我需要将例程标记为已弃用，但显然没有用于弃用的标准库装饰器。我知道它的配方和警告模块，但我的问题是：为什么这个（常见）任务没有标准库装饰器？
附加问题：标准库中有标准装饰器吗？
这是一些片段，根据 Leandro 引用的内容进行修改：
import warnings
import functools
def deprecated(func):
"""This is a decorator which can be used to mark functions
as deprecated. It will result in a warning being emitted
when the function is used."""
@functools.wraps(func)
def new_func(*args, **kwargs):
warnings.simplefilter('always', DeprecationWarning) # turn off filter
warnings.warn("Call to deprecated function {}.".format(func.__name__),
category=DeprecationWarning,
stacklevel=2)
warnings.simplefilter('default', DeprecationWarning) # reset filter
return func(*args, **kwargs)
return new_func
# Examples
@deprecated
def some_old_function(x, y):
return x + y
class SomeClass:
@deprecated
def some_old_method(self, x, y):
return x + y
因为在某些解释器中，暴露的第一个解决方案（没有过滤器处理）可能会导致警告抑制。
这是另一种解决方案：
这个装饰器（实际上是一个装饰器工厂）允许您给出原因消息。通过提供源文件名和行号来帮助开发人员诊断问题也更有用。
编辑：此代码使用 Zero 的建议：将
warnings.warn_explicitwarnings.warn(msg, category=DeprecationWarning, stacklevel=2)EDIT2：此版本允许开发人员指定可选的“原因”消息。
import functools
import inspect
import warnings
string_types = (type(b''), type(u''))
def deprecated(reason):
"""
This is a decorator which can be used to mark functions
as deprecated. It will result in a warning being emitted
when the function is used.
"""
if isinstance(reason, string_types):
# The @deprecated is used with a 'reason'.
#
# .. code-block:: python
#
# @deprecated("please, use another function")
# def old_function(x, y):
# pass
def decorator(func1):
if inspect.isclass(func1):
fmt1 = "Call to deprecated class {name} ({reason})."
else:
fmt1 = "Call to deprecated function {name} ({reason})."
@functools.wraps(func1)
def new_func1(*args, **kwargs):
warnings.simplefilter('always', DeprecationWarning)
warnings.warn(
fmt1.format(name=func1.__name__, reason=reason),
category=DeprecationWarning,
stacklevel=2
)
warnings.simplefilter('default', DeprecationWarning)
return func1(*args, **kwargs)
return new_func1
return decorator
elif inspect.isclass(reason) or inspect.isfunction(reason):
# The @deprecated is used without any 'reason'.
#
# .. code-block:: python
#
# @deprecated
# def old_function(x, y):
# pass
func2 = reason
if inspect.isclass(func2):
fmt2 = "Call to deprecated class {name}."
else:
fmt2 = "Call to deprecated function {name}."
@functools.wraps(func2)
def new_func2(*args, **kwargs):
warnings.simplefilter('always', DeprecationWarning)
warnings.warn(
fmt2.format(name=func2.__name__),
category=DeprecationWarning,
stacklevel=2
)
warnings.simplefilter('default', DeprecationWarning)
return func2(*args, **kwargs)
return new_func2
else:
raise TypeError(repr(type(reason)))
您可以将此装饰器用于函数、方法和类。
这是一个简单的例子：
@deprecated("use another function")
def some_old_function(x, y):
return x + y
class SomeClass(object):
@deprecated("use another method")
def some_old_method(self, x, y):
return x + y
@deprecated("use another class")
class SomeOldClass(object):
pass
some_old_function(5, 3)
SomeClass().some_old_method(8, 9)
SomeOldClass()
你会得到：
deprecated_example.py:59: DeprecationWarning: Call to deprecated function or method some_old_function (use another function).
some_old_function(5, 3)
deprecated_example.py:60: DeprecationWarning: Call to deprecated function or method some_old_method (use another method).
SomeClass().some_old_method(8, 9)
deprecated_example.py:61: DeprecationWarning: Call to deprecated class SomeOldClass (use another class).
SomeOldClass()
EDIT3： 这个装饰器现在是已弃用库的一部分：
新稳定版 v1.2.13 🎉
按照 muon 的建议，您可以为此安装
deprecation库为您的测试提供了一个deprecation装饰器和一个deprecated装饰器。fail_if_not_removed
pip install deprecation
import deprecation
@deprecation.deprecated(deprecated_in="1.0", removed_in="2.0",
current_version=__version__,
details="Use the bar function instead")
def foo():
"""Do some stuff"""
return 1
请参阅 http://deprecation.readthedocs.io/ 获取完整文档。
我猜原因是 Python 代码无法静态处理（就像 C++ 编译器所做的那样），在实际使用某些东西之前你无法收到有关使用某些东西的警告。我认为用一堆消息向脚本的用户发送垃圾邮件“警告：此脚本的开发人员正在使用已弃用的 API”并不是一个好主意。
更新：但是您可以创建装饰器，将原始函数转换为另一个函数。新函数将标记/检查开关，告知该函数已被调用，并且仅在将开关切换到打开状态时才显示消息。和/或在退出时，它可能会打印程序中使用的所有已弃用函数的列表。
您可以创建一个utils文件
import warnings
def deprecated(message):
def deprecated_decorator(func):
def deprecated_func(*args, **kwargs):
warnings.warn("{} is a deprecated function. {}".format(func.__name__, message),
category=DeprecationWarning,
stacklevel=2)
warnings.simplefilter('default', DeprecationWarning)
return func(*args, **kwargs)
return deprecated_func
return deprecated_decorator
然后导入弃用装饰器，如下所示：
from .utils import deprecated
@deprecated("Use method yyy instead")
def some_method():
pass
warnings.deprecatedmypy作为示例，请考虑名为library.pyi 的库存根：
from warnings import deprecated @deprecated("Use Spam instead") class Ham: ... @deprecated("It is pining for the fiords") def norwegian_blue(x: int) -> int: ... @overload @deprecated("Only str will be allowed") def foo(x: int) -> str: ... @overload def foo(x: str) -> str: ...以下是类型检查器应如何处理该库的使用：
from library import Ham # error: Use of deprecated class Ham. Use Spam instead. import library library.norwegian_blue(1) # error: Use of deprecated function norwegian_blue. It is pining for the fiords. map(library.norwegian_blue, [1, 2, 3]) # error: Use of deprecated function norwegian_blue. It is pining for the fiords. library.foo(1) # error: Use of deprecated overload for foo. Only str will be allowed. library.foo("x") # no error ham = Ham() # no error (already reported above)来源：PEP702
Python因为它是动态的，如果在运行时处理的话，一切都是动态的。即使某个方法已被弃用，它也会在运行时或仅在解释期间被知晓。
使用 deprecation 模块来弃用方法。
deprecation 是一个支持自动弃用的库。它 提供 deprecated() 装饰器来包装函数，提供适当的 文档中和通过 Python 的 warnings 系统发出警告，如 以及用于测试的 deprecation.fail_if_not_removed() 装饰器 确保最终删除不推荐使用的代码的方法。
python3.10 -m pip install deprecation
import deprecation
@deprecation.deprecated(details="Use bar instead")
def foo():
print("Foo")
def bar():
print("Bar")
foo()
bar()
test.py: DeprecatedWarning: foo is deprecated. Use bar instead
foo()
Foo
Bar
更新：我认为更好的是，当我们第一次为每个代码行显示 DeprecationWarning 时，以及当我们可以发送一些消息时：
import inspect
import traceback
import warnings
import functools
import time
def deprecated(message: str = ''):
"""
This is a decorator which can be used to mark functions
as deprecated. It will result in a warning being emitted
when the function is used first time and filter is set for show DeprecationWarning.
"""
def decorator_wrapper(func):
@functools.wraps(func)
def function_wrapper(*args, **kwargs):
current_call_source = '|'.join(traceback.format_stack(inspect.currentframe()))
if current_call_source not in function_wrapper.last_call_source:
warnings.warn("Function {} is now deprecated! {}".format(func.__name__, message),
category=DeprecationWarning, stacklevel=2)
function_wrapper.last_call_source.add(current_call_source)
return func(*args, **kwargs)
function_wrapper.last_call_source = set()
return function_wrapper
return decorator_wrapper
@deprecated('You must use my_func2!')
def my_func():
time.sleep(.1)
print('aaa')
time.sleep(.1)
def my_func2():
print('bbb')
warnings.simplefilter('always', DeprecationWarning) # turn off filter
print('before cycle')
for i in range(5):
my_func()
print('after cycle')
my_func()
my_func()
my_func()
结果：
before cycle
C:/Users/adr-0/OneDrive/Projects/Python/test/unit1.py:45: DeprecationWarning: Function my_func is now deprecated! You must use my_func2!
aaa
aaa
aaa
aaa
aaa
after cycle
C:/Users/adr-0/OneDrive/Projects/Python/test/unit1.py:47: DeprecationWarning: Function my_func is now deprecated! You must use my_func2!
aaa
C:/Users/adr-0/OneDrive/Projects/Python/test/unit1.py:48: DeprecationWarning: Function my_func is now deprecated! You must use my_func2!
aaa
C:/Users/adr-0/OneDrive/Projects/Python/test/unit1.py:49: DeprecationWarning: Function my_func is now deprecated! You must use my_func2!
aaa
Process finished with exit code 0
我们只需单击警告路径即可转到 PyCharm 中的行。