如何在Python的Try/Catch块中捕获所有异常？

Question

如何在Python的Try/Catch块中捕获所有异常？

pythonpython-3.xpython-2.7exceptionsubprocess

8

我正在编写Python代码，在Linux环境中安装程序所需的所有库包。因此，Linux可能包含Python 2.7或2.6或两者都有，所以我开发了一个try和except块的代码，用于在Linux上安装pip包。Try块代码包含Python 2.7版本的pip install，Catch块包含Python 2.6版本的pip install。我的问题是，当我尝试在Python 2.6中安装pandas时，它会给我带来一些错误。我想捕获该异常。请告诉我如何改进我的try except块以捕获该异常。

required_libraries = ['pytz','requests','pandas']
try:
   from subprocess import check_output
   pip27_path = subprocess.check_output(['sudo','find','/','-name','pip2.7'])
   lib_installs = [subprocess.call((['sudo',pip27_path.replace('\n',''),'install', i])) for i in required_libraries]
except:
   p = subprocess.Popen(['sudo','find','/','-name','pip2.6'], stdout=subprocess.PIPE);pip26_path, err = p.communicate()
   lib_installs = [subprocess.call((['sudo',pip26_path.replace('\n',''),'install', i])) for i in required_libraries]

- Rahul

在你已经有的 except 块中再放一个 try: except: 块？ - Chris Charles

@ChrisCharles 刚刚我尝试了相同的方法，仍然无法捕获异常。 - Rahul

@ChrisCharles 除非：尝试： p = subprocess.Popen(['sudo','find','/','-name','pip2.6'], stdout=subprocess.PIPE);pip26_path, err = p.communicate() lib_installs = [subprocess.call((['sudo',pip26_path.replace('\n',''),'install', i])) for i in required_libraries] except Exception as e: logging.info("pip_installs函数中出现错误 '%s'" %e) - Rahul

1

捕获所有异常通常是一个糟糕的想法。请参见https://dev59.com/kWkv5IYBdhLWcg3wbgbQ - tripleee

1个回答

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- mrhallak · Accepted Answer

您可以使用一个代码块捕获多个异常。让我们使用Exception和ArithmeticError来处理异常。

try:
    # Do something
    print(q)

# Catch exceptions  
except (Exception, ArithmeticError) as e:
    template = "An exception of type {0} occurred. Arguments:\n{1!r}"
    message = template.format(type(e).__name__, e.args)
    print (message)

如果需要捕获多个异常并对每个异常单独处理，则需要为每个异常编写一个except语句。

try:
    # Do something
    print(q)

# Catch exceptions  
except Exception as e:
    print (1)

except ArithmeticError as e:
    print (2)

# Code to be executed if the try clause succeeded with no errors or no return/continue/break statement

else:
    print (3)

您还可以使用if语句检查异常是否属于特定类型，例如“MyCustomException”类型。

if isinstance(e, MyCustomException):
    # Do something
    print(1)

针对您的问题，我建议将代码拆分成两个函数。

install(required_libraries)

def install(required_libraries, version='pip2.7'):
    # Perform installation
    try:
        from subprocess import check_output
        pip27_path = subprocess.check_output(['sudo','find','/','-name', version])
        lib_installs = [subprocess.call((['sudo',pip27_path.replace('\n',''),'install', i])) for i in required_libraries]

    except Exception as e:
        backup(required_libraries)

def backup(required_libraries, version='pip2.6'):
    try:
        p = subprocess.Popen(['sudo','find','/','-name',version]], stdout=subprocess.PIPE);pip26_path, err = p.communicate()
        lib_installs = [subprocess.call((['sudo',pip26_path.replace('\n',''),'install', i])) for i in required_libraries]

    except Exception as e:
        template = "An exception of type {0} occurred. Arguments:\n{1!r}"
        message = template.format(type(e).__name__, e.args)
        print (message)

        #Handle exception

注意：我没有测试过这个，而且我也不是专家，所以希望我能帮到你。

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