# -*- coding: utf-8 -*-
# -----------------------------------------------------------------------------
# (C) British Crown Copyright 2017-2019 Met Office.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# * Neither the name of the copyright holder nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
"""Classes and functions for managing warnings in the IMPROVER code."""
import sys
import warnings
[docs]class ManageWarnings:
"""
A decorator used to manage the warnings that are raised by a function.
Ignore a selection of warnings, and either raise any remaining warnings
to standard error or record them in a list of warning objects.
"""
[docs] def __init__(self, ignored_messages=None, warning_types=None,
record=False):
"""
Set up a decorator with the warnings we want to ignore and what
we want to do with any remaining warnings.
Args:
ignored_messages (list of str):
A list of messages, one for each warning message we
want to ignore.
warning_types (list):
A list containing the Warning category for each of the
messages. If not provided then the Warning Category is
assumed to be UserWarning for each of the messages.
record (bool):
A flag for whether to store any warnings that are not
ignored. Default is False which means warnings go to
standard error. When set to True the warnings are
recorded in a warning list which is passed to the function
being decorated.
Raises:
TypeError: ignored_messages not list.
ValueError: Raise error if both ignored messages and warning_types
are given and they are not the same length.
"""
if ignored_messages is not None:
if not isinstance(ignored_messages, list):
msg = 'Expecting list of strings for ignored_messages'
raise TypeError(msg)
self.messages = ignored_messages
if warning_types is None and self.messages is not None:
self.warning_types = [UserWarning for _ in self.messages]
else:
self.warning_types = warning_types
self.record = record
if self.messages and (len(self.warning_types) != len(self.messages)):
message = ("Length of warning_types ({}) does no equal length"
"of warning messages({})")
message = message.format(len(self.warning_types),
len(self.messages))
raise ValueError(message)
[docs] @staticmethod
def reset_warning_registry():
"""
Clears the hidden __warningregistry__ attribute from
all imported modules.
"""
for mod in list(sys.modules.values()):
if hasattr(mod, '__warningregistry__'):
mod.__warningregistry__.clear()
def __call__(self, func):
"""
Call the decorator on a function.
Wrap the function in the warnings.catch_warnings context manager
and set up the filters to ignore the specified warnings.
If we are recording the warnings, the list of warnings is passed
to the input function as a keyword argument for checking if
required.
Args:
func (function):
A function that we want to wrap with this decorator.
Returns:
function:
The wrapped function with the warnings context manager and
necessary filters turned on.
"""
def warnings_wrapper(*args, **kwargs):
"""
Wrapper function to set up the warnings.catch_warnings context
manager and the filters before calling the input function, with
the warning_list if needed.
"""
with warnings.catch_warnings(record=self.record) as warning_list:
warnings.filterwarnings("always")
self.reset_warning_registry()
if self.messages is not None:
for message, warning_type in zip(self.messages,
self.warning_types):
warnings.filterwarnings("ignore", message,
warning_type)
if self.record:
result = func(*args, warning_list=warning_list, **kwargs)
else:
result = func(*args, **kwargs)
self.reset_warning_registry()
return result
return warnings_wrapper