当你只想做一个try-except而不处理异常时,你在Python中如何做呢?

下面的方法是正确的吗?

try:
    shutil.rmtree(path)
except:
    pass

当前回答

我通常会这样做:

try:
    doSomething()
except:
    _ = ""

其他回答

通常认为最佳实践是只捕获您感兴趣的错误。在shutil的例子中。rmtree可能是OSError:

>>> shutil.rmtree("/fake/dir")
Traceback (most recent call last):
    [...]
OSError: [Errno 2] No such file or directory: '/fake/dir'

如果你想默默地忽略这个错误,你可以这样做:

try:
    shutil.rmtree(path)
except OSError:
    pass

为什么?假设你(以某种方式)不小心给函数传递了一个整数而不是字符串,比如:

shutil.rmtree(2)

它会给出错误“TypeError: coercing to Unicode: need string or buffer, int found”——你可能不想忽略它,这可能很难调试。

如果你确实想忽略所有错误,捕获Exception而不是一个裸的except:语句。再一次,为什么?

不指定异常会捕获每个异常,包括SystemExit异常,例如sys.exit()使用:

>>> try:
...     sys.exit(1)
... except:
...     pass
... 
>>>

将其与正确退出的以下选项进行比较:

>>> try:
...     sys.exit(1)
... except Exception:
...     pass
... 
shell:~$ 

如果你想编写更好的代码,OSError异常可以表示各种错误,但在上面的例子中,我们只想忽略Errno 2,所以我们可以更具体:

import errno

try:
    shutil.rmtree(path)
except OSError as e:
    if e.errno != errno.ENOENT:
        # ignore "No such file or directory", but re-raise other errors
        raise

完整性:

>>> def divide(x, y):
...     try:
...         result = x / y
...     except ZeroDivisionError:
...         print("division by zero!")
...     else:
...         print("result is", result)
...     finally:
...         print("executing finally clause")

还要注意,你可以像这样捕获异常:

>>> try:
...     this_fails()
... except ZeroDivisionError as err:
...     print("Handling run-time error:", err)

...并像这样重新抛出异常:

>>> try:
...     raise NameError('HiThere')
... except NameError:
...     print('An exception flew by!')
...     raise

此外,多种异常类型可以作为圆括号元组来处理:

try:
    i_might_fail()
except (ValueError, TypeError) as ex:
    print('I failed with: ', ex)

...或作为单独的除条款:

try:
    i_might_fail()
except ValueError:
    print('handling a ValueError...')
except TypeError:
    print('handling a TypeError...')

...请参阅python教程。

我需要忽略多个命令和fuckit的错误

import fuckit

@fuckit
def helper():
    print('before')
    1/0
    print('after1')
    1/0
    print('after2')

helper()

在Python中,我们处理异常的方式与其他语言类似,但区别在于语法上的不同,例如,

try:
    #Your code in which exception can occur
except <here we can put in a particular exception name>:
    # We can call that exception here also, like ZeroDivisionError()
    # now your code
# We can put in a finally block also
finally:
    # Your code...

当你只想做一个try catch而不处理异常时,你在Python中如何做呢?

这取决于你对“处理”的定义。

如果你想抓住它不采取任何行动,你张贴的代码将工作。

如果你的意思是你想对一个异常采取行动,而不阻止该异常上升到堆栈,那么你想要这样的东西:

try:
    do_something()
except:
    handle_exception()
    raise  #re-raise the exact same exception that was thrown