bpo-29762: More use "raise from None". (#569)

This hides unwanted implementation details from tracebacks.

1 files changed, 4 insertions, 4 deletions

diff --git a/Lib/warnings.py b/Lib/warnings.py
index 5badb0b..d7d88d3 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -209,7 +209,7 @@ def _setoption(arg):
             if lineno < 0:
                 raise ValueError
         except (ValueError, OverflowError):
-            raise _OptionError("invalid lineno %r" % (lineno,))
+            raise _OptionError("invalid lineno %r" % (lineno,)) from None
     else:
         lineno = 0
     filterwarnings(action, message, category, module, lineno)
@@ -233,7 +233,7 @@ def _getcategory(category):
         try:
             cat = eval(category)
         except NameError:
-            raise _OptionError("unknown warning category: %r" % (category,))
+            raise _OptionError("unknown warning category: %r" % (category,)) from None
     else:
         i = category.rfind(".")
         module = category[:i]
@@ -241,11 +241,11 @@ def _getcategory(category):
         try:
             m = __import__(module, None, None, [klass])
         except ImportError:
-            raise _OptionError("invalid module name: %r" % (module,))
+            raise _OptionError("invalid module name: %r" % (module,)) from None
         try:
             cat = getattr(m, klass)
         except AttributeError:
-            raise _OptionError("unknown warning category: %r" % (category,))
+            raise _OptionError("unknown warning category: %r" % (category,)) from None
     if not issubclass(cat, Warning):
         raise _OptionError("invalid warning category: %r" % (category,))
     return cat