python - 在所有文件的打印功能上应用功能装饰器而无需导入和/或重新应用？

Question

编辑:我第一次尝试问这个问题可能有点不专心/措辞不当这里是对我正在尝试做的事情的更好解释:

我正在尝试为运行 python 的整个环境修改打印函数的默认行为，而不必修改正在运行的每个文件。

我正在尝试修饰打印功能(我知道有很多方法可以做到这一点，例如覆盖它，但这并不是我真正要问的问题)所以我可以让它打印出一些调试信息并强制执行它总是冲洗。我是这样做的:

def modify_print(func):
    # I made this so that output always gets flushed as it won't by default
    # within the environment I'm using, I also wanted it to print out some
    # debugging information, doesn't really matter much in the context of this
    # question
    def modified_print(*args,**kwargs):
        return func(f"some debug prefix: ",flush=True,*args,**kwargs)
    return modified_print

print = modify_print(print)
print("Hello world") # Prints "some debug prefix Hello World"

但是我想做的是在我的整个应用程序中修改此行为。我知道我可以在每个文件中手动装饰/覆盖/导入打印函数，但是我想知道是否有某种方法可以全局配置我的 python 环境以在任何地方装饰这个函数。我能想到的唯一方法是编辑 python 源代码并构建修改后的版本。

编辑:这是我想要实现的行为，谢谢 Match 的帮助。它会在您在 python 环境中调用打印函数的任何地方打印出行号和文件名。这意味着您不必在所有文件中手动导入或覆盖任何内容。

https://gist.github.com/MichaelScript/444cbe5b74dce2c01a151d60b714ac3a

import site
import os
import pathlib
# Big thanks to Match on StackOverflow for helping me with this
# see https://stackoverflow.com/a/48713998/5614280

# This is some cool hackery to overwrite the default functionality of
# the builtin print function within your entire python environment
# to display the file name and the line number as well as always flush 
# the output. It works by creating a custom user script and placing it 
# within the user's sitepackages file and then overwriting the builtin.

# You can disable this behavior by running python with the '-s' flag.


# We could probably swap this out by reading the text from a python file
# which would make it easier to maintain larger modifications to builtins
# or a set of files to make this more portable or to modify the behavior
# of more builtins for debugging purposes.
customize_script = """
from inspect import getframeinfo,stack
def debug_printer(func):
    # I made this so that output always gets flushed as it won't by default
    # within the environment I'm running it in. Also it will print the
    # file name and line number of where the print occurs
    def debug_print(*args,**kwargs):
        frame = getframeinfo(stack()[1][0])
        return func(f"{frame.filename} : {frame.lineno} ", flush=True,*args,**kwargs)
    return debug_print

__builtins__['print'] = debug_printer(print)
"""

# Creating the user site dir if it doesn't already exist and writing our
# custom behavior modifications
pathlib.Path(site.USER_SITE).mkdir(parents=True, exist_ok=True)
custom_file = os.path.join(site.USER_SITE,"usercustomize.py")
with open(custom_file,'w+') as f:
    f.write(customize_script)

Answer 1

您可以使用 site 中的 usercustomize 脚本模块来实现这样的事情。

首先，找出您的用户站点包目录在哪里:

python3 -c "import site; print(site.USER_SITE)"

/home/foo/.local/lib/python3.6/site-packages

接下来，在该目录中，创建一个名为 usercustomize.py 的脚本 - 现在只要运行 python，该脚本就会首先运行。

替换 print 的一种*方法是覆盖 __builtins__ 字典并用新方法替换它 - 类似于:

from functools import partial
old_print = __builtins__['print']

__builtins__['print'] = partial(old_print, "Debug prefix: ", flush=True)

将其放入 usercustomize.py 脚本中，您应该会看到所有 python 脚本从那时起就被覆盖了。您可以通过使用 -s 标志调用 python 来暂时禁用调用此脚本。

*(不确定这是否是正确的方法 - 可能有更好的方法 - 但重点是您可以使用 usercustomize 来交付您选择的任何方法)。