summaryrefslogtreecommitdiffstats
path: root/Lib/warnings.py
blob: 5badb0be3763fd0ecd8267e78115681ba7fa1c37 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
"""Python part of the warnings subsystem."""

import sys


__all__ = ["warn", "warn_explicit", "showwarning",
           "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."""
    msg = WarningMessage(message, category, filename, lineno, file, line)
    _showwarnmsg_impl(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_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):
    s =  ("%s:%s: %s: %s\n"
          % (msg.filename, msg.lineno, msg.category.__name__,
             msg.message))

    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
            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 first):\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
    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, line=msg.line)
    return _formatwarnmsg_impl(msg)

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
    """
    import re
    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"
    _add_filter(action, re.compile(message, re.I), category,
            re.compile(module), lineno, append=append)

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()

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):
    import re
    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)
    message = re.escape(message)
    category = _getcategory(category)
    module = re.escape(module)
    if module:
        module = module + '$'
    if lineno:
        try:
            lineno = int(lineno)
            if lineno < 0:
                raise ValueError
        except (ValueError, OverflowError):
            raise _OptionError("invalid lineno %r" % (lineno,))
    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):
    import re
    if not category:
        return Warning
    if re.match("^[a-zA-Z0-9_]+$", category):
        try:
            cat = eval(category)
        except NameError:
            raise _OptionError("unknown warning category: %r" % (category,))
    else:
        i = category.rfind(".")
        module = category[:i]
        klass = category[i+1:]
        try:
            m = __import__(module, None, None, [klass])
        except ImportError:
            raise _OptionError("invalid module name: %r" % (module,))
        try:
            cat = getattr(m, klass)
        except AttributeError:
            raise _OptionError("unknown warning category: %r" % (category,))
    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__
        lineno = 1
    else:
        globals = frame.f_globals
        lineno = frame.f_lineno
    if '__name__' in globals:
        module = globals['__name__']
    else:
        module = "<string>"
    filename = globals.get('__file__')
    if filename:
        fnl = filename.lower()
        if fnl.endswith(".pyc"):
            filename = filename[:-1]
    else:
        if module == "__main__":
            try:
                filename = sys.argv[0]
            except AttributeError:
                # embedded interpreters don't have sys.argv, see bug #839151
                filename = '__main__'
        if not filename:
            filename = module
    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":
        registry[key] = 1
        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):
        local_values = locals()
        for attr in self._WARNING_DETAILS:
            setattr(self, attr, local_values[attr])
        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))


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


# 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.
_warnings_defaults = False
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


# Module initialization
_processoptions(sys.warnoptions)
if not _warnings_defaults:
    silence = [ImportWarning, PendingDeprecationWarning]
    silence.append(DeprecationWarning)
    for cls in silence:
        simplefilter("ignore", category=cls)
    bytes_warning = sys.flags.bytes_warning
    if bytes_warning > 1:
        bytes_action = "error"
    elif bytes_warning:
        bytes_action = "default"
    else:
        bytes_action = "ignore"
    simplefilter(bytes_action, category=BytesWarning, append=1)
    # resource usage warnings are enabled by default in pydebug mode
    if hasattr(sys, 'gettotalrefcount'):
        resource_action = "always"
    else:
        resource_action = "ignore"
    simplefilter(resource_action, category=ResourceWarning, append=1)

del _warnings_defaults