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:标准库中是否有标准装饰器?
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:标准库中是否有标准装饰器?
这是一些片段,根据 Leandro 引用的片段进行了修改:
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,第一个暴露的解决方案(没有过滤器处理)可能会导致警告抑制。
这是另一个解决方案:
这个装饰器(实际上是一个装饰器工厂)允许你给出一个原因信息。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:它将warnings.warn_explicit
line by替换warnings.warn(msg, category=DeprecationWarning, stacklevel=2)
为打印函数调用站点而不是函数定义站点。它使调试更容易。
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:这个装饰器现在是弃用库的一部分:
新的稳定版本 v1.2.13
正如 muon 建议的那样,您可以deprecation
为此安装软件包。
该
deprecation
库为您的测试提供了一个deprecated
装饰器和一个装饰器。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
有关完整文档,请参阅http://deprecation.readthedocs.io/。
我猜原因是 Python 代码不能被静态处理(就像它对 C++ 编译器所做的那样),在实际使用它之前你不会收到关于使用某些东西的警告。我认为向您的脚本用户发送大量消息“警告:此脚本的此开发人员正在使用已弃用的 API”向用户发送垃圾邮件并不是一个好主意。
更新:但是您可以创建将原始功能转换为另一个功能的装饰器。新功能将标记/检查开关,告知该功能已被调用,并且仅在将开关变为开启状态时才会显示消息。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 deprecation 装饰器,如下所示:
from .utils import deprecated
@deprecated("Use method yyy instead")
def some_method()"
pass
更新:我认为更好的是,当我们只为每个代码行第一次显示 DeprecationWarning并且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
我们只需点击警告路径并转到 PyCharm 中的行。
Python
是一种动态类型语言。不必将类型静态声明为函数的变量或参数类型。
由于它是动态的,如果在运行时处理每件事。即使一个方法已被弃用,它也会在运行时或仅在解释期间知道。
使用弃用模块来弃用方法。
deprecation 是一个支持自动弃用的库。它提供deprecated()装饰器来包装函数,在文档中和通过 Python 的警告系统提供适当的警告,以及用于测试方法的deprecation.fail_if_not_removed()装饰器以确保最终删除不推荐使用的代码。
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