Python 标准库中的装饰器 (特别是@deprecated)

我猜原因是Python代码不能被静态处理(就像c++编译器那样)，在实际使用某些东西之前，你不能得到警告。我不认为这是一个好主意垃圾邮件用户你的脚本的一堆消息“警告:这个脚本的开发人员正在使用弃用的API”。

更新:，但是你可以创建decorator，它将原始函数转换为另一个函数。新函数将标记/检查开关，告诉该函数已被调用，并仅在开关进入打开状态时显示消息。和/或在退出时，它可以打印程序中使用的所有弃用函数的列表。

以下是一些摘录，是根据Leandro引用的内容修改的:

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

因为在一些解释器中，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。

这里有另一个解决方案:

这个装饰器(实际上是装饰器工厂)允许你给出一个原因消息。通过给源代码文件名和行号来帮助开发人员诊断问题也更有用。

编辑:这个代码使用Zero的建议:它用warnings.warn(msg, category=DeprecationWarning, stacklevel=2)替换warnings.warn_explicit行， 打印函数调用位置，而不是函数定义位置。

EDIT2:这个版本允许开发人员指定一个可选的“理由”;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)))

你可以对功能， 方法和类使用这个装饰器。

这里有一个简单的例子:

@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Deprecated库的一部分:

• Python包索引(PyPi
• GitHub website
• < a href = " http://deprecated.readthedocs。io/en/latest/" rel="noreferrer">阅读文档 . io/en/latest/" rel="noreferrer">
• Twitter

新的稳定版本v1.2.13🎉

更新:我认为更好，当我们只在每个代码行的第一次显示DeprecationWarning时，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

我们可以点击警告路径，然后在PyCharm中找到这一行。

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

然后导入已弃用的装饰器，如下所示:

from .utils import deprecated


@deprecated("Use method yyy instead")
def some_method()"
pass

正如μ子所说，你可以为此安装deprecation包。

deprecation库为你的测试提供了一个deprecated装饰器和一个fail_if_not_removed装饰器。

安装

pip install deprecation

示例使用

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

完整的文档请参见http://deprecation.readthedocs.io/。

Python是一个动态类型的语言。不需要静态地将类型声明为函数的变量或参数类型。

因为它是动态的，每件事都是在运行时处理的。即使一个方法被弃用，它也只会在运行时或解释期间被知道。

使用< >强弃用< / >强模块弃用方法。

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 在文档和Python的warnings系统中都有警告，例如 以及< a href = " https://deprecation.readthedocs.io/en/latest/弃用。fail_if_not_remove " rel="nofollow noreferrer"> deprecated .fail_if_not_remove ()装饰器进行测试 方法，以确保废弃的代码最终被删除

安装:

python3.10 -m pip install deprecation

小的演示:

import deprecation


@deprecation.deprecated(details="Use bar instead")
def foo():
print("Foo")




def bar():
print("Bar")




foo()


bar()

输出:

test.py: DeprecatedWarning: foo is deprecated. Use bar instead
foo()


Foo


Bar