Source code for warnings
From Get docs
Python/docs/3.6/ modules/warnings
Source code for warnings
"""Python part of the warnings subsystem."""
import sys
__all__ = ["warn", "warn_explicit", "showwarning",
"formatwarning", "filterwarnings", "simplefilter",
"resetwarnings", "catch_warnings"]
[docs]def showwarning(message, category, filename, lineno, file=None, line=None):
"""Hook to write a warning to a file; replace if you like."""
msg = WarningMessage(message, category, filename, lineno, file, line)
_showwarnmsg_impl(msg)
[docs]def formatwarning(message, category, filename, lineno, line=None):
"""Function to format a warning the standard way."""
msg = WarningMessage(message, category, filename, lineno, None, line)
return _formatwarnmsg_impl(msg)
def _showwarnmsg_impl(msg):
file = msg.file
if file is None:
file = sys.stderr
if file is None:
# sys.stderr is None when run with pythonw.exe:
# warnings get lost
return
text = _formatwarnmsg(msg)
try:
file.write(text)
except OSError:
# the file (probably stderr) is invalid - this warning gets lost.
pass
def _formatwarnmsg_impl(msg):
category = msg.category.__name__
s = f"{msg.filename}:{msg.lineno}: {category}: {msg.message}\n"
if msg.line is None:
try:
import linecache
line = linecache.getline(msg.filename, msg.lineno)
except Exception:
# When a warning is logged during Python shutdown, linecache
# and the import machinery don't work anymore
line = None
linecache = None
else:
line = msg.line
if line:
line = line.strip()
s += " %s\n" % line
if msg.source is not None:
try:
import tracemalloc
# Logging a warning should not raise a new exception:
# catch Exception, not only ImportError and RecursionError.
except Exception:
# don't suggest to enable tracemalloc if it's not available
tracing = True
tb = None
else:
tracing = tracemalloc.is_tracing()
try:
tb = tracemalloc.get_object_traceback(msg.source)
except Exception:
# When a warning is logged during Python shutdown, tracemalloc
# and the import machinery don't work anymore
tb = None
if tb is not None:
s += 'Object allocated at (most recent call last):\n'
for frame in tb:
s += (' File "%s", lineno %s\n'
% (frame.filename, frame.lineno))
try:
if linecache is not None:
line = linecache.getline(frame.filename, frame.lineno)
else:
line = None
except Exception:
line = None
if line:
line = line.strip()
s += ' %s\n' % line
elif not tracing:
s += (f'{category}: Enable tracemalloc to get the object '
f'allocation traceback\n')
return s
# Keep a reference to check if the function was replaced
_showwarning_orig = showwarning
def _showwarnmsg(msg):
"""Hook to write a warning to a file; replace if you like."""
try:
sw = showwarning
except NameError:
pass
else:
if sw is not _showwarning_orig:
# warnings.showwarning() was replaced
if not callable(sw):
raise TypeError("warnings.showwarning() must be set to a "
"function or method")
sw(msg.message, msg.category, msg.filename, msg.lineno,
msg.file, msg.line)
return
_showwarnmsg_impl(msg)
# Keep a reference to check if the function was replaced
_formatwarning_orig = formatwarning
def _formatwarnmsg(msg):
"""Function to format a warning the standard way."""
try:
fw = formatwarning
except NameError:
pass
else:
if fw is not _formatwarning_orig:
# warnings.formatwarning() was replaced
return fw(msg.message, msg.category,
msg.filename, msg.lineno, msg.line)
return _formatwarnmsg_impl(msg)
[docs]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
"""
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"
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)
[docs]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()
[docs]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):
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)
category = _getcategory(category)
if message or module:
import re
if message:
message = re.escape(message)
if module:
module = re.escape(module) + r'\Z'
if lineno:
try:
lineno = int(lineno)
if lineno < 0:
raise ValueError
except (ValueError, OverflowError):
raise _OptionError("invalid lineno %r" % (lineno,)) from None
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):
if not category:
return Warning
if '.' not in category:
import builtins as m
klass = category
else:
module, _, klass = category.rpartition('.')
try:
m = __import__(module, None, None, [klass])
except ImportError:
raise _OptionError("invalid module name: %r" % (module,)) from None
try:
cat = getattr(m, klass)
except AttributeError:
raise _OptionError("unknown warning category: %r" % (category,)) from None
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, source=None):
"""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__
filename = "sys"
lineno = 1
else:
globals = frame.f_globals
filename = frame.f_code.co_filename
lineno = frame.f_lineno
if '__name__' in globals:
module = globals['__name__']
else:
module = "<string>"
registry = globals.setdefault("__warningregistry__", {})
warn_explicit(message, category, filename, lineno, module, registry,
globals, source)
def warn_explicit(message, category, filename, lineno,
module=None, registry=None, module_globals=None,
source=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":
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))
# Print message and context
msg = WarningMessage(message, category, filename, lineno, source)
_showwarnmsg(msg)
class WarningMessage(object):
_WARNING_DETAILS = ("message", "category", "filename", "lineno", "file",
"line", "source")
def __init__(self, message, category, filename, lineno, file=None,
line=None, source=None):
self.message = message
self.category = category
self.filename = filename
self.lineno = lineno
self.file = file
self.line = line
self.source = source
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))
[docs]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
self._showwarnmsg_impl = self._module._showwarnmsg_impl
if self._record:
log = []
self._module._showwarnmsg_impl = log.append
# Reset showwarning() to the default implementation to make sure
# that _showwarnmsg() calls _showwarnmsg_impl()
self._module.showwarning = self._module._showwarning_orig
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
self._module._showwarnmsg_impl = self._showwarnmsg_impl
# Private utility function called by _PyErr_WarnUnawaitedCoroutine
def _warn_unawaited_coroutine(coro):
msg_lines = [
f"coroutine '{coro.__qualname__}' was never awaited\n"
]
if coro.cr_origin is not None:
import linecache, traceback
def extract():
for filename, lineno, funcname in reversed(coro.cr_origin):
line = linecache.getline(filename, lineno)
yield (filename, lineno, funcname, line)
msg_lines.append("Coroutine created at (most recent call last)\n")
msg_lines += traceback.format_list(list(extract()))
msg = "".join(msg_lines).rstrip("\n")
# Passing source= here means that if the user happens to have tracemalloc
# enabled and tracking where the coroutine was created, the warning will
# contain that traceback. This does mean that if they have *both*
# coroutine origin tracking *and* tracemalloc enabled, they'll get two
# partially-redundant tracebacks. If we wanted to be clever we could
# probably detect this case and avoid it, but for now we don't bother.
warn(msg, category=RuntimeWarning, stacklevel=2, source=coro)
# 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.
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
_warnings_defaults = False
# Module initialization
_processoptions(sys.warnoptions)
if not _warnings_defaults:
# Several warning categories are ignored by default in regular builds
if not hasattr(sys, 'gettotalrefcount'):
filterwarnings("default", category=DeprecationWarning,
module="__main__", append=1)
simplefilter("ignore", category=DeprecationWarning, append=1)
simplefilter("ignore", category=PendingDeprecationWarning, append=1)
simplefilter("ignore", category=ImportWarning, append=1)
simplefilter("ignore", category=ResourceWarning, append=1)
del _warnings_defaults
