# coding: utf-8
# ------------------------------------------------------------------------------
# Copyright (C) 2019 Maximilian Stahlberg
#
# This file is part of PICOS.
#
# PICOS is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# PICOS is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# ------------------------------------------------------------------------------
"""Python 2/3 compatibility helpers."""
import sys
from abc import ABCMeta
from abc import abstractmethod as _abstractmethod
from copy import copy
from .apidoc import api_end, api_start
_API_START = api_start(globals())
# -------------------------------
VERSION = sys.version_info #: The same as :obj:`sys.version_info`.
MAJOR = VERSION.major #: Major Python version.
MINOR = VERSION.minor #: Minor Python version.
# Import the 'builtins' module for both Pythons.
if MAJOR >= 3:
import builtins # noqa
else:
import __builtin__ as builtins # noqa
# Import 'MutableSet' for both Pythons.
if MAJOR >= 3:
from collections.abc import MutableSet # noqa
else:
from collections import MutableSet # noqa
# Allow the long type to be referenced in Python 3.
long = int if MAJOR >= 3 else long # noqa
# Import abstract base class support for both Pythons.
ABC = ABCMeta("ABC", (object,), {"__slots__": ()})
ABC.__doc__ = "Base class for abstract classes."
abstractmethod = copy(_abstractmethod)
# HACK: Fix abstractmethod's docstring so Sphinx doesn't warn about it.
abstractmethod.__doc__ = "A decorator indicating abstract methods."
# TODO: Implement lru_cache for Python 2.
def _lru_cache(maxsize=128, typed=False):
def decorator(function):
def wrapper(*args, **kwargs):
return function(*args, **kwargs)
return wrapper
return decorator
# Make lru_cache available.
try:
from functools import lru_cache
except ImportError:
try:
from functools32 import lru_cache
except ImportError:
try:
from repoze.lru import lru_cache
except ImportError:
lru_cache = _lru_cache
# Import or implement MappingProxyType.
try:
from types import MappingProxyType
except ImportError: # Python < 3.3
from collections import Mapping as _Mapping
class MappingProxyType(_Mapping): # noqa
def __init__(self, mapping): # noqa
self._mapping = mapping
def __getitem__(self, key):
return self._mapping[key]
def __iter__(self):
return iter(self._mapping)
def __len__(self):
return len(self._mapping)
def copy(self): # noqa
return self._mapping.copy()
[docs]def import_exists(importName):
"""Check if a package or module name is available for import."""
if MAJOR >= 3:
if MINOR >= 4:
import importlib.util
return importlib.util.find_spec(importName) is not None
else:
import importlib
return importlib.find_loader(importName) is not None
else:
import pkgutil
return pkgutil.find_loader(importName) is not None
[docs]def assert_import_exists(importName):
"""Error if the given package or module name is not available for import.
:raises ModuleNotFoundError or ImportError: If no module with the given name
is available for import, denpending on the Python version.
"""
if not import_exists(importName):
if MAJOR >= 3:
Error = ModuleNotFoundError
else:
Error = ImportError
raise Error("Python module '{}' not found.".format(importName))
__all__ = api_end(_API_START, globals())