Python3-compatible fix: don't discard exception backtraces.

This is important; it's next to impossible to debug problems when backtraces are lost.

3 files changed, 14 insertions, 1 deletions

diff --git a/jsonschema.py b/jsonschema.py
index 7994bf0..20c7659 100644
--- a/jsonschema.py
+++ b/jsonschema.py
@@ -22,6 +22,11 @@ import warnings
 PY3 = sys.version_info[0] >= 3
 
 if PY3:
+    from raise_exception_3 import raise_exception_from
+else:
+    from raise_exception_2 import raise_exception_from
+
+if PY3:
     basestring = unicode = str
     iteritems = operator.methodcaller("items")
 else:
@@ -361,7 +366,7 @@ class Validator(object):
             try:
                 self._meta_validator.validate(schema, self._version)
             except ValidationError as e:
-                raise SchemaError(str(e))
+                raise_exception_from(SchemaError(str(e)), e)
 
         self._errors = []
         self._validate(instance, schema)
diff --git a/raise_exception_2.py b/raise_exception_2.py
new file mode 100644
index 0000000..d8489ca
--- /dev/null
+++ b/raise_exception_2.py
@@ -0,0 +1,5 @@
+# Raise an exception from another exception 2.x.
+import sys
+def raise_exception_from(exception, original_exception):
+    tb = sys.exc_info()[2]
+    raise exception, None, tb
diff --git a/raise_exception_3.py b/raise_exception_3.py
new file mode 100644
index 0000000..a74b1f6
--- /dev/null
+++ b/raise_exception_3.py
@@ -0,0 +1,3 @@
+# Raise an exception from another exception 3.x.
+def raise_exception_from(exception, original_exception):
+    raise exception from original_exception