[GR-12657] BaseException should allow set __traceback__.

PullRequest: graalpython/290

Author: ppisl

graalpython/com.oracle.graal.python.test/src/graalpytest.py

@@ -158,6 +158,15 @@ def assertSequenceEqual(self, expected, actual, msg=None):
         for expected_value in expected:
             assert expected_value == next(actual_iter), msg
 
+    def assertIsInstance(self, obj, cls, msg=None):
+        """Same as self.assertTrue(isinstance(obj, cls)), with a nicer
+        default message."""
+        if not isinstance(obj, cls):
+            message = msg
+            if msg is None:
+                message = '%s is not an instance of %r' % (obj, cls)
+            assert False, message
+
     class assertRaises():
         def __init__(self, exc_type, function=None, *args, **kwargs):
             self.function = function

graalpython/com.oracle.graal.python.test/src/tests/test_exception.py

@@ -0,0 +1,52 @@
+# Copyright (c) 2018, Oracle and/or its affiliates.
+# Copyright (C) 1996-2017 Python Software Foundation
+#
+# Licensed under the PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
+
+import unittest
+import sys
+
+class ExceptionTests(unittest.TestCase):
+
+    def testInvalidTraceback(self):
+        try:
+            Exception().__traceback__ = 5
+        except TypeError as e:
+            self.assertIn("__traceback__ must be a traceback", str(e))
+        else:
+            self.fail("No exception raised")
+
+    def testNoneClearsTracebackAttr(self):
+        try:
+            raise IndexError(4)
+        except:
+            tb = sys.exc_info()[2]
+
+        e = Exception()
+        e.__traceback__ = tb
+        e.__traceback__ = None
+        self.assertEqual(e.__traceback__, None)
+
+    def testWithTraceback(self):
+        try:
+            raise IndexError(4)
+        except:
+            tb = sys.exc_info()[2]
+
+        e = BaseException().with_traceback(tb)
+        self.assertIsInstance(e, BaseException)
+        # TODO this dosn't work yet
+        #self.assertEqual(e.__traceback__, tb)
+
+        e = IndexError(5).with_traceback(tb)
+        self.assertIsInstance(e, IndexError)
+        # TODO this dosn't work yet
+        #self.assertEqual(e.__traceback__, tb)
+
+        class MyException(Exception):
+            pass
+
+        e = MyException().with_traceback(tb)
+        self.assertIsInstance(e, MyException)
+        # TODO this dosn't work yet
+        #self.assertEqual(e.__traceback__, tb)

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/exception/BaseExceptionBuiltins.java

@@ -49,10 +49,12 @@
 import com.oracle.graal.python.nodes.function.PythonBuiltinNode;
 import com.oracle.graal.python.nodes.function.builtins.PythonUnaryBuiltinNode;
 import com.oracle.graal.python.nodes.object.GetLazyClassNode;
+import com.oracle.graal.python.runtime.exception.PythonErrorType;
 import com.oracle.graal.python.runtime.formatting.ErrorMessageFormatter;
 import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.dsl.Cached;
+import com.oracle.truffle.api.dsl.Fallback;
 import com.oracle.truffle.api.dsl.GenerateNodeFactory;
 import com.oracle.truffle.api.dsl.NodeFactory;
 import com.oracle.truffle.api.dsl.Specialization;
@@ -178,13 +180,31 @@ public boolean suppressContext(@SuppressWarnings("unused") PBaseException self)
         }
     }
 
-    @Builtin(name = __TRACEBACK__, fixedNumOfPositionalArgs = 1, isGetter = true)
+    @Builtin(name = __TRACEBACK__, minNumOfPositionalArgs = 1, maxNumOfPositionalArgs = 2, isGetter = true, isSetter = true)
     @GenerateNodeFactory
     public abstract static class TracebackNode extends PythonBuiltinNode {
 
+        @Specialization(guards = "isNoValue(tb)")
+        public Object getTraceback(PBaseException self, @SuppressWarnings("unused") Object tb) {
+            PTraceback traceback = self.getTraceback(factory());
+            return traceback == null ? PNone.NONE : traceback;
+        }
+
         @Specialization
-        public Object traceback(PBaseException self) {
-            return self.getTraceback(factory());
+        public Object setTraceback(PBaseException self, @SuppressWarnings("unused") PNone tb) {
+            self.clearTraceback();
+            return PNone.NONE;
+        }
+
+        @Specialization
+        public Object setTraceback(PBaseException self, PTraceback tb) {
+            self.setTraceback(tb);
+            return PNone.NONE;
+        }
+
+        @Fallback
+        public Object setTraceback(@SuppressWarnings("unused") Object self, @SuppressWarnings("unused") Object tb) {
+            throw raise(PythonErrorType.TypeError, "__traceback__ must be a traceback or None");
         }
     }
 
@@ -193,15 +213,15 @@ public Object traceback(PBaseException self) {
     public abstract static class WithTracebackNode extends PythonBuiltinNode {
 
         @Specialization
-        public Object withTraceback(PBaseException self, @SuppressWarnings("unused") PNone tb) {
+        public PBaseException withTraceback(PBaseException self, @SuppressWarnings("unused") PNone tb) {
             self.clearTraceback();
-            return PNone.NONE;
+            return self;
         }
 
         @Specialization
-        public Object withTraceback(PBaseException self, PTraceback tb) {
+        public PBaseException withTraceback(PBaseException self, PTraceback tb) {
             self.setTraceback(tb);
-            return PNone.NONE;
+            return self;
         }
     }
 }

mx.graalpython/copyrights/overrides

@@ -199,6 +199,7 @@ graalpython/com.oracle.graal.python.test/src/tests/test_compare.py,python.copyri
 graalpython/com.oracle.graal.python.test/src/tests/test_enumerate.py,python.copyright
 graalpython/com.oracle.graal.python.test/src/tests/test_euler11.py,benchmarks.copyright
 graalpython/com.oracle.graal.python.test/src/tests/test_euler31.py,benchmarks.copyright
+graalpython/com.oracle.graal.python.test/src/tests/test_exception.py,python.copyright
 graalpython/com.oracle.graal.python.test/src/tests/test_generator-accumulator.py,zippy.copyright
 graalpython/com.oracle.graal.python.test/src/tests/test_generator-continue.py,zippy.copyright
 graalpython/com.oracle.graal.python.test/src/tests/test_generator-expression-next.py,zippy.copyright