Issue #18383: Avoid adding duplicate filters when warnings is reloaded
Based on patch by Alex Shkop.
diff --git a/Lib/warnings.py b/Lib/warnings.py
index dfa13ee..c6631fc 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -56,13 +56,8 @@
assert isinstance(module, str), "module must be a string"
assert isinstance(lineno, int) and lineno >= 0, \
"lineno must be an int >= 0"
- item = (action, re.compile(message, re.I), category,
- re.compile(module), lineno)
- if append:
- filters.append(item)
- else:
- filters.insert(0, item)
- _filters_mutated()
+ _add_filter(action, re.compile(message, re.I), category,
+ re.compile(module), lineno, append=append)
def simplefilter(action, category=Warning, lineno=0, append=False):
"""Insert a simple entry into the list of warnings filters (at the front).
@@ -78,11 +73,20 @@
"once"), "invalid action: %r" % (action,)
assert isinstance(lineno, int) and lineno >= 0, \
"lineno must be an int >= 0"
- item = (action, None, category, None, lineno)
- if append:
- filters.append(item)
- else:
+ _add_filter(action, None, category, None, lineno, append=append)
+
+def _add_filter(*item, append):
+ # Remove possible duplicate filters, so new one will be placed
+ # in correct place. If append=True and duplicate exists, do nothing.
+ if not append:
+ try:
+ filters.remove(item)
+ except ValueError:
+ pass
filters.insert(0, item)
+ else:
+ if item not in filters:
+ filters.append(item)
_filters_mutated()
def resetwarnings():