442 lines
15 KiB
Python
442 lines
15 KiB
Python
"""Python part of the warnings subsystem."""
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import sys
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__all__ = ["warn", "warn_explicit", "showwarning",
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"formatwarning", "filterwarnings", "simplefilter",
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"resetwarnings", "catch_warnings"]
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def showwarning(message, category, filename, lineno, file=None, line=None):
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"""Hook to write a warning to a file; replace if you like."""
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if file is None:
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file = sys.stderr
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if file is None:
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# sys.stderr is None when run with pythonw.exe - warnings get lost
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return
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try:
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file.write(formatwarning(message, category, filename, lineno, line))
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except OSError:
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pass # the file (probably stderr) is invalid - this warning gets lost.
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def formatwarning(message, category, filename, lineno, line=None):
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"""Function to format a warning the standard way."""
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s = "%s:%s: %s: %s\n" % (filename, lineno, category.__name__, message)
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if line is None:
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try:
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import linecache
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line = linecache.getline(filename, lineno)
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except Exception:
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# When a warning is logged during Python shutdown, linecache
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# and the import machinery don't work anymore
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line = None
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if line:
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line = line.strip()
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s += " %s\n" % line
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return s
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def filterwarnings(action, message="", category=Warning, module="", lineno=0,
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append=False):
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"""Insert an entry into the list of warnings filters (at the front).
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'action' -- one of "error", "ignore", "always", "default", "module",
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or "once"
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'message' -- a regex that the warning message must match
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'category' -- a class that the warning must be a subclass of
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'module' -- a regex that the module name must match
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'lineno' -- an integer line number, 0 matches all warnings
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'append' -- if true, append to the list of filters
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"""
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import re
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assert action in ("error", "ignore", "always", "default", "module",
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"once"), "invalid action: %r" % (action,)
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assert isinstance(message, str), "message must be a string"
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assert isinstance(category, type), "category must be a class"
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assert issubclass(category, Warning), "category must be a Warning subclass"
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assert isinstance(module, str), "module must be a string"
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assert isinstance(lineno, int) and lineno >= 0, \
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"lineno must be an int >= 0"
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item = (action, re.compile(message, re.I), category,
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re.compile(module), lineno)
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if append:
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filters.append(item)
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else:
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filters.insert(0, item)
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_filters_mutated()
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def simplefilter(action, category=Warning, lineno=0, append=False):
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"""Insert a simple entry into the list of warnings filters (at the front).
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A simple filter matches all modules and messages.
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'action' -- one of "error", "ignore", "always", "default", "module",
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or "once"
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'category' -- a class that the warning must be a subclass of
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'lineno' -- an integer line number, 0 matches all warnings
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'append' -- if true, append to the list of filters
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"""
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assert action in ("error", "ignore", "always", "default", "module",
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"once"), "invalid action: %r" % (action,)
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assert isinstance(lineno, int) and lineno >= 0, \
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"lineno must be an int >= 0"
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item = (action, None, category, None, lineno)
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if append:
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filters.append(item)
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else:
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filters.insert(0, item)
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_filters_mutated()
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def resetwarnings():
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"""Clear the list of warning filters, so that no filters are active."""
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filters[:] = []
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_filters_mutated()
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class _OptionError(Exception):
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"""Exception used by option processing helpers."""
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pass
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# Helper to process -W options passed via sys.warnoptions
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def _processoptions(args):
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for arg in args:
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try:
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_setoption(arg)
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except _OptionError as msg:
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print("Invalid -W option ignored:", msg, file=sys.stderr)
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# Helper for _processoptions()
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def _setoption(arg):
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import re
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parts = arg.split(':')
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if len(parts) > 5:
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raise _OptionError("too many fields (max 5): %r" % (arg,))
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while len(parts) < 5:
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parts.append('')
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action, message, category, module, lineno = [s.strip()
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for s in parts]
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action = _getaction(action)
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message = re.escape(message)
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category = _getcategory(category)
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module = re.escape(module)
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if module:
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module = module + '$'
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if lineno:
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try:
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lineno = int(lineno)
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if lineno < 0:
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raise ValueError
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except (ValueError, OverflowError):
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raise _OptionError("invalid lineno %r" % (lineno,))
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else:
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lineno = 0
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filterwarnings(action, message, category, module, lineno)
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# Helper for _setoption()
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def _getaction(action):
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if not action:
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return "default"
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if action == "all": return "always" # Alias
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for a in ('default', 'always', 'ignore', 'module', 'once', 'error'):
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if a.startswith(action):
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return a
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raise _OptionError("invalid action: %r" % (action,))
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# Helper for _setoption()
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def _getcategory(category):
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import re
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if not category:
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return Warning
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if re.match("^[a-zA-Z0-9_]+$", category):
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try:
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cat = eval(category)
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except NameError:
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raise _OptionError("unknown warning category: %r" % (category,))
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else:
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i = category.rfind(".")
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module = category[:i]
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klass = category[i+1:]
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try:
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m = __import__(module, None, None, [klass])
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except ImportError:
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raise _OptionError("invalid module name: %r" % (module,))
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try:
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cat = getattr(m, klass)
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except AttributeError:
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raise _OptionError("unknown warning category: %r" % (category,))
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if not issubclass(cat, Warning):
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raise _OptionError("invalid warning category: %r" % (category,))
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return cat
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def _is_internal_frame(frame):
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"""Signal whether the frame is an internal CPython implementation detail."""
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filename = frame.f_code.co_filename
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return 'importlib' in filename and '_bootstrap' in filename
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def _next_external_frame(frame):
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"""Find the next frame that doesn't involve CPython internals."""
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frame = frame.f_back
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while frame is not None and _is_internal_frame(frame):
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frame = frame.f_back
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return frame
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# Code typically replaced by _warnings
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def warn(message, category=None, stacklevel=1):
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"""Issue a warning, or maybe ignore it or raise an exception."""
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# Check if message is already a Warning object
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if isinstance(message, Warning):
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category = message.__class__
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# Check category argument
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if category is None:
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category = UserWarning
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if not (isinstance(category, type) and issubclass(category, Warning)):
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raise TypeError("category must be a Warning subclass, "
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"not '{:s}'".format(type(category).__name__))
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# Get context information
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try:
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if stacklevel <= 1 or _is_internal_frame(sys._getframe(1)):
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# If frame is too small to care or if the warning originated in
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# internal code, then do not try to hide any frames.
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frame = sys._getframe(stacklevel)
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else:
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frame = sys._getframe(1)
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# Look for one frame less since the above line starts us off.
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for x in range(stacklevel-1):
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frame = _next_external_frame(frame)
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if frame is None:
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raise ValueError
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except ValueError:
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globals = sys.__dict__
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lineno = 1
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else:
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globals = frame.f_globals
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lineno = frame.f_lineno
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if '__name__' in globals:
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module = globals['__name__']
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else:
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module = "<string>"
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filename = globals.get('__file__')
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if filename:
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fnl = filename.lower()
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if fnl.endswith(".pyc"):
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filename = filename[:-1]
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else:
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if module == "__main__":
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try:
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filename = sys.argv[0]
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except AttributeError:
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# embedded interpreters don't have sys.argv, see bug #839151
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filename = '__main__'
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if not filename:
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filename = module
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registry = globals.setdefault("__warningregistry__", {})
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warn_explicit(message, category, filename, lineno, module, registry,
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globals)
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def warn_explicit(message, category, filename, lineno,
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module=None, registry=None, module_globals=None):
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lineno = int(lineno)
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if module is None:
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module = filename or "<unknown>"
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if module[-3:].lower() == ".py":
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module = module[:-3] # XXX What about leading pathname?
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if registry is None:
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registry = {}
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if registry.get('version', 0) != _filters_version:
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registry.clear()
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registry['version'] = _filters_version
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if isinstance(message, Warning):
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text = str(message)
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category = message.__class__
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else:
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text = message
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message = category(message)
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key = (text, category, lineno)
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# Quick test for common case
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if registry.get(key):
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return
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# Search the filters
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for item in filters:
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action, msg, cat, mod, ln = item
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if ((msg is None or msg.match(text)) and
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issubclass(category, cat) and
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(mod is None or mod.match(module)) and
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(ln == 0 or lineno == ln)):
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break
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else:
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action = defaultaction
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# Early exit actions
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if action == "ignore":
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registry[key] = 1
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return
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# Prime the linecache for formatting, in case the
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# "file" is actually in a zipfile or something.
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import linecache
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linecache.getlines(filename, module_globals)
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if action == "error":
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raise message
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# Other actions
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if action == "once":
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registry[key] = 1
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oncekey = (text, category)
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if onceregistry.get(oncekey):
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return
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onceregistry[oncekey] = 1
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elif action == "always":
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pass
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elif action == "module":
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registry[key] = 1
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altkey = (text, category, 0)
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if registry.get(altkey):
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return
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registry[altkey] = 1
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elif action == "default":
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registry[key] = 1
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else:
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# Unrecognized actions are errors
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raise RuntimeError(
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"Unrecognized action (%r) in warnings.filters:\n %s" %
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(action, item))
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if not callable(showwarning):
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raise TypeError("warnings.showwarning() must be set to a "
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"function or method")
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# Print message and context
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showwarning(message, category, filename, lineno)
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class WarningMessage(object):
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"""Holds the result of a single showwarning() call."""
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_WARNING_DETAILS = ("message", "category", "filename", "lineno", "file",
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"line")
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def __init__(self, message, category, filename, lineno, file=None,
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line=None):
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local_values = locals()
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for attr in self._WARNING_DETAILS:
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setattr(self, attr, local_values[attr])
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self._category_name = category.__name__ if category else None
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def __str__(self):
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return ("{message : %r, category : %r, filename : %r, lineno : %s, "
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"line : %r}" % (self.message, self._category_name,
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self.filename, self.lineno, self.line))
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class catch_warnings(object):
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"""A context manager that copies and restores the warnings filter upon
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exiting the context.
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The 'record' argument specifies whether warnings should be captured by a
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custom implementation of warnings.showwarning() and be appended to a list
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returned by the context manager. Otherwise None is returned by the context
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manager. The objects appended to the list are arguments whose attributes
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mirror the arguments to showwarning().
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The 'module' argument is to specify an alternative module to the module
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named 'warnings' and imported under that name. This argument is only useful
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when testing the warnings module itself.
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"""
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def __init__(self, *, record=False, module=None):
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"""Specify whether to record warnings and if an alternative module
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should be used other than sys.modules['warnings'].
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For compatibility with Python 3.0, please consider all arguments to be
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keyword-only.
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"""
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self._record = record
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self._module = sys.modules['warnings'] if module is None else module
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self._entered = False
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def __repr__(self):
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args = []
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if self._record:
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args.append("record=True")
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if self._module is not sys.modules['warnings']:
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args.append("module=%r" % self._module)
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name = type(self).__name__
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return "%s(%s)" % (name, ", ".join(args))
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def __enter__(self):
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if self._entered:
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raise RuntimeError("Cannot enter %r twice" % self)
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self._entered = True
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self._filters = self._module.filters
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self._module.filters = self._filters[:]
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self._module._filters_mutated()
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self._showwarning = self._module.showwarning
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if self._record:
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log = []
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def showwarning(*args, **kwargs):
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log.append(WarningMessage(*args, **kwargs))
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self._module.showwarning = showwarning
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return log
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else:
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return None
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def __exit__(self, *exc_info):
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if not self._entered:
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raise RuntimeError("Cannot exit %r without entering first" % self)
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self._module.filters = self._filters
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self._module._filters_mutated()
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self._module.showwarning = self._showwarning
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# filters contains a sequence of filter 5-tuples
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# The components of the 5-tuple are:
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# - an action: error, ignore, always, default, module, or once
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# - a compiled regex that must match the warning message
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# - a class representing the warning category
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# - a compiled regex that must match the module that is being warned
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# - a line number for the line being warning, or 0 to mean any line
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# If either if the compiled regexs are None, match anything.
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_warnings_defaults = False
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try:
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from _warnings import (filters, _defaultaction, _onceregistry,
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warn, warn_explicit, _filters_mutated)
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defaultaction = _defaultaction
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onceregistry = _onceregistry
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_warnings_defaults = True
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except ImportError:
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filters = []
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defaultaction = "default"
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onceregistry = {}
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_filters_version = 1
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def _filters_mutated():
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global _filters_version
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_filters_version += 1
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# Module initialization
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_processoptions(sys.warnoptions)
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if not _warnings_defaults:
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silence = [ImportWarning, PendingDeprecationWarning]
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silence.append(DeprecationWarning)
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for cls in silence:
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simplefilter("ignore", category=cls)
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bytes_warning = sys.flags.bytes_warning
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if bytes_warning > 1:
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bytes_action = "error"
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elif bytes_warning:
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bytes_action = "default"
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else:
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bytes_action = "ignore"
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simplefilter(bytes_action, category=BytesWarning, append=1)
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# resource usage warnings are enabled by default in pydebug mode
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if hasattr(sys, 'gettotalrefcount'):
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resource_action = "always"
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else:
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resource_action = "ignore"
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simplefilter(resource_action, category=ResourceWarning, append=1)
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del _warnings_defaults
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