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Showing content from http://mail.python.org/pipermail/python-dev/attachments/20100110/db6da5fd/attachment-0007.htm below:

Nick Coghlan thought I should forward this to python-dev so people are aware of this change and why it occurred (plus it indirectly informs Guido I finally finished the work). <div class="gmail_quote">---------- Forwarded message ----------

From: brett.cannon <<a href="mailto:python-checkins@python.org">python-checkins@python.org</a>> Date: Sat, Jan 9, 2010 at 18:56 Subject: [Python-checkins] r77402 - in python/trunk: Doc/library/warnings.rst Lib/test/test_ascii_formatd.py Lib/test/test_exceptions.py Lib/warnings.py Misc/NEWS Python/_warnings.c

To: <a href="mailto:python-checkins@python.org">python-checkins@python.org</a> Author: brett.cannon

Date: Sun Jan 10 03:56:19 2010 
New Revision: 77402 
 
Log: 
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. 
 
 
Modified: 
Â python/trunk/Doc/library/warnings.rst 
Â python/trunk/Lib/test/test_ascii_formatd.py 
Â python/trunk/Lib/test/test_exceptions.py 
Â python/trunk/Lib/warnings.py 
Â python/trunk/Misc/NEWS 
Â python/trunk/Python/_warnings.c 
 
Modified: python/trunk/Doc/library/warnings.rst 
============================================================================== 
--- python/trunk/Doc/library/warnings.rst Â Â Â (original) 
+++ python/trunk/Doc/library/warnings.rst Â Â Â Sun Jan 10 03:56:19 2010 
@@ -59,7 +59,7 @@ 
Â | :exc:`UserWarning` Â Â Â Â Â Â Â | The default category for :func:`warn`. Â Â Â Â | 
Â +----------------------------------+-----------------------------------------------+ 
Â | :exc:`DeprecationWarning` Â Â Â Â | Base category for warnings about deprecated Â | 
-| Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â | features. Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â | 
+| Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â | features (ignored by default). Â Â Â Â Â Â Â Â | 
Â +----------------------------------+-----------------------------------------------+ 
Â | :exc:`SyntaxWarning` Â Â Â Â Â Â | Base category for warnings about dubious Â Â Â | 
Â | Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â | syntactic features. Â Â Â Â Â Â Â Â Â Â Â Â Â | 
@@ -89,6 +89,9 @@ 
Â standard warning categories. Â A warning category must always be a subclass of 
Â the :exc:`Warning` class. 
 
+.. versionchanged:: 2.7 
+ Â :exc:`DeprecationWarning` is ignored by default. 
+ 
 
Â .. _warning-filter: 
 
@@ -148,14 +151,6 @@ 
Â :mod:`warnings` module parses these when it is first imported (invalid options 
Â 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:: 
- 
- Â warnings.simplefilter('default', ImportWarning) 
- 
 
Â .. _warning-suppress: 
 
@@ -226,6 +221,37 @@ 
Â 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`). Â 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:: 
+ 
+ Â 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. Â 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. 
+ 
+ 
Â .. _warning-functions: 
 
Â Available Functions 
 
Modified: python/trunk/Lib/test/test_ascii_formatd.py 
============================================================================== 
--- python/trunk/Lib/test/test_ascii_formatd.py (original) 
+++ python/trunk/Lib/test/test_ascii_formatd.py Sun Jan 10 03:56:19 2010 
@@ -4,6 +4,7 @@ 
 
Â import unittest 
Â from test_support import check_warnings, run_unittest, cpython_only 
+import warnings 
 
 
Â class FormatDeprecationTests(unittest.TestCase): 
@@ -17,6 +18,7 @@ 
Â Â Â Â buf = create_string_buffer(' ' * 100) 
 
Â Â Â Â with check_warnings() as w: 
+ Â Â Â Â Â Â warnings.simplefilter('default') 
Â Â Â Â Â Â PyOS_ascii_formatd(byref(buf), sizeof(buf), '%+.10f', 
Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â c_double(10.0)) 
Â Â Â Â Â Â self.assertEqual(buf.value, '+10.0000000000') 
 
Modified: python/trunk/Lib/test/test_exceptions.py 
============================================================================== 
--- python/trunk/Lib/test/test_exceptions.py Â Â (original) 
+++ python/trunk/Lib/test/test_exceptions.py Â Â Sun Jan 10 03:56:19 2010 
@@ -309,6 +309,7 @@ 
Â Â Â Â # BaseException.__init__ triggers a deprecation warning. 
Â Â Â Â exc = BaseException("foo") 
Â Â Â Â with warnings.catch_warnings(record=True) as w: 
+ Â Â Â Â Â Â warnings.simplefilter('default') 
Â Â Â Â Â Â self.assertEquals(exc.message, "foo") 
Â Â Â Â self.assertEquals(len(w), 1) 
Â Â Â Â self.assertEquals(w[0].category, DeprecationWarning) 
 
Modified: python/trunk/Lib/warnings.py 
============================================================================== 
--- python/trunk/Lib/warnings.py Â Â Â Â (original) 
+++ python/trunk/Lib/warnings.py Â Â Â Â Sun Jan 10 03:56:19 2010 
@@ -383,8 +383,8 @@ 
Â # Module initialization 
Â _processoptions(sys.warnoptions) 
Â if not _warnings_defaults: 
- Â Â simplefilter("ignore", category=PendingDeprecationWarning, append=1) 
- Â Â simplefilter("ignore", category=ImportWarning, append=1) 
+ Â Â for cls in (DeprecationWarning, PendingDeprecationWarning, ImportWarning): 
+ Â Â Â Â simplefilter("ignore", category=cls, append=True) 
Â Â bytes_warning = sys.flags.bytes_warning 
Â Â if bytes_warning > 1: 
Â Â Â Â bytes_action = "error" 
 
Modified: python/trunk/Misc/NEWS 
============================================================================== 
--- python/trunk/Misc/NEWS Â Â Â (original) 
+++ python/trunk/Misc/NEWS Â Â Â Sun Jan 10 03:56:19 2010 
@@ -12,6 +12,8 @@ 
Â Core and Builtins 
Â ----------------- 
 
+- Issue #7319: Silence DeprecationWarning by default. 
+ 
Â - Issue #2335: Backport set literals syntax from Python 3.x. 
 
Â Library 
 
Modified: python/trunk/Python/_warnings.c 
============================================================================== 
--- python/trunk/Python/_warnings.c Â Â (original) 
+++ python/trunk/Python/_warnings.c Â Â Sun Jan 10 03:56:19 2010 
@@ -85,10 +85,10 @@ 
 
Â Â default_action = get_warnings_attr("defaultaction"); 
Â Â if (default_action == NULL) { 
- Â Â Â if (PyErr_Occurred()) { 
- Â Â Â Â Â return NULL; 
- Â Â Â } 
- Â Â Â return _default_action; 
+ Â Â Â Â if (PyErr_Occurred()) { 
+ Â Â Â Â Â Â return NULL; 
+ Â Â Â Â } 
+ Â Â Â Â return _default_action; 
Â Â } 
 
Â Â Py_DECREF(_default_action); 
@@ -202,12 +202,12 @@ 
 
Â Â mod_str = PyString_AsString(filename); 
Â Â if (mod_str == NULL) 
- Â Â Â Â Â return NULL; 
+ Â Â Â Â return NULL; 
Â Â len = PyString_Size(filename); 
Â Â if (len < 0) 
Â Â Â Â return NULL; 
Â Â if (len >= 3 && 
- Â Â Â strncmp(mod_str + (len - 3), ".py", 3) == 0) { 
+ Â Â Â Â Â Â strncmp(mod_str + (len - 3), ".py", 3) == 0) { 
Â Â Â Â module = PyString_FromStringAndSize(mod_str, len-3); 
Â Â } 
Â Â else { 
@@ -251,7 +251,7 @@ 
 
Â Â name = PyObject_GetAttrString(category, "__name__"); 
Â Â if (name == NULL) Â /* XXX Can an object lack a '__name__' attribute? */ 
- Â Â Â Â Â return; 
+ Â Â Â Â return; 
 
Â Â f_stderr = PySys_GetObject("stderr"); 
Â Â if (f_stderr == NULL) { 
@@ -341,7 +341,7 @@ 
Â Â Â Â rc = already_warned(registry, key, 0); 
Â Â Â Â if (rc == -1) 
Â Â Â Â Â Â goto cleanup; 
- Â Â Â else if (rc == 1) 
+ Â Â Â Â else if (rc == 1) 
Â Â Â Â Â Â goto return_none; 
Â Â Â Â /* Else this warning hasn't been generated before. */ 
Â Â } 
@@ -492,9 +492,9 @@ 
Â Â /* Setup filename. */ 
Â Â *filename = PyDict_GetItemString(globals, "__file__"); 
Â Â if (*filename != NULL) { 
- Â Â Â Â Â Py_ssize_t len = PyString_Size(*filename); 
+ Â Â Â Â Â Â Py_ssize_t len = PyString_Size(*filename); 
Â Â Â Â const char *file_str = PyString_AsString(*filename); 
- Â Â Â Â Â if (file_str == NULL || (len < 0 && PyErr_Occurred())) 
+ Â Â Â Â Â Â if (file_str == NULL || (len < 0 && PyErr_Occurred())) 
Â Â Â Â Â Â goto handle_error; 
 
Â Â Â Â /* if filename.lower().endswith((".pyc", ".pyo")): */ 
@@ -506,10 +506,10 @@ 
Â Â Â Â Â Â Â Â tolower(file_str[len-1]) == 'o')) 
Â Â Â Â { 
Â Â Â Â Â Â *filename = PyString_FromStringAndSize(file_str, len-1); 
- Â Â Â Â Â Â Â if (*filename == NULL) 
- Â Â Â Â Â Â Â Â Â Â Â goto handle_error; 
- Â Â Â Â Â } 
- Â Â Â Â Â else 
+ Â Â Â Â Â Â if (*filename == NULL) 
+ Â Â Â Â Â Â Â Â goto handle_error; 
+ Â Â Â Â } 
+ Â Â Â Â else 
Â Â Â Â Â Â Py_INCREF(*filename); 
Â Â } 
Â Â else { 
@@ -536,8 +536,8 @@ 
Â Â Â Â Â Â else { 
Â Â Â Â Â Â Â Â /* embedded interpreters don't have sys.argv, see bug #839151 */ 
Â Â Â Â Â Â Â Â *filename = PyString_FromString("__main__"); 
- Â Â Â Â Â Â Â Â Â if (*filename == NULL) 
- Â Â Â Â Â Â Â Â Â Â Â goto handle_error; 
+ Â Â Â Â Â Â Â Â if (*filename == NULL) 
+ Â Â Â Â Â Â Â Â Â Â goto handle_error; 
Â Â Â Â Â Â } 
Â Â Â Â } 
Â Â Â Â if (*filename == NULL) { 
@@ -839,26 +839,29 @@ 
Â static PyObject * 
Â init_filters(void) 
Â { 
- Â Â PyObject *filters = PyList_New(3); 
+ Â Â PyObject *filters = PyList_New(4); 
Â Â const char *bytes_action; 
Â Â if (filters == NULL) 
Â Â Â Â return NULL; 
 
Â Â PyList_SET_ITEM(filters, 0, 
+ Â Â Â Â Â Â Â Â Â Â create_filter(PyExc_DeprecationWarning, "ignore")); 
+ Â Â PyList_SET_ITEM(filters, 1, 
Â Â Â Â Â Â Â Â Â Â create_filter(PyExc_PendingDeprecationWarning, "ignore")); 
- Â Â PyList_SET_ITEM(filters, 1, create_filter(PyExc_ImportWarning, "ignore")); 
+ Â Â PyList_SET_ITEM(filters, 2, create_filter(PyExc_ImportWarning, "ignore")); 
Â Â if (Py_BytesWarningFlag > 1) 
Â Â Â Â bytes_action = "error"; 
Â Â else if (Py_BytesWarningFlag) 
Â Â Â Â bytes_action = "default"; 
Â Â else 
Â Â Â Â bytes_action = "ignore"; 
- Â Â PyList_SET_ITEM(filters, 2, create_filter(PyExc_BytesWarning, 
+ Â Â PyList_SET_ITEM(filters, 3, create_filter(PyExc_BytesWarning, 
Â Â Â Â Â Â Â Â Â Â bytes_action)); 
 
Â Â if (PyList_GET_ITEM(filters, 0) == NULL || 
Â Â Â Â PyList_GET_ITEM(filters, 1) == NULL || 
- Â Â Â Â PyList_GET_ITEM(filters, 2) == NULL) { 
+ Â Â Â Â PyList_GET_ITEM(filters, 2) == NULL || 
+ Â Â Â Â PyList_GET_ITEM(filters, 3) == NULL) { 
Â Â Â Â Py_DECREF(filters); 
Â Â Â Â return NULL; 
<div><div></div><div class="h5"> Â Â } 
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