCM_CADR(shandle),scm_list_2(sargs,skwargs)),SCM_EOL);
  SCM sresult_template = GET_G2P_RESULT_TEMPLATE(SCM_CDDR(shandle));
  if (SCM_EQ_P(SCM_EOL,sresult_template)) {
    Py_RETURN_NONE;
  }
  else {
    return(g2p_apply(sresult,sresult_template));
  }
}
示例#2
0
static void scm_conv_check(void)
{
    scm_init_guile();
    static struct {
        int version;
        char const *str;
        char const *num;
        sa_family_t exp_family;
    } tests[] = {
        { 4, "1.0.0.0", "(%d . 16777216)", AF_INET },
        { 4, "127.0.0.1", "(%d . 2130706433)", AF_INET },
        { 4, "128.10.5.255", "(%d . 2148140543)", AF_INET },
        { 6, "ff02::1", "(%d . 338963523518870617245727861364146307073)", AF_INET6 },
        { 6, "1:2:3:4::", "(%d . 5192455318486707403025865779445760)", AF_INET6 },
    };

    for (unsigned t = 0; t < NB_ELEMS(tests); t++) {
        struct ip_addr addr;
        ip_addr_ctor_from_str(&addr, tests[t].str, strlen(tests[t].str), tests[t].version);
        SCM ip = scm_from_ip_addr(&addr);
        SCM str = scm_simple_format(SCM_BOOL_F, scm_from_latin1_string("~a"), scm_cons(ip, SCM_EOL));
        char buf[256];
        size_t len = scm_to_locale_stringbuf(str, buf, sizeof(buf));
        assert(len < sizeof(buf));
        buf[len] = '\0';
        char expected[256];
        snprintf(expected, sizeof(expected), tests[t].num, tests[t].exp_family);

        printf("%s -> '%s' (expected '%s')\n", tests[t].str, buf, expected);
        assert(0 == strcmp(expected, buf));
    }
}
示例#3
0
文件: pyscm.c 项目: tddpirate/pyguile
static int
pyscm_PySCM_setattr(pyscm_PySCMObject *self, char *name, PyObject *v)
{
  /* Set attribute 'name' to value 'v'. v==NULL means delete */
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYSCM)) {
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# pyscm_PySCM_setattr: trying to set attribute=~S from pobj=~S to value ~S\n"),scm_list_3(scm_makfrom0str(name),verbosity_repr((PyObject *)self),verbosity_repr(v)));
  }
  SCM sobj_keyword;
  SCM sattr_vector = retrieve_sattr_vector(self,name,&sobj_keyword);
  if (SCM_UNBNDP(sattr_vector)) {
    // Attribute error exception was raised by retrieve_sattr_vector().
    return(-1);
  }

  SCM ssetattr_func = GET_H_SETATTR_FUNC(sattr_vector);
  if (SCM_EQ_P(SCM_EOL,ssetattr_func)) {
    PyErr_SetString(PyExc_AttributeError, name);
    return(-1);
  }

  if (NULL != v) {
    SCM sval = p2g_apply(v,
			 GET_H_P2G_SETATTR_TEMPLATE(sattr_vector));
    scm_append_x(scm_list_2(sobj_keyword,sval));
  }

  SCM sresult = scm_apply(ssetattr_func,sobj_keyword,SCM_EOL);
  return(SCM_EQ_P(SCM_BOOL_F,sresult) ? (-1) : 0);
}
示例#4
0
文件: pyscm.c 项目: tddpirate/pyguile
static long
pyscm_PySCM_hash(pyscm_PySCMObject *self)
{
  /* Return a hash of self (or -1) */
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYSCM)) {
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# pyscm_PySCM_hash: hash is ~S\n"),scm_list_1(scm_long2num(self->ob_scm_index)));
  }
  return(self->ob_scm_index);
}
示例#5
0
文件: pyscm.c 项目: tddpirate/pyguile
// Unwrap a pyscm_PySCMObject instance and get from it the original
// SCM object.  If the object is not a pyscm_PySCMObject or does not
// wrap a SCM object, raise an error.
SCM
unwrap_pyscm_object(PyObject *pobj)
{
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYSCM)) {
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# unwrap_pyscm_object: trying to unwrap pobj=~S\n"),scm_list_1(verbosity_repr(pobj)));
  }

  if (!PySCMObject_Check(pobj)) {
    Py_FatalError("Trying to pyscm-unwrap a non-PySCM");
  }
  SCM shandle = scm_hashv_get_handle(pyscm_registration_hash,scm_long2num(((pyscm_PySCMObject *)pobj)->ob_scm_index));
  return(SCM_CADR(shandle));
}
示例#6
0
文件: pyscm.c 项目: tddpirate/pyguile
static PyObject *
pyscm_PySCM_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
  pyscm_PySCMObject *self;
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_GC_PYSCM)) {
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# pyscm_PySCM_new: was called\n"),SCM_EOL);
  }
  self = (pyscm_PySCMObject *)type->tp_alloc(type,0);
  if (NULL != self) {
    self->ob_scm_index = 0;
  }
  return((PyObject *)self);
}
示例#7
0
文件: pyscm.c 项目: tddpirate/pyguile
static void
pyscm_PySCM_dealloc(pyscm_PySCMObject *self)
{
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_GC_PYSCM)) {
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# pyscm_PySCM_dealloc: deallocating PySCMObject with hash ~S\n"),scm_list_1(scm_long2num(self->ob_scm_index)));
  }
  if (0 != self->ob_scm_index) {
    // Unregister the associated SCM from the hash table.
    SCM shashkey = scm_long2num(self->ob_scm_index);
    scm_hashv_remove_x(pyscm_registration_hash,shashkey);
    // If ob_scm_index is zero, no SCM was associated yet with
    // this PySCM instance.
  }
  self->ob_type->tp_free((PyObject*)self);
}
示例#8
0
文件: pyscm.c 项目: tddpirate/pyguile
// Create a pyscm_PySCMObject instance, which wraps sobj and associates
// with it with template for data conversions when python accesses data
// and functions/methods associated with sobj.
PyObject *
wrap_scm(SCM sobj,SCM stemplate)
{
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYSCM)) {
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# wrap_scm: was called to wrap ~S\n"),scm_list_1(sobj));
  }
  pyscm_PySCMObject *pwrapper = PyObject_New(pyscm_PySCMObject,&pyscm_PySCMType);
  if (NULL == pwrapper) {
    scm_memory_error("wrap_scm");  // NOT COVERED BY TESTS
  }
  //PyObject_Init(pwrapper,&pyscm_PySCMType);  // Is it needed or does PyObject_New() take care of it?
  //if (NULL == pwrapper) {
  //  scm_misc_error("wrap_scm","could not wrap object ~S with PySCM when using conversion template ~S",
  //		   scm_list_2(sobj,stemplate));
  //}
  else {
    SCM sconsed = scm_cons(sobj,stemplate);
    SCM shashkey = scm_long2num(++pyscm_registration_index);
    scm_hashv_create_handle_x(pyscm_registration_hash,shashkey,sconsed);
    pwrapper->ob_scm_index = pyscm_registration_index;
    return((PyObject *)pwrapper);
  }
}
示例#9
0
文件: pyscm.c 项目: tddpirate/pyguile
static PyObject *
pyscm_PySCM_getattr(pyscm_PySCMObject *self, char *name)
{
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYSCM)) {
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# pyscm_PySCM_getattr: trying to get attribute=~S from pobj=~S\n"),scm_list_2(scm_makfrom0str(name),verbosity_repr((PyObject *)self)));
  }
  SCM sobj_keyword;
  SCM sattr_vector = retrieve_sattr_vector(self,name,&sobj_keyword);
  if (SCM_UNBNDP(sattr_vector)) {
    // Attribute error exception was raised by retrieve_sattr_vector().
    return(NULL);
  }

  SCM sgetattr_func = GET_H_GETATTR_FUNC(sattr_vector);
  if (SCM_EQ_P(SCM_EOL,sgetattr_func)) {
    PyErr_SetString(PyExc_AttributeError, name);
    return(NULL);
  }
  SCM stemplate = GET_H_G2P_GETATTR_TEMPLATE(sattr_vector);

  SCM sresult = scm_apply(sgetattr_func,sobj_keyword,SCM_EOL);
  return(g2p_apply(sresult,stemplate));
}
示例#10
0
// python_apply implements the function call:
// (python-apply ("module.submodule" 'obj 'func)
//               (arg1 arg2 arg3)
//               (('keyword1 . val4) ('keyword2 . val5))
//               sargtemplate
//               skwtemplate)
// which is the basic way to invoke a Python function.
//
// sfunc specifies the function to be invoked.  The possibilities
// are:
//   String - denotes a top level function ("func" means __main__.func).
//   pysmob - assumed to be a callable object.
//   ("module.submodule" ...) - a List of strings/symbols/keywords
//     in which the first item must be a string denotes:
//     Module "module.submodule" (which should have already been imported
//       using python-import)
//     followed by name of object in that module, followed by attribute,...,
//     until the final callable attribute.
//   (pysmob ...) - a List starting with pysmob followed by
//     strings/symbols/keywords - processed similarly, except that the
//     pysmob stands for the module.
// sarg is a list of arguments (in Python it's *arg)
// skw is an alist (in Python it's **kw).
// sargtemplate - specifies how to convert sarg - optional argument.
// skwtemplate - specifies how to convert skw - optional argument.
// srestemplate - specifies how to convert the result back into
//     SCM - optional argument.
SCM
python_apply(SCM sfunc, SCM sarg, SCM skw,
	     SCM sargtemplate, SCM skwtemplate,	SCM srestemplate)
{
  PyObject *pfunc = NULL;
  PyObject *parg = NULL;
  PyObject *pkw = NULL;

  PyObject *pfuncobj = NULL;
  PyObject *pres = NULL;
  SCM sres = SCM_UNDEFINED;

  if (SCM_UNBNDP(sargtemplate)) { //(sargtemplate == SCM_UNDEFINED) // SCM_UNSPECIFIED
    sargtemplate = sargtemplate_default;
  }
  if (SCM_UNBNDP(skwtemplate)) {
    skwtemplate = skwtemplate_default;
  }
  if (SCM_UNBNDP(srestemplate)) {
    srestemplate = srestemplate_default;
  }

  // Retrieve the function object.

  pfunc = guile2python(sfunc,SCM_UNSPECIFIED);
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYTHON_APPLY)) {
    char *preprfunc = PyString_AsString(PyObject_Repr(pfunc));
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# python_apply: decoded pfunc ~S\n"),scm_list_1(scm_makfrom0str(preprfunc)));
  }
  if (NULL == pfunc) {
    scm_misc_error("python-apply","conversion failure (~S)",
		   scm_list_1(SCM_CDR(sfunc)));
  }
  // If it is a string, prepend it with "__main__".
  if (PyString_CheckExact(pfunc)) {
    // Convert it into a List of two items, to unify
    // subsequent treatment.
    PyObject *plist = PyList_New(2);
    if (NULL == plist) {
      Py_DECREF(pfunc);  // NOT COVERED BY TESTS
      scm_memory_error("python-apply");  // NOT COVERED BY TESTS
    }
    if (-1 == PyList_SetItem(plist,0,PyString_FromString("__main__"))) {
      Py_DECREF(pfunc);  // NOT COVERED BY TESTS
      Py_DECREF(plist);  // NOT COVERED BY TESTS
      scm_misc_error("python-apply","PyList_SetItem 0 failure (~S)",  // NOT COVERED BY TESTS
		     scm_list_1(SCM_CAR(sfunc)));
    }
    if (-1 == PyList_SetItem(plist,1,pfunc)) {
      Py_DECREF(pfunc);  // NOT COVERED BY TESTS
      Py_DECREF(plist);  // NOT COVERED BY TESTS
      scm_misc_error("python-apply","PyList_SetItem 1 failure (~S)",  // NOT COVERED BY TESTS
		     scm_list_1(SCM_CAR(sfunc)));
    }
    pfunc = plist;  // plist stole previous pfunc's value's reference.
  }
  else if (IS_PYSMOBP(sfunc)) {
    // We check the SCM object because guile2python() destroys
    // the indication whether the SCM was originally a pysmob, when it
    // converts it into PyObject.
    PyObject *plist1 = PyList_New(1);
    if (NULL == plist1) {
      Py_DECREF(pfunc);  // NOT COVERED BY TESTS
      scm_memory_error("python-apply");  // NOT COVERED BY TESTS
    }
    if (-1 == PyList_SetItem(plist1,0,pfunc)) {
      Py_DECREF(pfunc);  // NOT COVERED BY TESTS
      Py_DECREF(plist1);  // NOT COVERED BY TESTS
      scm_misc_error("python-apply","PyList_SetItem 0 failure (~S)",  // NOT COVERED BY TESTS
		     scm_list_1(SCM_CAR(sfunc)));
    }
    pfunc = plist1;  // plist1 stole previous pfunc's value's reference.
    // Now pfunc is an 1-member list, and this member is
    // expected to be callable.
  }
  else if (!PyList_CheckExact(pfunc)) {
    // Now, the qualified function name must be a proper list.
    scm_wrong_type_arg("python-apply",SCM_ARG1,sfunc);
  }

  if (1 > PyList_Size(pfunc)) {
    // The list must consist of at least one callable module name/object.
    scm_misc_error("python-apply",
		   "first argument must contain at least one callable object (~S)",
		   scm_list_1(SCM_CAR(sfunc)));
  }

  if (PyString_CheckExact(PyList_GetItem(pfunc,0))) {
    // If it is a string, we assume it to be the name of a module
    // which has already been imported.
    // Due to the existence of dots, 
    // we don't allow it to be symbol or keyword.

    pfuncobj = PyImport_AddModule(PyString_AsString(PyList_GetItem(pfunc,0)));
    if (NULL == pfuncobj) {
      Py_DECREF(pfunc);
      scm_misc_error("python-apply",
		     "module ~S could not be accessed - probably not imported",
		     scm_list_1(SCM_CAR(sfunc)));
    }
    Py_INCREF(pfuncobj);
  }
  else {
    // We assume that it is a callable or object with attributes.
    pfuncobj = PyList_GetItem(pfunc,0);
    if (NULL == pfuncobj) {
      Py_DECREF(pfunc);
      scm_misc_error("python-apply",
		     "could not access object starting ~S",
		     scm_list_1(sfunc));
    }
    Py_INCREF(pfuncobj);
  }

  // Here we dereference attributes (if any).
  int listsize = PyList_Size(pfunc);
  int ind;

  for (ind = 1; ind < listsize; ++ind) {
    PyObject *pnextobj = PyObject_GetAttr(pfuncobj,PyList_GetItem(pfunc,ind));
    if (NULL == pnextobj) {
      PyObject *pexception = PyErr_Occurred();
      Py_DECREF(pfunc);
      Py_DECREF(pfuncobj);
      if (pexception) {
	PyErr_Clear();
	// An AttributeError exception is expected here.
	if (!PyErr_GivenExceptionMatches(pexception,PyExc_AttributeError)) {
	  PyObject *prepr = PyObject_Repr(pexception);
	  if (NULL == prepr) {
	    scm_misc_error("python-apply",
			   "python exception - could not be identified",
			   SCM_UNSPECIFIED);
	  }
	  else {
	    int strlength = PyString_Size(prepr);
	    char *pstr = PyString_AsString(prepr);
	    SCM srepr = scm_list_1(scm_mem2string(pstr,strlength));
	    Py_DECREF(prepr);
	    scm_misc_error("python-apply",
			   "Python exception (~A) while dereferencing object attribute",
			   srepr);
	  }
	}
	// else we got the expected AttributeError exception.
      }
      // else we got NULL==pnextobj without Python exception.
      scm_misc_error("python-apply",
		     "could not dereference ~Ath level attribute in ~S",
		     scm_list_2(scm_long2num(ind),sfunc));
    }
    Py_INCREF(pnextobj);
    Py_DECREF(pfuncobj);
    pfuncobj = pnextobj;
  }
  Py_DECREF(pfunc);  // We do not need it anymore.  pfuncobj points at
                     // the function actually to be invoked.
  if (!PyCallable_Check(pfuncobj)) {
    Py_DECREF(pfuncobj);
    scm_misc_error("python-apply","function denoted by ~S is not callable",scm_list_1(sfunc));
  }

  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYTHON_APPLY)) {
    char *preprfuncobj = PyString_AsString(PyObject_Repr(pfuncobj));
    scm_simple_format(scm_current_output_port(),
		      scm_makfrom0str("# python_apply: decoded function actually to be invoked: ~S\n"),
		      scm_list_1(scm_makfrom0str(preprfuncobj)));
  }

  // Retrieve positional arguments

  parg = g2p_apply(sarg,sargtemplate);
  if (NULL == parg) {
    Py_DECREF(pfuncobj);
    scm_misc_error("python-apply","positional arguments conversion failure (~S)",
		   scm_list_1(sarg));
  }
  // Validate that it is indeed a tuple.
  if (!PyTuple_CheckExact(parg)) {
    Py_DECREF(pfuncobj);
    Py_DECREF(parg);
    scm_wrong_type_arg("python-apply",SCM_ARG2,sarg);
  }
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYTHON_APPLY)) {
    char *pposarg = PyString_AsString(PyObject_Repr(parg));
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# python_apply: decoded positional arguments ~S\n"),scm_list_1(scm_makfrom0str(pposarg)));
  }

  // Retrieve keyword arguments.

  pkw = guileassoc2pythondict(skw,skwtemplate);
  if (NULL == pkw) {
    // Seems that PyDict_CheckExact() does not handle NULL argument gracefully.
     Py_DECREF(pfuncobj);
     Py_DECREF(parg);
     scm_misc_error("python-apply","keyword arguments conversion failure (~S)",
		    scm_list_1(skw));
  }
  if (!PyDict_CheckExact(pkw)) {
     Py_DECREF(pfuncobj);
     Py_DECREF(parg);
     Py_DECREF(pkw);
     scm_misc_error("python-apply",
		    "keyword arguments (~S) not properly converted into Python Dict",
		    scm_list_1(skw));
  }
  if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYTHON_APPLY)) {
    char *pkwarg = PyString_AsString(PyObject_Repr(pkw));
    scm_simple_format(scm_current_output_port(),scm_makfrom0str("# python_apply: decoded keyword arguments ~S\n"),scm_list_1(scm_makfrom0str(pkwarg)));
  }

  // Ready to invoke the function.

  pres = PyEval_CallObjectWithKeywords(pfuncobj,parg,pkw);
  PyObject *pexception = PyErr_Occurred();
  if (pexception) {
    PyObject *prepr = PyObject_Repr(pexception);
    Py_DECREF(pfuncobj);
    Py_DECREF(parg);
    Py_DECREF(pkw);
    Py_XDECREF(pres);
    PyErr_Clear();
    if (NULL == prepr) {
      scm_misc_error("python-apply",
		     "python exception - could not be identified",
		     SCM_UNSPECIFIED);
    }
    else {
      int strlength = PyString_Size(prepr);
      char *pstr = PyString_AsString(prepr);
      SCM srepr = scm_list_1(scm_mem2string(pstr,strlength));
      Py_DECREF(prepr);
      scm_misc_error("python-apply","Python exception: ~A",
		     srepr);
    }
  }
  if (NULL != pres) {
    sres = p2g_apply(pres,srestemplate);
    if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYTHON_APPLY)) {
      char *presstr = PyString_AsString(PyObject_Repr(pres));
      scm_simple_format(scm_current_output_port(),scm_makfrom0str("# python_apply: decoded results:\n#     Python: ~S\n#     Scheme: ~S\n"),scm_list_2(scm_makfrom0str(presstr),sres));
    }
  }
  else {
    // else sres remains SCM_UNDEFINED.
    if (pyguile_verbosity_test(PYGUILE_VERBOSE_PYTHON_APPLY)) {
      scm_simple_format(scm_current_output_port(),scm_makfrom0str("# python_apply: Python code returned <NULL>\n"),SCM_EOL);
    }
  }
  return(sres);
}
示例#11
0
文件: scm2py.c 项目: rlutz/geda-gaf
PyObject *scm2py(SCM value)
{
	if (value == NULL)
		return NULL;
	if (value == SCM_UNSPECIFIED) {
		Py_INCREF(Py_None);
		return Py_None;
	}
	if (scm_is_exact_integer(value))
		return PyInt_FromLong(scm_to_long(value));
	if (scm_is_real(value))
		return PyFloat_FromDouble(scm_to_double(value));
	if (scm_is_bool(value)) {
		PyObject *result = scm_to_bool(value) ? Py_True : Py_False;
		Py_INCREF(result);
		return result;
	}
	if (value == SCM_EOL)
		return PyTuple_New(0);
	if (scm_is_string(value)) {
		size_t len = 0;
		char *s = scm_to_utf8_stringn(value, &len);
		PyObject *result = PyUnicode_FromStringAndSize(s, len);
		free(s);
		return result;
	}
	if (scm_is_pair(value)) {
		unsigned int len = scm_to_uint(scm_length(value));
		PyObject *result = PyTuple_New(len);
		scm_dynwind_begin(0);
		scm_dynwind_unwind_handler(
			(void (*)(void *))Py_DecRef, result, 0);
		unsigned int i;
		for (i = 0; i < len; i++) {
			PyObject *item = scm2py(scm_car(value));
			if (item == NULL) {
				scm_dynwind_end();
				Py_DECREF(result);
				return NULL;
			}
			PyTuple_SET_ITEM(result, i, item);
			value = scm_cdr(value);
		}
		scm_dynwind_end();
		return result;
	}
	if (scm_to_bool(scm_procedure_p(value))) {
		SCM ptr = scm_assq_ref(gsubr_alist, value);
		if (!scm_is_false(ptr)) {
			PyObject *result = scm_to_pointer(ptr);
			Py_INCREF(result);
			return result;
		}
		Procedure *result =
			(Procedure *)ProcedureType.tp_alloc(&ProcedureType, 0);
		if (result == NULL)
			return NULL;
		result->proc = value;
		return (PyObject *)result;
	}

	char *msg = scm_to_utf8_stringn(
		scm_simple_format(
			SCM_BOOL_F,
			scm_from_utf8_string(
				"Guile expression ~S doesn't have a "
				"corresponding Python value"),
			scm_list_1(value)), NULL);
	PyErr_SetString(PyExc_TypeError, msg);
	free(msg);
	return NULL;
}