Name	Size	Mode	Actions
2to3.rst.txt	15898	0644	editdlrm
abc.rst.txt	11805	0644	editdlrm
aifc.rst.txt	7503	0644	editdlrm
allos.rst.txt	678	0644	editdlrm
archiving.rst.txt	440	0644	editdlrm
argparse.rst.txt	77480	0644	editdlrm
array.rst.txt	10812	0644	editdlrm
ast.rst.txt	10159	0644	editdlrm
asynchat.rst.txt	8528	0644	editdlrm
asyncio-dev.rst.txt	13398	0644	editdlrm
asyncio-eventloop.rst.txt	33701	0644	editdlrm
asyncio-eventloops.rst.txt	7660	0644	editdlrm
asyncio-protocol.rst.txt	25170	0644	editdlrm
asyncio-queue.rst.txt	4328	0644	editdlrm
asyncio-stream.rst.txt	14363	0644	editdlrm
asyncio-subprocess.rst.txt	15544	0644	editdlrm
asyncio-sync.rst.txt	9078	0644	editdlrm
asyncio-task.rst.txt	25406	0644	editdlrm
asyncio.rst.txt	2272	0644	editdlrm
asyncore.rst.txt	13624	0644	editdlrm
atexit.rst.txt	3669	0644	editdlrm
audioop.rst.txt	10712	0644	editdlrm
base64.rst.txt	10371	0644	editdlrm
bdb.rst.txt	12985	0644	editdlrm
binary.rst.txt	654	0644	editdlrm
binascii.rst.txt	6539	0644	editdlrm
binhex.rst.txt	1709	0644	editdlrm
bisect.rst.txt	5398	0644	editdlrm
builtins.rst.txt	1465	0644	editdlrm
bz2.rst.txt	8825	0644	editdlrm
calendar.rst.txt	10988	0644	editdlrm
cgi.rst.txt	22650	0644	editdlrm
cgitb.rst.txt	2918	0644	editdlrm
chunk.rst.txt	5094	0644	editdlrm
cmath.rst.txt	9326	0644	editdlrm
cmd.rst.txt	13795	0644	editdlrm
code.rst.txt	7817	0644	editdlrm
codecs.rst.txt	75564	0644	editdlrm
codeop.rst.txt	3021	0644	editdlrm
collections.abc.rst.txt	12861	0644	editdlrm
collections.rst.txt	46063	0644	editdlrm
colorsys.rst.txt	1820	0644	editdlrm
compileall.rst.txt	8975	0644	editdlrm
concurrency.rst.txt	673	0644	editdlrm
concurrent.futures.rst.txt	16910	0644	editdlrm
concurrent.rst.txt	171	0644	editdlrm
configparser.rst.txt	48756	0644	editdlrm
constants.rst.txt	3331	0644	editdlrm
contextlib.rst.txt	28175	0644	editdlrm
copy.rst.txt	3378	0644	editdlrm
copyreg.rst.txt	2182	0644	editdlrm
crypt.rst.txt	5122	0644	editdlrm
crypto.rst.txt	411	0644	editdlrm
csv.rst.txt	19902	0644	editdlrm
ctypes.rst.txt	88613	0644	editdlrm
curses.ascii.rst.txt	8920	0644	editdlrm
curses.panel.rst.txt	2764	0644	editdlrm
curses.rst.txt	76397	0644	editdlrm
custominterp.rst.txt	569	0644	editdlrm
datatypes.rst.txt	751	0644	editdlrm
datetime.rst.txt	90524	0644	editdlrm
dbm.rst.txt	14293	0644	editdlrm
debug.rst.txt	471	0644	editdlrm
decimal.rst.txt	74869	0644	editdlrm
development.rst.txt	704	0644	editdlrm
difflib.rst.txt	29861	0644	editdlrm
dis.rst.txt	32567	0644	editdlrm
distribution.rst.txt	452	0644	editdlrm
distutils.rst.txt	1974	0644	editdlrm
doctest.rst.txt	71743	0644	editdlrm
dummy_threading.rst.txt	784	0644	editdlrm
email.charset.rst.txt	9293	0644	editdlrm
email.compat32-message.rst.txt	33493	0644	editdlrm
email.contentmanager.rst.txt	9112	0644	editdlrm
email.encoders.rst.txt	2715	0644	editdlrm
email.errors.rst.txt	4792	0644	editdlrm
email.examples.rst.txt	1915	0644	editdlrm
email.generator.rst.txt	13637	0644	editdlrm
email.header.rst.txt	9188	0644	editdlrm
email.headerregistry.rst.txt	17957	0644	editdlrm
email.iterators.rst.txt	2795	0644	editdlrm
email.message.rst.txt	33008	0644	editdlrm
email.mime.rst.txt	11721	0644	editdlrm
email.parser.rst.txt	14092	0644	editdlrm
email.policy.rst.txt	27022	0644	editdlrm
email.rst.txt	6785	0644	editdlrm
email.util.rst.txt	9214	0644	editdlrm
ensurepip.rst.txt	4987	0644	editdlrm
enum.rst.txt	32751	0644	editdlrm
errno.rst.txt	6811	0644	editdlrm
exceptions.rst.txt	25570	0644	editdlrm
faulthandler.rst.txt	6136	0644	editdlrm
fcntl.rst.txt	7152	0644	editdlrm
filecmp.rst.txt	5623	0644	editdlrm
fileformats.rst.txt	287	0644	editdlrm
fileinput.rst.txt	8051	0644	editdlrm
filesys.rst.txt	961	0644	editdlrm
fnmatch.rst.txt	3103	0644	editdlrm
formatter.rst.txt	13242	0644	editdlrm
fpectl.rst.txt	4180	0644	editdlrm
fractions.rst.txt	6364	0644	editdlrm
frameworks.rst.txt	391	0644	editdlrm
ftplib.rst.txt	17552	0644	editdlrm
functional.rst.txt	365	0644	editdlrm
functions.rst.txt	71621	0644	editdlrm
functools.rst.txt	18503	0644	editdlrm
gc.rst.txt	9694	0644	editdlrm
getopt.rst.txt	6557	0644	editdlrm
getpass.rst.txt	1882	0644	editdlrm
gettext.rst.txt	25588	0644	editdlrm
glob.rst.txt	3508	0644	editdlrm
grp.rst.txt	2417	0644	editdlrm
gzip.rst.txt	8301	0644	editdlrm
hashlib.rst.txt	26523	0644	editdlrm
heapq.rst.txt	13402	0644	editdlrm
hmac.rst.txt	4020	0644	editdlrm
html.entities.rst.txt	1319	0644	editdlrm
html.parser.rst.txt	11275	0644	editdlrm
html.rst.txt	1304	0644	editdlrm
http.client.rst.txt	18870	0644	editdlrm
http.cookiejar.rst.txt	27832	0644	editdlrm
http.cookies.rst.txt	8645	0644	editdlrm
http.rst.txt	7096	0644	editdlrm
http.server.rst.txt	17639	0644	editdlrm
i18n.rst.txt	408	0644	editdlrm
idle.rst.txt	25834	0644	editdlrm
imaplib.rst.txt	20367	0644	editdlrm
imghdr.rst.txt	2938	0644	editdlrm
imp.rst.txt	15548	0644	editdlrm
importlib.rst.txt	53563	0644	editdlrm
index.rst.txt	2258	0644	editdlrm
inspect.rst.txt	53928	0644	editdlrm
internet.rst.txt	992	0644	editdlrm
intro.rst.txt	2645	0644	editdlrm
io.rst.txt	40328	0644	editdlrm
ipaddress.rst.txt	32340	0644	editdlrm
ipc.rst.txt	649	0644	editdlrm
itertools.rst.txt	38459	0644	editdlrm
json.rst.txt	27876	0644	editdlrm
keyword.rst.txt	617	0644	editdlrm
language.rst.txt	522	0644	editdlrm
linecache.rst.txt	2408	0644	editdlrm
locale.rst.txt	25470	0644	editdlrm
logging.config.rst.txt	33886	0644	editdlrm
logging.handlers.rst.txt	42497	0644	editdlrm
logging.rst.txt	60479	0644	editdlrm
lzma.rst.txt	17361	0644	editdlrm
macpath.rst.txt	707	0644	editdlrm
mailbox.rst.txt	63055	0644	editdlrm
mailcap.rst.txt	3691	0644	editdlrm
markup.rst.txt	679	0644	editdlrm
marshal.rst.txt	4855	0644	editdlrm
math.rst.txt	14375	0644	editdlrm
mimetypes.rst.txt	9839	0644	editdlrm
misc.rst.txt	247	0644	editdlrm
mm.rst.txt	431	0644	editdlrm
mmap.rst.txt	11232	0644	editdlrm
modulefinder.rst.txt	3240	0644	editdlrm
modules.rst.txt	355	0644	editdlrm
msilib.rst.txt	18612	0644	editdlrm
msvcrt.rst.txt	4392	0644	editdlrm
multiprocessing.rst.txt	104494	0644	editdlrm
netdata.rst.txt	339	0644	editdlrm
netrc.rst.txt	3007	0644	editdlrm
nis.rst.txt	1993	0644	editdlrm
nntplib.rst.txt	21821	0644	editdlrm
numbers.rst.txt	8089	0644	editdlrm
numeric.rst.txt	696	0644	editdlrm
operator.rst.txt	18989	0644	editdlrm
optparse.rst.txt	76996	0644	editdlrm
os.path.rst.txt	16419	0644	editdlrm
os.rst.txt	137534	0644	editdlrm
ossaudiodev.rst.txt	17845	0644	editdlrm
othergui.rst.txt	2822	0644	editdlrm
parser.rst.txt	15148	0644	editdlrm
pathlib.rst.txt	30045	0644	editdlrm
pdb.rst.txt	19454	0644	editdlrm
persistence.rst.txt	591	0644	editdlrm
pickle.rst.txt	37440	0644	editdlrm
pickletools.rst.txt	3729	0644	editdlrm
pipes.rst.txt	2557	0644	editdlrm
pkgutil.rst.txt	8730	0644	editdlrm
platform.rst.txt	9624	0644	editdlrm
plistlib.rst.txt	7398	0644	editdlrm
poplib.rst.txt	8197	0644	editdlrm
posix.rst.txt	3694	0644	editdlrm
pprint.rst.txt	14274	0644	editdlrm
profile.rst.txt	27969	0644	editdlrm
pty.rst.txt	3123	0644	editdlrm
pwd.rst.txt	2739	0644	editdlrm
pyclbr.rst.txt	3297	0644	editdlrm
pydoc.rst.txt	4688	0644	editdlrm
pyexpat.rst.txt	28620	0644	editdlrm
python.rst.txt	475	0644	editdlrm
py_compile.rst.txt	3851	0644	editdlrm
queue.rst.txt	7268	0644	editdlrm
quopri.rst.txt	2571	0644	editdlrm
random.rst.txt	18503	0644	editdlrm
re.rst.txt	64936	0644	editdlrm
readline.rst.txt	11943	0644	editdlrm
reprlib.rst.txt	5162	0644	editdlrm
resource.rst.txt	12291	0644	editdlrm
rlcompleter.rst.txt	2294	0644	editdlrm
runpy.rst.txt	8285	0644	editdlrm
sched.rst.txt	4842	0644	editdlrm
secrets.rst.txt	5930	0644	editdlrm
select.rst.txt	28175	0644	editdlrm
selectors.rst.txt	8925	0644	editdlrm
shelve.rst.txt	8390	0644	editdlrm
shlex.rst.txt	16441	0644	editdlrm
shutil.rst.txt	26014	0644	editdlrm
signal.rst.txt	17218	0644	editdlrm
site.rst.txt	9628	0644	editdlrm
smtpd.rst.txt	10806	0644	editdlrm
smtplib.rst.txt	23439	0644	editdlrm
sndhdr.rst.txt	1994	0644	editdlrm
socket.rst.txt	68202	0644	editdlrm
socketserver.rst.txt	23712	0644	editdlrm
spwd.rst.txt	2958	0644	editdlrm
sqlite3.rst.txt	39215	0644	editdlrm
ssl.rst.txt	96021	0644	editdlrm
stat.rst.txt	9805	0644	editdlrm
statistics.rst.txt	15301	0644	editdlrm
stdtypes.rst.txt	179240	0644	editdlrm
string.rst.txt	35374	0644	editdlrm
stringprep.rst.txt	4279	0644	editdlrm
struct.rst.txt	19581	0644	editdlrm
subprocess.rst.txt	45793	0644	editdlrm
sunau.rst.txt	7390	0644	editdlrm
superseded.rst.txt	258	0644	editdlrm
symbol.rst.txt	975	0644	editdlrm
symtable.rst.txt	4964	0644	editdlrm
sys.rst.txt	58273	0644	editdlrm
sysconfig.rst.txt	8749	0644	editdlrm
syslog.rst.txt	4302	0644	editdlrm
tabnanny.rst.txt	2007	0644	editdlrm
tarfile.rst.txt	31749	0644	editdlrm
telnetlib.rst.txt	7899	0644	editdlrm
tempfile.rst.txt	13857	0644	editdlrm
termios.rst.txt	3751	0644	editdlrm
test.rst.txt	25764	0644	editdlrm
text.rst.txt	584	0644	editdlrm
textwrap.rst.txt	10519	0644	editdlrm
threading.rst.txt	39257	0644	editdlrm
time.rst.txt	32967	0644	editdlrm
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tk.rst.txt	1639	0644	editdlrm
tkinter.rst.txt	33027	0644	editdlrm
tkinter.scrolledtext.rst.txt	1255	0644	editdlrm
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tkinter.ttk.rst.txt	58489	0644	editdlrm
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tracemalloc.rst.txt	22089	0644	editdlrm
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unittest.rst.txt	93304	0644	editdlrm
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xml.dom.rst.txt	39507	0644	editdlrm
xml.etree.elementtree.rst.txt	43871	0644	editdlrm
xml.rst.txt	6071	0644	editdlrm
xml.sax.handler.rst.txt	15399	0644	editdlrm
xml.sax.reader.rst.txt	12133	0644	editdlrm
xml.sax.rst.txt	7159	0644	editdlrm
xml.sax.utils.rst.txt	3901	0644	editdlrm
xmlrpc.client.rst.txt	23071	0644	editdlrm
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zipapp.rst.txt	17392	0644	editdlrm
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zipimport.rst.txt	5805	0644	editdlrm
zlib.rst.txt	13912	0644	editdlrm
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__future__.rst.txt	5245	0644	editdlrm
__main__.rst.txt	904	0644	editdlrm

:mod:`warnings` --- Warning control =================================== .. module:: warnings :synopsis: Issue warning messages and control their disposition. **Source code:** :source:`Lib/warnings.py` .. index:: single: warnings -------------- Warning messages are typically issued in situations where it is useful to alert the user of some condition in a program, where that condition (normally) doesn't warrant raising an exception and terminating the program. For example, one might want to issue a warning when a program uses an obsolete module. Python programmers issue warnings by calling the :func:`warn` function defined in this module. (C programmers use :c:func:`PyErr_WarnEx`; see :ref:`exceptionhandling` for details). Warning messages are normally written to ``sys.stderr``, but their disposition can be changed flexibly, from ignoring all warnings to turning them into exceptions. The disposition of warnings can vary based on the warning category (see below), the text of the warning message, and the source location where it is issued. Repetitions of a particular warning for the same source location are typically suppressed. There are two stages in warning control: first, each time a warning is issued, a determination is made whether a message should be issued or not; next, if a message is to be issued, it is formatted and printed using a user-settable hook. The determination whether to issue a warning message is controlled by the warning filter, which is a sequence of matching rules and actions. Rules can be added to the filter by calling :func:`filterwarnings` and reset to its default state by calling :func:`resetwarnings`. The printing of warning messages is done by calling :func:`showwarning`, which may be overridden; the default implementation of this function formats the message by calling :func:`formatwarning`, which is also available for use by custom implementations. .. seealso:: :func:`logging.captureWarnings` allows you to handle all warnings with the standard logging infrastructure. .. _warning-categories: Warning Categories ------------------ There are a number of built-in exceptions that represent warning categories. This categorization is useful to be able to filter out groups of warnings. The following warnings category classes are currently defined: .. tabularcolumns:: |l|p{0.6\linewidth}| +----------------------------------+-----------------------------------------------+ | Class | Description | +==================================+===============================================+ | :exc:`Warning` | This is the base class of all warning | | | category classes. It is a subclass of | | | :exc:`Exception`. | +----------------------------------+-----------------------------------------------+ | :exc:`UserWarning` | The default category for :func:`warn`. | +----------------------------------+-----------------------------------------------+ | :exc:`DeprecationWarning` | Base category for warnings about deprecated | | | features (ignored by default). | +----------------------------------+-----------------------------------------------+ | :exc:`SyntaxWarning` | Base category for warnings about dubious | | | syntactic features. | +----------------------------------+-----------------------------------------------+ | :exc:`RuntimeWarning` | Base category for warnings about dubious | | | runtime features. | +----------------------------------+-----------------------------------------------+ | :exc:`FutureWarning` | Base category for warnings about constructs | | | that will change semantically in the future. | +----------------------------------+-----------------------------------------------+ | :exc:`PendingDeprecationWarning` | Base category for warnings about features | | | that will be deprecated in the future | | | (ignored by default). | +----------------------------------+-----------------------------------------------+ | :exc:`ImportWarning` | Base category for warnings triggered during | | | the process of importing a module (ignored by | | | default). | +----------------------------------+-----------------------------------------------+ | :exc:`UnicodeWarning` | Base category for warnings related to | | | Unicode. | +----------------------------------+-----------------------------------------------+ | :exc:`BytesWarning` | Base category for warnings related to | | | :class:`bytes` and :class:`bytearray`. | +----------------------------------+-----------------------------------------------+ | :exc:`ResourceWarning` | Base category for warnings related to | | | resource usage. | +----------------------------------+-----------------------------------------------+ While these are technically built-in exceptions, they are documented here, because conceptually they belong to the warnings mechanism. User code can define additional warning categories by subclassing one of the standard warning categories. A warning category must always be a subclass of the :exc:`Warning` class. .. _warning-filter: The Warnings Filter ------------------- The warnings filter controls whether warnings are ignored, displayed, or turned into errors (raising an exception). Conceptually, the warnings filter maintains an ordered list of filter specifications; any specific warning is matched against each filter specification in the list in turn until a match is found; the match determines the disposition of the match. Each entry is a tuple of the form (*action*, *message*, *category*, *module*, *lineno*), where: * *action* is one of the following strings: +---------------+----------------------------------------------+ | Value | Disposition | +===============+==============================================+ | ``"error"`` | turn matching warnings into exceptions | +---------------+----------------------------------------------+ | ``"ignore"`` | never print matching warnings | +---------------+----------------------------------------------+ | ``"always"`` | always print matching warnings | +---------------+----------------------------------------------+ | ``"default"`` | print the first occurrence of matching | | | warnings for each location where the warning | | | is issued | +---------------+----------------------------------------------+ | ``"module"`` | print the first occurrence of matching | | | warnings for each module where the warning | | | is issued | +---------------+----------------------------------------------+ | ``"once"`` | print only the first occurrence of matching | | | warnings, regardless of location | +---------------+----------------------------------------------+ * *message* is a string containing a regular expression that the start of the warning message must match. The expression is compiled to always be case-insensitive. * *category* is a class (a subclass of :exc:`Warning`) of which the warning category must be a subclass in order to match. * *module* is a string containing a regular expression that the module name must match. The expression is compiled to be case-sensitive. * *lineno* is an integer that the line number where the warning occurred must match, or ``0`` to match all line numbers. Since the :exc:`Warning` class is derived from the built-in :exc:`Exception` class, to turn a warning into an error we simply raise ``category(message)``. The warnings filter is initialized by :option:`-W` options passed to the Python interpreter command line. The interpreter saves the arguments for all :option:`-W` options without interpretation in ``sys.warnoptions``; the :mod:`warnings` module parses these when it is first imported (invalid options are ignored, after printing a message to ``sys.stderr``). Default Warning Filters ~~~~~~~~~~~~~~~~~~~~~~~ By default, Python installs several warning filters, which can be overridden by the command-line options passed to :option:`-W` and calls to :func:`filterwarnings`. * :exc:`DeprecationWarning` and :exc:`PendingDeprecationWarning`, and :exc:`ImportWarning` are ignored. * :exc:`BytesWarning` is ignored unless the :option:`-b` option is given once or twice; in this case this warning is either printed (``-b``) or turned into an exception (``-bb``). * :exc:`ResourceWarning` is ignored unless Python was built in debug mode. .. versionchanged:: 3.2 :exc:`DeprecationWarning` is now ignored by default in addition to :exc:`PendingDeprecationWarning`. .. _warning-suppress: Temporarily Suppressing Warnings -------------------------------- If you are using code that you know will raise a warning, such as a deprecated function, but do not want to see the warning, then it is possible to suppress the warning using the :class:`catch_warnings` context manager:: import warnings def fxn(): warnings.warn("deprecated", DeprecationWarning) with warnings.catch_warnings(): warnings.simplefilter("ignore") fxn() While within the context manager all warnings will simply be ignored. This allows you to use known-deprecated code without having to see the warning while not suppressing the warning for other code that might not be aware of its use of deprecated code. Note: this can only be guaranteed in a single-threaded application. If two or more threads use the :class:`catch_warnings` context manager at the same time, the behavior is undefined. .. _warning-testing: Testing Warnings ---------------- To test warnings raised by code, use the :class:`catch_warnings` context manager. With it you can temporarily mutate the warnings filter to facilitate your testing. For instance, do the following to capture all raised warnings to check:: import warnings def fxn(): warnings.warn("deprecated", DeprecationWarning) with warnings.catch_warnings(record=True) as w: # Cause all warnings to always be triggered. warnings.simplefilter("always") # Trigger a warning. fxn() # Verify some things assert len(w) == 1 assert issubclass(w[-1].category, DeprecationWarning) assert "deprecated" in str(w[-1].message) One can also cause all warnings to be exceptions by using ``error`` instead of ``always``. One thing to be aware of is that if a warning has already been raised because of a ``once``/``default`` rule, then no matter what filters are set the warning will not be seen again unless the warnings registry related to the warning has been cleared. Once the context manager exits, the warnings filter is restored to its state when the context was entered. This prevents tests from changing the warnings filter in unexpected ways between tests and leading to indeterminate test results. The :func:`showwarning` function in the module is also restored to its original value. Note: this can only be guaranteed in a single-threaded application. If two or more threads use the :class:`catch_warnings` context manager at the same time, the behavior is undefined. When testing multiple operations that raise the same kind of warning, it is important to test them in a manner that confirms each operation is raising a new warning (e.g. set warnings to be raised as exceptions and check the operations raise exceptions, check that the length of the warning list continues to increase after each operation, or else delete the previous entries from the warnings list before each new operation). .. _warning-ignored: Updating Code For New Versions of Python ---------------------------------------- Warnings that are only of interest to the developer are ignored by default. As such you should make sure to test your code with typically ignored warnings made visible. You can do this from the command-line by passing :option:`-Wd <-W>` to the interpreter (this is shorthand for :option:`!-W default`). This enables default handling for all warnings, including those that are ignored by default. To change what action is taken for encountered warnings you simply change what argument is passed to :option:`-W`, e.g. :option:`!-W error`. See the :option:`-W` flag for more details on what is possible. To programmatically do the same as :option:`!-Wd`, use:: warnings.simplefilter('default') Make sure to execute this code as soon as possible. This prevents the registering of what warnings have been raised from unexpectedly influencing how future warnings are treated. Having certain warnings ignored by default is done to prevent a user from seeing warnings that are only of interest to the developer. As you do not necessarily have control over what interpreter a user uses to run their code, it is possible that a new version of Python will be released between your release cycles. The new interpreter release could trigger new warnings in your code that were not there in an older interpreter, e.g. :exc:`DeprecationWarning` for a module that you are using. While you as a developer want to be notified that your code is using a deprecated module, to a user this information is essentially noise and provides no benefit to them. The :mod:`unittest` module has been also updated to use the ``'default'`` filter while running tests. .. _warning-functions: Available Functions ------------------- .. function:: warn(message, category=None, stacklevel=1, source=None) Issue a warning, or maybe ignore it or raise an exception. The *category* argument, if given, must be a warning category class (see above); it defaults to :exc:`UserWarning`. Alternatively *message* can be a :exc:`Warning` instance, in which case *category* will be ignored and ``message.__class__`` will be used. In this case the message text will be ``str(message)``. This function raises an exception if the particular warning issued is changed into an error by the warnings filter see above. The *stacklevel* argument can be used by wrapper functions written in Python, like this:: def deprecation(message): warnings.warn(message, DeprecationWarning, stacklevel=2) This makes the warning refer to :func:`deprecation`'s caller, rather than to the source of :func:`deprecation` itself (since the latter would defeat the purpose of the warning message). *source*, if supplied, is the destroyed object which emitted a :exc:`ResourceWarning`. .. versionchanged:: 3.6 Added *source* parameter. .. function:: warn_explicit(message, category, filename, lineno, module=None, registry=None, module_globals=None, source=None) This is a low-level interface to the functionality of :func:`warn`, passing in explicitly the message, category, filename and line number, and optionally the module name and the registry (which should be the ``__warningregistry__`` dictionary of the module). The module name defaults to the filename with ``.py`` stripped; if no registry is passed, the warning is never suppressed. *message* must be a string and *category* a subclass of :exc:`Warning` or *message* may be a :exc:`Warning` instance, in which case *category* will be ignored. *module_globals*, if supplied, should be the global namespace in use by the code for which the warning is issued. (This argument is used to support displaying source for modules found in zipfiles or other non-filesystem import sources). *source*, if supplied, is the destroyed object which emitted a :exc:`ResourceWarning`. .. versionchanged:: 3.6 Add the *source* parameter. .. function:: showwarning(message, category, filename, lineno, file=None, line=None) Write a warning to a file. The default implementation calls ``formatwarning(message, category, filename, lineno, line)`` and writes the resulting string to *file*, which defaults to ``sys.stderr``. You may replace this function with any callable by assigning to ``warnings.showwarning``. *line* is a line of source code to be included in the warning message; if *line* is not supplied, :func:`showwarning` will try to read the line specified by *filename* and *lineno*. .. function:: formatwarning(message, category, filename, lineno, line=None) Format a warning the standard way. This returns a string which may contain embedded newlines and ends in a newline. *line* is a line of source code to be included in the warning message; if *line* is not supplied, :func:`formatwarning` will try to read the line specified by *filename* and *lineno*. .. function:: filterwarnings(action, message='', category=Warning, module='', lineno=0, append=False) Insert an entry into the list of :ref:`warnings filter specifications `. The entry is inserted at the front by default; if *append* is true, it is inserted at the end. This checks the types of the arguments, compiles the *message* and *module* regular expressions, and inserts them as a tuple in the list of warnings filters. Entries closer to the front of the list override entries later in the list, if both match a particular warning. Omitted arguments default to a value that matches everything. .. function:: simplefilter(action, category=Warning, lineno=0, append=False) Insert a simple entry into the list of :ref:`warnings filter specifications `. The meaning of the function parameters is as for :func:`filterwarnings`, but regular expressions are not needed as the filter inserted always matches any message in any module as long as the category and line number match. .. function:: resetwarnings() Reset the warnings filter. This discards the effect of all previous calls to :func:`filterwarnings`, including that of the :option:`-W` command line options and calls to :func:`simplefilter`. Available Context Managers -------------------------- .. class:: catch_warnings(\*, record=False, module=None) A context manager that copies and, upon exit, restores the warnings filter and the :func:`showwarning` function. If the *record* argument is :const:`False` (the default) the context manager returns :class:`None` on entry. If *record* is :const:`True`, a list is returned that is progressively populated with objects as seen by a custom :func:`showwarning` function (which also suppresses output to ``sys.stdout``). Each object in the list has attributes with the same names as the arguments to :func:`showwarning`. The *module* argument takes a module that will be used instead of the module returned when you import :mod:`warnings` whose filter will be protected. This argument exists primarily for testing the :mod:`warnings` module itself. .. note:: The :class:`catch_warnings` manager works by replacing and then later restoring the module's :func:`showwarning` function and internal list of filter specifications. This means the context manager is modifying global state and therefore is not thread-safe.