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