bpo-27535: Optimize warnings.warn() (#4508)
* Optimize warnings.filterwarnings(). Replace re.compile('') with
None to avoid the cost of calling a regex.match() method, whereas
it always matchs.
* Optimize get_warnings_attr(): replace PyObject_GetAttrString() with
_PyObject_GetAttrId().
Cleanup also create_filter():
* Use _Py_IDENTIFIER() to allow to cleanup strings at Python
finalization
* Replace Py_FatalError() with a regular exceptions
diff --git a/Lib/warnings.py b/Lib/warnings.py
index b2605f8..5b62569 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -128,7 +128,6 @@
'lineno' -- an integer line number, 0 matches all warnings
'append' -- if true, append to the list of filters
"""
- import re
assert action in ("error", "ignore", "always", "default", "module",
"once"), "invalid action: %r" % (action,)
assert isinstance(message, str), "message must be a string"
@@ -137,8 +136,20 @@
assert isinstance(module, str), "module must be a string"
assert isinstance(lineno, int) and lineno >= 0, \
"lineno must be an int >= 0"
- _add_filter(action, re.compile(message, re.I), category,
- re.compile(module), lineno, append=append)
+
+ if message or module:
+ import re
+
+ if message:
+ message = re.compile(message, re.I)
+ else:
+ message = None
+ if module:
+ module = re.compile(module)
+ else:
+ module = None
+
+ _add_filter(action, message, category, 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).