如何棄用Python函數？

Question

我需要將Python例程標記爲棄用，但我找不到用於棄用的標準庫裝飾器。我知道它的食譜和警告模塊，但我的問題是：

爲什麼在Python中沒有標準庫裝飾器用於棄用？

Answer 1

我想是因爲Python代碼不能靜態處理（就像它爲C++編譯器所做的那樣），所以在實際使用它之前，你不能警告使用某些東西。我不認爲用一堆消息向腳本用戶發送垃圾郵件是個好主意「警告：此腳本的開發人員正在使用已棄用的API」。

更新：但您可以創建裝飾器，將原始功能轉換爲另一個。新功能將標記/檢查開關，告訴該功能已被調用，並且僅在將開關轉入開啓狀態時纔會顯示消息。並且/或者在退出時它可以打印在程序中使用的所有被棄用功能的列表。

Answer 2

這裏的一些片段中，從那些通過引用萊安德羅改性：

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 

因爲在一些口譯露出的第一溶液（不帶過濾器處理）可能會導致警告抑制。

Answer 3

這裏是另一種解決方案：

這個裝飾（實際上是一個decorator factory）允許你給一個原因消息。通過給出源文件名和行號碼來幫助開發人員診斷問題也更加有用。

編輯：此代碼使用零的建議：它取代由warnings.warn(msg, category=DeprecationWarning, stacklevel=2)warnings.warn_explicit線， 其打印函數調用的位置，而不是函數定義的網站。它使調試更容易。

EDIT2：該版本允許開發者指定可選的「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))) 

你可以使用這個裝飾爲功能，方法和類。

下面是一個簡單的例子：

@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() 

您將獲得：

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：這個裝飾現在是過時的庫的一部分：

• Python package index (PyPi)
• GitHub website
• Read The Docs
• EBook on Lulu.com

Answer 4

更新：我覺得比較好，當我們表現出DeprecationWarning只有第一次每一行代碼，當我們可以發送一些信息：

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() 

結果：

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 

我們只需點擊警告路徑並進入PyCharm中的行。

Answer 5

您可以創建一個文件utils的

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 

，然後導入已過時的裝飾如下：

from .utils import deprecated 

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