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ninerniner
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Handle exceptions raised in Python or Perl code correctly
We now handle user exceptions, invalid function or method names and passing exceptions from Perl through Python back to Perl.
1 parent 688a38f commit 09ad48b

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3 files changed

+174
-19
lines changed

3 files changed

+174
-19
lines changed

‎lib/Inline/Python.pm6

Lines changed: 23 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -163,6 +163,9 @@ sub py_inc_ref(OpaquePointer)
163163
sub py_getattr(OpaquePointer, Str)
164164
returns OpaquePointer { ... }
165165
native(&py_getattr);
166+
sub py_fetch_error(CArray[OpaquePointer], CArray[OpaquePointer], CArray[OpaquePointer], CArray[OpaquePointer])
167+
{ ... }
168+
native(&py_fetch_error);
166169

167170
my $objects = ObjectKeeper.new;
168171

@@ -310,39 +313,48 @@ method !setup_arguments(@args) {
310313
return $tuple;
311314
}
312315

316+
method handle_python_exception() is hidden_from_backtrace {
317+
my @exception := CArray[OpaquePointer].new();
318+
@exception[$_] = OpaquePointer for ^4;
319+
py_fetch_error(@exception);
320+
my $ex_type = @exception[0];
321+
my $ex_message = @exception[3];
322+
if $ex_type {
323+
my $message = self.py_to_p6($ex_message);
324+
@exception[$_] and py_dec_ref(@exception[$_]) for ^4;
325+
die $message;
326+
}
327+
}
328+
313329
multi method run($python, :$eval!) {
314330
my $res = py_eval($python, 0);
331+
self.handle_python_exception();
315332
self.py_to_p6($res);
316333
}
317334

318335
multi method run($python, :$file) {
319336
my $res = py_eval($python, 1);
337+
self.handle_python_exception();
320338
self.py_to_p6($res);
321-
CATCH {
322-
default {
323-
warn $_;
324-
die $_;
325-
}
326-
}
327339
}
328340

329341
method call(Str $package, Str $function, *@args) {
330342
my $py_retval = py_call_function($package, $function, self!setup_arguments(@args));
331-
return unless defined $py_retval;
343+
self.handle_python_exception();
332344
my \retval = self.py_to_p6($py_retval);
333345
return retval;
334346
}
335347

336348
multi method invoke(OpaquePointer $obj, Str $method, *@args) {
337349
my $py_retval = py_call_method($obj, $method, self!setup_arguments(@args));
338-
return unless defined $py_retval;
350+
self.handle_python_exception();
339351
my \retval = self.py_to_p6($py_retval);
340352
py_dec_ref($py_retval);
341353
return retval;
342354
}
343355
multi method invoke(PythonParent $p6obj, OpaquePointer $obj, Str $method, *@args) {
344356
my $py_retval = py_call_method_inherited(self.p6_to_py($p6obj), $obj, $method, self!setup_arguments(@args));
345-
return unless defined $py_retval;
357+
self.handle_python_exception();
346358
my \retval = self.py_to_p6($py_retval);
347359
py_dec_ref($py_retval);
348360
return retval;
@@ -359,8 +371,7 @@ method BUILD {
359371
return self.p6_to_py(retvals);
360372
CATCH {
361373
default {
362-
warn $_;
363-
nativecast(CArray[OpaquePointer], $err)[0] = self.p6_to_py($_);
374+
nativecast(CArray[OpaquePointer], $err)[0] = self.p6_to_py($_.Str());
364375
return OpaquePointer;
365376
}
366377
}
@@ -371,7 +382,7 @@ method BUILD {
371382
return self.p6_to_py(retvals);
372383
CATCH {
373384
default {
374-
nativecast(CArray[OpaquePointer], $err)[0] = self.p6_to_p5($_);
385+
nativecast(CArray[OpaquePointer], $err)[0] = self.p6_to_py($_.Str());
375386
return OpaquePointer;
376387
}
377388
}

‎pyhelper.c

Lines changed: 47 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -51,11 +51,6 @@ PyObject *py_eval(const char* p, int type) {
5151
? Py_file_input
5252
: Py_single_input;
5353
py_result = PyRun_String(p, context, globals, locals);
54-
if (!py_result) {
55-
PyErr_Print();
56-
printf("Error -- py_eval raised an exception");
57-
return NULL;
58-
}
5954
return py_result;
6055
}
6156

@@ -203,29 +198,64 @@ PyObject *py_call_function(char *pkg, char *name, PyObject *args) {
203198
PyObject * const func = PyMapping_GetItemString(dict, name);
204199
PyObject *py_retval = NULL;
205200

201+
if (func == NULL) {
202+
PyErr_Format(PyExc_NameError, "name '%s' is not defined", name);
203+
goto cleanup;
204+
}
205+
206206
py_retval = PyObject_CallObject(func, args);
207+
207208
Py_DECREF(func);
209+
cleanup:
208210
Py_DECREF(args);
209211

210212
return py_retval;
211213
}
212214

215+
void py_fetch_error(PyObject **exception) {
216+
/* ex_type, ex_value, ex_trace, ex_message */
217+
PyErr_Fetch(&exception[0], &exception[1], &exception[2]);
218+
PyErr_NormalizeException(&exception[0], &exception[1], &exception[2]);
219+
exception[3] = PyObject_Unicode(exception[1]); /* new reference */
220+
}
221+
222+
void py_raise_missing_method(PyObject *obj, char *name) {
223+
PyObject *class = PyObject_GetAttrString(obj, "__class__");
224+
PyObject *class_name = PyObject_GetAttrString(class, "__name__");
225+
char *c_class_name = PyString_AsString(class_name);
226+
PyErr_Format(PyExc_NameError, "%s instance has no attribute '%s'", c_class_name, name);
227+
Py_DECREF(class_name);
228+
Py_DECREF(class);
229+
}
230+
213231
PyObject *py_call_method(PyObject *obj, char *name, PyObject *args) {
214232
PyObject *method = PyObject_GetAttrString(obj, name);
233+
if (method == NULL) {
234+
py_raise_missing_method(obj, name);
235+
goto cleanup;
236+
}
215237
PyObject *py_retval = PyObject_CallObject(method, args);
216238
Py_DECREF(method);
239+
240+
cleanup:
217241
Py_DECREF(args);
218242

219243
return py_retval;
220244
}
221245

222246
PyObject *py_call_method_inherited(PyObject *p6obj, PyObject *obj, char *name, PyObject *args) {
223247
PyObject *method = PyObject_GetAttrString(obj, name);
248+
if (method == NULL) {
249+
py_raise_missing_method(obj, name);
250+
goto cleanup;
251+
}
224252
PyObject *function = PyMethod_Function(method);
225253
PyObject *inherited_method = PyMethod_New(function, p6obj, perl6object);
226254
PyObject *py_retval = PyObject_CallObject(inherited_method, args);
227255
Py_DECREF(method);
228256
Py_DECREF(inherited_method);
257+
258+
cleanup:
229259
Py_DECREF(args);
230260

231261
return py_retval;
@@ -234,23 +264,33 @@ PyObject *py_call_method_inherited(PyObject *p6obj, PyObject *obj, char *name, P
234264
static PyObject *perl6_call(PyObject *self, PyObject *args) {
235265
PyObject * const index = PySequence_GetItem(args, 0);
236266
PyObject * const params = PySequence_GetItem(args, 1);
267+
PyObject * error = NULL;
237268

238-
PyObject *retval = call_p6_object(PyInt_AsLong(index), params, NULL);
269+
PyObject *retval = call_p6_object(PyInt_AsLong(index), params, &error);
270+
if (error != NULL) {
271+
PyErr_SetObject(PyExc_Exception, error);
272+
return NULL;
273+
}
239274
return retval;
240275
}
241276

242277
static PyObject *perl6_invoke(PyObject *self, PyObject *args) {
243278
PyObject * const index = PySequence_GetItem(args, 0);
244279
PyObject * const name = PySequence_GetItem(args, 1);
245280
PyObject * const params = PySequence_GetItem(args, 2);
281+
PyObject * error = NULL;
246282

247283
Py_ssize_t length;
248284
char * buf;
249285
PyString_AsStringAndSize(name, &buf, &length);
250286
char * const name_str = calloc(sizeof(char), length + 1);
251287
memcpy(name_str, buf, length);
252288

253-
PyObject *retval = call_p6_method(PyInt_AsLong(index), name_str, params, NULL);
289+
PyObject *retval = call_p6_method(PyInt_AsLong(index), name_str, params, &error);
290+
if (error != NULL) {
291+
PyErr_SetObject(PyExc_Exception, error);
292+
return NULL;
293+
}
254294
return retval;
255295
}
256296

‎t/exceptions.t

Lines changed: 104 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,104 @@
1+
#!/usr/bin/env perl6
2+
3+
use v6;
4+
use Test;
5+
use Inline::Python;
6+
7+
my $py = Inline::Python.new();
8+
{
9+
try $py.run(q:heredoc/PYTHON/);
10+
raise Exception(u"foo")
11+
PYTHON
12+
ok 1, 'survived Python exception';
13+
ok $!.isa('X::AdHoc'), 'got an exception';
14+
ok $!.Str() ~~ m/foo/, 'exception message found';
15+
}
16+
{
17+
$py.run(q:heredoc/PYTHON/);
18+
def perish():
19+
raise Exception(u"foo")
20+
PYTHON
21+
try $py.call('__main__', 'perish');
22+
ok 1, 'survived Python exception in function call';
23+
ok $!.isa('X::AdHoc'), 'got an exception from function call';
24+
ok $!.Str() ~~ m/foo/, 'exception message found from function call';
25+
}
26+
{
27+
$py.run(q:heredoc/PYTHON/);
28+
class Foo:
29+
def depart(self):
30+
raise Exception(u"foo")
31+
PYTHON
32+
my $foo = $py.call('__main__', 'Foo');
33+
$foo.depart;
34+
CATCH {
35+
ok 1, 'survived Python exception in method call';
36+
when X::AdHoc {
37+
ok $_.isa('X::AdHoc'), 'got an exception from method call';
38+
ok $_.Str() ~~ m/foo/, 'exception message found from method call';
39+
}
40+
}
41+
}
42+
{
43+
$py.call('__main__', 'non_existing');
44+
CATCH {
45+
ok 1, 'survived calling missing Python function';
46+
when X::AdHoc {
47+
ok $_.isa('X::AdHoc'), 'got an exception for calling a missing function';
48+
is $_.Str(), "name 'non_existing' is not defined", 'exception message found for missing function';
49+
}
50+
}
51+
}
52+
{
53+
$py.run(q:heredoc/PYTHON/);
54+
class Foo:
55+
pass
56+
PYTHON
57+
my $foo = $py.call('__main__', 'Foo');
58+
$foo.non_existing;
59+
CATCH {
60+
ok 1, 'survived Python missing method';
61+
when X::AdHoc {
62+
ok $_.isa('X::AdHoc'), 'got an exception for calling missing method';
63+
is $_.Str(), "Foo instance has no attribute 'non_existing'", 'exception message found for calling missing method';
64+
}
65+
}
66+
}
67+
68+
69+
class Foo {
70+
method depart {
71+
die "foo";
72+
}
73+
}
74+
75+
$py.run(q:heredoc/PYTHON/);
76+
import logging
77+
def test_foo(foo):
78+
try:
79+
foo.depart()
80+
except Exception, e:
81+
logging.warn(e)
82+
return e.message
83+
PYTHON
84+
85+
is $py.call('__main__', 'test_foo', Foo.new), 'foo';
86+
87+
{
88+
$py.run(q:heredoc/PYTHON/);
89+
def pass_through(foo):
90+
foo.depart()
91+
PYTHON
92+
$py.call('__main__', 'pass_through', Foo.new);
93+
CATCH {
94+
ok 1, 'P6 exception made it through Python code';
95+
when X::AdHoc {
96+
ok $_.isa('X::AdHoc'), 'got an exception from method call';
97+
ok $_.Str() ~~ m/foo/, 'exception message found from method call';
98+
}
99+
}
100+
}
101+
102+
done;
103+
104+
# vim: ft=perl6

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