How can I define a custom exception class that will only print 'Operation Cancelled' on Ke-CodePudding

Is there any way I can declare a custom exception class where I don't need to use try and run or decorators over and over? where it can catch errors itself just like the built-in KeyboardInterrupt class. Example:

def keyboard_err(func):
    def checking(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except KeyboardInter forrupt:
            pass
    return checking


class site():
    def __init__(self, link: str):
        self.link = link

    @keyboard_err
    def search(self): ...

    @keyboard_err
    def check_url(self): ...

    @keyboard_err
    def site_info(self, name: bool = False): ...

    @keyboard_err
    def write_url(self, url, type='w'): ...

    @keyboard_err
    def parse(self): ...


@keyboard_err
def custom_command(com): ...


@keyboard_err
def exclude_command(com): ...

Edit: Instead of adding the decorator again and again Can I just use a custom exception that will return a custom message by itself when the KeyboardInterrupt exception raised

CodePudding user response：

You can define your own exceptions by inheriting from the builtin Exception class:

>>> class MyCustomException(Exception):
...     pass
...

Which will have behaved in the same way as the base exception class. I.e. can be raised, try/catched, produces tracebacks and results in a sysexit with status 1:

>>> raise MyCustomException
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
__main__.MyCustomException

And:

>>> try:
...     raise MyCustomException
... except MyCustomException:
...     print('An error occured')
... 
An error occured

On your example. Is there any good reason why you want to catch KeyboardInterrupt everywhere?

CodePudding user response：

You wrote half the code. And as Michal Racko said, just creating a custom exception would help.

import sys

# To remove tracebacks. If you want them, then comment this line.
sys.tracebacklimit = 0

# Custom Exception Class
class OperationFailed(Exception):
    def __init__(self, message: object):
        self.message = message
        super().__init__(self.message)

def keyboard_err(func):
    def checking(*args, **kwargs):
        print("in decorator")
        try:
            return func(*args, **kwargs)
        except KeyboardInterrupt:
            raise OperationFailed("You have cancelled the operation") from None
        except Exception as e:
            print(e)
    return checking