DeprecationWarning is now silent by default.
This was originally suggested by Guido, discussed on the stdlib-sig mailing
list, and given the OK by Guido directly to me. What this change essentially
means is that Python has taken a policy of silencing warnings that are only
of interest to developers by default. This should prevent users from seeing
warnings which are triggered by an application being run against a new
interpreter before the app developer has a chance to update their code.
Closes issue #7319. Thanks to Antoine Pitrou, Ezio Melotti, and Brian Curtin
for helping with the issue.
diff --git a/Doc/library/warnings.rst b/Doc/library/warnings.rst
index b018a33..e4343e8 100644
--- a/Doc/library/warnings.rst
+++ b/Doc/library/warnings.rst
@@ -59,7 +59,7 @@
| :exc:`UserWarning` | The default category for :func:`warn`. |
+----------------------------------+-----------------------------------------------+
| :exc:`DeprecationWarning` | Base category for warnings about deprecated |
-| | features. |
+| | features (ignored by default). |
+----------------------------------+-----------------------------------------------+
| :exc:`SyntaxWarning` | Base category for warnings about dubious |
| | syntactic features. |
@@ -89,6 +89,9 @@
standard warning categories. A warning category must always be a subclass of
the :exc:`Warning` class.
+.. versionchanged:: 2.7
+ :exc:`DeprecationWarning` is ignored by default.
+
.. _warning-filter:
@@ -148,14 +151,6 @@
:mod:`warnings` module parses these when it is first imported (invalid options
are ignored, after printing a message to ``sys.stderr``).
-The warnings that are ignored by default may be enabled by passing :option:`-Wd`
-to the interpreter. This enables default handling for all warnings, including
-those that are normally ignored by default. This is particular useful for
-enabling ImportWarning when debugging problems importing a developed package.
-ImportWarning can also be enabled explicitly in Python code using::
-
- warnings.simplefilter('default', ImportWarning)
-
.. _warning-suppress:
@@ -226,6 +221,37 @@
entries from the warnings list before each new operation).
+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`
+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.
+
+
.. _warning-functions:
Available Functions
diff --git a/Lib/test/test_ascii_formatd.py b/Lib/test/test_ascii_formatd.py
index 5ee84fa..77759fe 100644
--- a/Lib/test/test_ascii_formatd.py
+++ b/Lib/test/test_ascii_formatd.py
@@ -4,6 +4,7 @@
import unittest
from test_support import check_warnings, run_unittest, cpython_only
+import warnings
class FormatDeprecationTests(unittest.TestCase):
@@ -17,6 +18,7 @@
buf = create_string_buffer(' ' * 100)
with check_warnings() as w:
+ warnings.simplefilter('default')
PyOS_ascii_formatd(byref(buf), sizeof(buf), '%+.10f',
c_double(10.0))
self.assertEqual(buf.value, '+10.0000000000')
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index a30f42b..3a2bdf5 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -309,6 +309,7 @@
# BaseException.__init__ triggers a deprecation warning.
exc = BaseException("foo")
with warnings.catch_warnings(record=True) as w:
+ warnings.simplefilter('default')
self.assertEquals(exc.message, "foo")
self.assertEquals(len(w), 1)
self.assertEquals(w[0].category, DeprecationWarning)
diff --git a/Lib/warnings.py b/Lib/warnings.py
index 8d46cd6..a88e7ba 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -383,8 +383,8 @@
# Module initialization
_processoptions(sys.warnoptions)
if not _warnings_defaults:
- simplefilter("ignore", category=PendingDeprecationWarning, append=1)
- simplefilter("ignore", category=ImportWarning, append=1)
+ for cls in (DeprecationWarning, PendingDeprecationWarning, ImportWarning):
+ simplefilter("ignore", category=cls, append=True)
bytes_warning = sys.flags.bytes_warning
if bytes_warning > 1:
bytes_action = "error"
diff --git a/Misc/NEWS b/Misc/NEWS
index c0f23b5..979ac8b 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@
Core and Builtins
-----------------
+- Issue #7319: Silence DeprecationWarning by default.
+
- Issue #2335: Backport set literals syntax from Python 3.x.
Library
diff --git a/Python/_warnings.c b/Python/_warnings.c
index 18fcdac..96bb049 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -85,10 +85,10 @@
default_action = get_warnings_attr("defaultaction");
if (default_action == NULL) {
- if (PyErr_Occurred()) {
- return NULL;
- }
- return _default_action;
+ if (PyErr_Occurred()) {
+ return NULL;
+ }
+ return _default_action;
}
Py_DECREF(_default_action);
@@ -202,12 +202,12 @@
mod_str = PyString_AsString(filename);
if (mod_str == NULL)
- return NULL;
+ return NULL;
len = PyString_Size(filename);
if (len < 0)
return NULL;
if (len >= 3 &&
- strncmp(mod_str + (len - 3), ".py", 3) == 0) {
+ strncmp(mod_str + (len - 3), ".py", 3) == 0) {
module = PyString_FromStringAndSize(mod_str, len-3);
}
else {
@@ -251,7 +251,7 @@
name = PyObject_GetAttrString(category, "__name__");
if (name == NULL) /* XXX Can an object lack a '__name__' attribute? */
- return;
+ return;
f_stderr = PySys_GetObject("stderr");
if (f_stderr == NULL) {
@@ -341,7 +341,7 @@
rc = already_warned(registry, key, 0);
if (rc == -1)
goto cleanup;
- else if (rc == 1)
+ else if (rc == 1)
goto return_none;
/* Else this warning hasn't been generated before. */
}
@@ -492,9 +492,9 @@
/* Setup filename. */
*filename = PyDict_GetItemString(globals, "__file__");
if (*filename != NULL) {
- Py_ssize_t len = PyString_Size(*filename);
+ Py_ssize_t len = PyString_Size(*filename);
const char *file_str = PyString_AsString(*filename);
- if (file_str == NULL || (len < 0 && PyErr_Occurred()))
+ if (file_str == NULL || (len < 0 && PyErr_Occurred()))
goto handle_error;
/* if filename.lower().endswith((".pyc", ".pyo")): */
@@ -506,10 +506,10 @@
tolower(file_str[len-1]) == 'o'))
{
*filename = PyString_FromStringAndSize(file_str, len-1);
- if (*filename == NULL)
- goto handle_error;
- }
- else
+ if (*filename == NULL)
+ goto handle_error;
+ }
+ else
Py_INCREF(*filename);
}
else {
@@ -536,8 +536,8 @@
else {
/* embedded interpreters don't have sys.argv, see bug #839151 */
*filename = PyString_FromString("__main__");
- if (*filename == NULL)
- goto handle_error;
+ if (*filename == NULL)
+ goto handle_error;
}
}
if (*filename == NULL) {
@@ -839,26 +839,29 @@
static PyObject *
init_filters(void)
{
- PyObject *filters = PyList_New(3);
+ PyObject *filters = PyList_New(4);
const char *bytes_action;
if (filters == NULL)
return NULL;
PyList_SET_ITEM(filters, 0,
+ create_filter(PyExc_DeprecationWarning, "ignore"));
+ PyList_SET_ITEM(filters, 1,
create_filter(PyExc_PendingDeprecationWarning, "ignore"));
- PyList_SET_ITEM(filters, 1, create_filter(PyExc_ImportWarning, "ignore"));
+ PyList_SET_ITEM(filters, 2, create_filter(PyExc_ImportWarning, "ignore"));
if (Py_BytesWarningFlag > 1)
bytes_action = "error";
else if (Py_BytesWarningFlag)
bytes_action = "default";
else
bytes_action = "ignore";
- PyList_SET_ITEM(filters, 2, create_filter(PyExc_BytesWarning,
+ PyList_SET_ITEM(filters, 3, create_filter(PyExc_BytesWarning,
bytes_action));
if (PyList_GET_ITEM(filters, 0) == NULL ||
PyList_GET_ITEM(filters, 1) == NULL ||
- PyList_GET_ITEM(filters, 2) == NULL) {
+ PyList_GET_ITEM(filters, 2) == NULL ||
+ PyList_GET_ITEM(filters, 3) == NULL) {
Py_DECREF(filters);
return NULL;
}