291 lines
9.3 KiB
Python
291 lines
9.3 KiB
Python
'''
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Utils
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=====
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'''
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__all__ = ('platform', 'reify', 'deprecated')
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from os import environ
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from os import path
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from sys import platform as _sys_platform
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import sys
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class Platform:
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'''
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Refactored to class to allow module function to be replaced
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with module variable.
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'''
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def __init__(self):
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self._platform_ios = None
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self._platform_android = None
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def __eq__(self, other):
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return other == self._get_platform()
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def __ne__(self, other):
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return other != self._get_platform()
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def __str__(self):
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return self._get_platform()
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def __repr__(self):
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return 'platform name: \'{platform}\' from: \n{instance}'.format(
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platform=self._get_platform(),
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instance=super().__repr__()
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)
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def __hash__(self):
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return self._get_platform().__hash__()
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def _get_platform(self):
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if self._platform_android is None:
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# sys.getandroidapilevel is defined as of Python 3.7
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# ANDROID_ARGUMENT and ANDROID_PRIVATE are 2 environment variables
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# from python-for-android project
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self._platform_android = hasattr(sys, 'getandroidapilevel') or \
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'ANDROID_ARGUMENT' in environ
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if self._platform_ios is None:
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self._platform_ios = (environ.get('KIVY_BUILD', '') == 'ios')
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# On android, _sys_platform return 'linux2', so prefer to check the
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# import of Android module than trying to rely on _sys_platform.
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if self._platform_android is True:
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return 'android'
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elif self._platform_ios is True:
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return 'ios'
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elif _sys_platform in ('win32', 'cygwin'):
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return 'win'
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elif _sys_platform == 'darwin':
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return 'macosx'
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elif _sys_platform[:5] == 'linux':
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return 'linux'
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return 'unknown'
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platform = Platform()
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class Proxy:
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'''
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Based on http://code.activestate.com/recipes/496741-object-proxying
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version by Tomer Filiba, PSF license.
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'''
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__slots__ = ['_obj', '_name', '_facade']
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def __init__(self, name, facade):
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object.__init__(self)
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object.__setattr__(self, '_obj', None)
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object.__setattr__(self, '_name', name)
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object.__setattr__(self, '_facade', facade)
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def _ensure_obj(self):
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obj = object.__getattribute__(self, '_obj')
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if obj:
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return obj
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# do the import
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try:
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name = object.__getattribute__(self, '_name')
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module = 'plyer.platforms.{}.{}'.format(
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platform, name)
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mod = __import__(module, fromlist='.')
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obj = mod.instance()
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except Exception:
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import traceback
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traceback.print_exc()
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facade = object.__getattribute__(self, '_facade')
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obj = facade()
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object.__setattr__(self, '_obj', obj)
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return obj
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def __getattribute__(self, name):
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result = None
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if name == '__doc__':
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return result
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# run _ensure_obj func, result in _obj
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object.__getattribute__(self, '_ensure_obj')()
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# return either Proxy instance or platform-dependent implementation
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result = getattr(object.__getattribute__(self, '_obj'), name)
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return result
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def __delattr__(self, name):
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object.__getattribute__(self, '_ensure_obj')()
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delattr(object.__getattribute__(self, '_obj'), name)
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def __setattr__(self, name, value):
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object.__getattribute__(self, '_ensure_obj')()
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setattr(object.__getattribute__(self, '_obj'), name, value)
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def __bool__(self):
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object.__getattribute__(self, '_ensure_obj')()
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return bool(object.__getattribute__(self, '_obj'))
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def __str__(self):
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object.__getattribute__(self, '_ensure_obj')()
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return str(object.__getattribute__(self, '_obj'))
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def __repr__(self):
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object.__getattribute__(self, '_ensure_obj')()
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return repr(object.__getattribute__(self, '_obj'))
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def whereis_exe(program):
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''' Tries to find the program on the system path.
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Returns the path if it is found or None if it's not found.
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'''
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path_split = ';' if platform == 'win' else ':'
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for pth in environ.get('PATH', '').split(path_split):
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folder = path.isdir(path.join(pth, program))
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available = path.exists(path.join(pth, program))
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if available and not folder:
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return path.join(pth, program)
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return None
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class reify:
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'''
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Put the result of a method which uses this (non-data) descriptor decorator
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in the instance dict after the first call, effectively replacing the
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decorator with an instance variable.
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It acts like @property, except that the function is only ever called once;
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after that, the value is cached as a regular attribute. This gives you lazy
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attribute creation on objects that are meant to be immutable.
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Taken from the `Pyramid project <https://pypi.python.org/pypi/pyramid/>`_.
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To use this as a decorator::
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@reify
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def lazy(self):
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...
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return hard_to_compute_int
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first_time = self.lazy # lazy is reify obj, reify.__get__() runs
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second_time = self.lazy # lazy is hard_to_compute_int
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'''
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def __init__(self, func):
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self.func = func
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self.__doc__ = func.__doc__
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def __get__(self, inst, cls):
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if inst is None:
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return self
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retval = self.func(inst)
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setattr(inst, self.func.__name__, retval)
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return retval
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def deprecated(obj):
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'''
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This is a decorator which can be used to mark functions and classes as
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deprecated. It will result in a warning being emitted when a deprecated
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function is called or a new instance of a class created.
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In case of classes, the warning is emitted before the __new__ method
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of the decorated class is called, therefore a way before the __init__
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method itself.
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'''
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import warnings
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from inspect import stack
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from functools import wraps
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from types import FunctionType, MethodType
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new_obj = None
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# wrap a function into a function emitting a deprecated warning
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if isinstance(obj, FunctionType):
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@wraps(obj)
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def new_func(*args, **kwargs):
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# get the previous stack frame and extract file, line and caller
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# stack() -> caller()
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call_file, call_line, caller = stack()[1][1:4]
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# assemble warning
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warning = (
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'Call to deprecated function {} in {} line {}. '
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'Called from {} line {}'
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' by {}().\n'.format(
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obj.__name__,
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obj.__code__.co_filename,
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obj.__code__.co_firstlineno + 1,
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call_file, call_line, caller
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)
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)
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warnings.warn('[{}] {}'.format('WARNING', warning))
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# if there is a docstring present, emit docstring too
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if obj.__doc__:
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warnings.warn(obj.__doc__)
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# return function wrapper
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return obj(*args, **kwargs)
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new_obj = new_func
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# wrap a class into a class emitting a deprecated warning
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# obj is class, type(obj) is metaclass, metaclasses inherit from type
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elif isinstance(type(obj), type):
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# we have an access to the metaclass instance (class) and need to print
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# the warning when a class instance (object) is created with __new__
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# i.e. when calling Class()
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def obj_new(cls, child, *args, **kwargs):
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'''
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Custom metaclass instance's __new__ method with deprecated warning.
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Calls the original __new__ method afterwards.
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'''
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# get the previous stack frame and extract file, line and caller
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# stack() -> caller()
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call_file, call_line, caller = stack()[1][1:4]
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loc_file = obj.__module__
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warnings.warn(
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'[{}] Creating an instance of a deprecated class {} in {}.'
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' Called from {} line {} by {}().\n'.format(
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'WARNING', obj.__name__, loc_file,
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call_file, call_line, caller
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)
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)
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# if there is a docstring present, emit docstring too
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if obj.__doc__:
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warnings.warn(obj.__doc__)
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# make sure nothing silly gets into the function
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assert obj is cls
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# we are creating a __new__ for a class that inherits from
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# a deprecated class, therefore in this particular case
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# MRO is (child, cls, object) > (cls, object)
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if len(child.__mro__) > len(cls.__mro__):
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assert cls is child.__mro__[1], (cls.__mro__, child.__mro__)
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# we are creating __new__ directly for the deprecated class
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# therefore MRO is the same for parent and child class
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elif len(child.__mro__) == len(cls.__mro__):
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assert cls is child
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# return the class back with the extended __new__ method
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return obj.__old_new__(child)
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# back up the old __new__ method and create an extended
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# __new__ method that emits deprecated warnings
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obj.__old_new__ = obj.__new__
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obj.__new__ = MethodType(obj_new, obj)
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new_obj = obj
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# return a function wrapper or an extended class
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return new_obj
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