Add _showwarnmsg() and _formatwarnmsg() to warnings
Issue #26568: add new _showwarnmsg() and _formatwarnmsg() functions to the
warnings module.
The C function warn_explicit() now calls warnings._showwarnmsg() with a
warnings.WarningMessage as parameter, instead of calling warnings.showwarning()
with multiple parameters.
_showwarnmsg() calls warnings.showwarning() if warnings.showwarning() was
replaced. Same for _formatwarnmsg(): call warnings.formatwarning() if it was
replaced.
diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py
index cea9c57..70eae4c 100644
--- a/Lib/test/test_warnings/__init__.py
+++ b/Lib/test/test_warnings/__init__.py
@@ -651,6 +651,17 @@
result = stream.getvalue()
self.assertIn(text, result)
+ def test_showwarnmsg_missing(self):
+ # Test that _showwarnmsg() missing is okay.
+ text = 'del _showwarnmsg test'
+ with original_warnings.catch_warnings(module=self.module):
+ self.module.filterwarnings("always", category=UserWarning)
+ del self.module._showwarnmsg
+ with support.captured_output('stderr') as stream:
+ self.module.warn(text)
+ result = stream.getvalue()
+ self.assertIn(text, result)
+
def test_showwarning_not_callable(self):
with original_warnings.catch_warnings(module=self.module):
self.module.filterwarnings("always", category=UserWarning)
diff --git a/Lib/warnings.py b/Lib/warnings.py
index 1d4fb20..f54726a 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -6,24 +6,63 @@
"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.
+ msg = WarningMessage(message, category, filename, lineno, file, line)
+ _showwarnmsg(msg)
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(msg)
+
+# Keep references to check if the functions were replaced
+_showwarning = showwarning
+_formatwarning = formatwarning
+
+def _showwarnmsg(msg):
+ """Hook to write a warning to a file; replace if you like."""
+ showwarning = globals().get('showwarning', _showwarning)
+ if showwarning is not _showwarning:
+ # warnings.showwarning() was replaced
+ if not callable(showwarning):
+ raise TypeError("warnings.showwarning() must be set to a "
+ "function or method")
+
+ showwarning(msg.message, msg.category, msg.filename, msg.lineno,
+ msg.file, msg.line)
+ return
+
+ 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(msg):
+ """Function to format a warning the standard way."""
+ formatwarning = globals().get('formatwarning', _formatwarning)
+ if formatwarning is not _formatwarning:
+ # warnings.formatwarning() was replaced
+ return formatwarning(msg.message, msg.category,
+ msg.filename, msg.lineno, line=msg.line)
+
import linecache
- s = "%s:%s: %s: %s\n" % (filename, lineno, category.__name__, message)
- line = linecache.getline(filename, lineno) if line is None else line
+ s = ("%s:%s: %s: %s\n"
+ % (msg.filename, msg.lineno, msg.category.__name__,
+ msg.message))
+ if msg.line is None:
+ line = linecache.getline(msg.filename, msg.lineno)
+ else:
+ line = msg.line
if line:
line = line.strip()
s += " %s\n" % line
@@ -293,17 +332,13 @@
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)
+ msg = WarningMessage(message, category, filename, lineno)
+ _showwarnmsg(msg)
class WarningMessage(object):
- """Holds the result of a single showwarning() call."""
-
_WARNING_DETAILS = ("message", "category", "filename", "lineno", "file",
"line")
@@ -366,11 +401,12 @@
self._module.filters = self._filters[:]
self._module._filters_mutated()
self._showwarning = self._module.showwarning
+ self._showwarnmsg = self._module._showwarnmsg
if self._record:
log = []
- def showwarning(*args, **kwargs):
- log.append(WarningMessage(*args, **kwargs))
- self._module.showwarning = showwarning
+ def showarnmsg(msg):
+ log.append(msg)
+ self._module._showwarnmsg = showarnmsg
return log
else:
return None
@@ -381,6 +417,7 @@
self._module.filters = self._filters
self._module._filters_mutated()
self._module.showwarning = self._showwarning
+ self._module._showwarnmsg = self._showwarnmsg
# filters contains a sequence of filter 5-tuples
diff --git a/Python/_warnings.c b/Python/_warnings.c
index daa1355..a8c3703 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -359,6 +359,56 @@
PyErr_Clear();
}
+static int
+call_show_warning(PyObject *category, PyObject *text, PyObject *message,
+ PyObject *filename, int lineno, PyObject *lineno_obj,
+ PyObject *sourceline)
+{
+ PyObject *show_fn, *msg, *res, *warnmsg_cls = NULL;
+
+ show_fn = get_warnings_attr("_showwarnmsg");
+ if (show_fn == NULL) {
+ if (PyErr_Occurred())
+ return -1;
+ show_warning(filename, lineno, text, category, sourceline);
+ return 0;
+ }
+
+ if (!PyCallable_Check(show_fn)) {
+ PyErr_SetString(PyExc_TypeError,
+ "warnings._showwarnmsg() must be set to a callable");
+ goto error;
+ }
+
+ warnmsg_cls = get_warnings_attr("WarningMessage");
+ if (warnmsg_cls == NULL) {
+ PyErr_SetString(PyExc_RuntimeError,
+ "unable to get warnings.WarningMessage");
+ goto error;
+ }
+
+ msg = PyObject_CallFunctionObjArgs(warnmsg_cls, message, category,
+ filename, lineno_obj,
+ NULL);
+ Py_DECREF(warnmsg_cls);
+ if (msg == NULL)
+ goto error;
+
+ res = PyObject_CallFunctionObjArgs(show_fn, msg, NULL);
+ Py_DECREF(show_fn);
+ Py_DECREF(msg);
+
+ if (res == NULL)
+ return -1;
+
+ Py_DECREF(res);
+ return 0;
+
+error:
+ Py_XDECREF(show_fn);
+ return -1;
+}
+
static PyObject *
warn_explicit(PyObject *category, PyObject *message,
PyObject *filename, int lineno,
@@ -470,31 +520,9 @@
if (rc == 1) /* Already warned for this module. */
goto return_none;
if (rc == 0) {
- PyObject *show_fxn = get_warnings_attr("showwarning");
- if (show_fxn == NULL) {
- if (PyErr_Occurred())
- goto cleanup;
- show_warning(filename, lineno, text, category, sourceline);
- }
- else {
- PyObject *res;
-
- if (!PyCallable_Check(show_fxn)) {
- PyErr_SetString(PyExc_TypeError,
- "warnings.showwarning() must be set to a "
- "callable");
- Py_DECREF(show_fxn);
- goto cleanup;
- }
-
- res = PyObject_CallFunctionObjArgs(show_fxn, message, category,
- filename, lineno_obj,
- NULL);
- Py_DECREF(show_fxn);
- Py_XDECREF(res);
- if (res == NULL)
- goto cleanup;
- }
+ if (call_show_warning(category, text, message, filename, lineno,
+ lineno_obj, sourceline) < 0)
+ goto cleanup;
}
else /* if (rc == -1) */
goto cleanup;