Question

有许多内置的异常类，如EOFError，KeyboardInterrupt等。但是我如何创建自己的异常类。例如，如果我想保持约束，用户应输入长度至少为3的字符串。

Answer 1

检查此代码是否存在用户定义的异常：

class ShortInputException(Exception):
    def __init__(self,length,atleast):
        Exception.__init__(self)
        self.length = length
        self.atleast = atleast

try:
    text = input('Enter some text: ')
    if len(text) < 3:
        raise ShortInputException(len(text),3)
except EOFError:
    print('It is end of file.')
except ShortInputException as ex:
    print('ShortInputException: You entered {0} length long text. Expected text size is {1}'.format(ex.length,ex.atleast))
except KeyboardInterrupt:
    print('You interrupted the program execution.')
else:
    print('No exception/s raised.')
    print('You entered: {0}'.format(text))

Answer 2

您可以在类中定义例外，也可以在下面创建自己的例外类。

/ ** *定义一个扩展Exception的异常类 * /

class Your_Exception扩展了Exception：

// redefine exception with a message
public function __construct($message, $code = 0, Exception $previous = null):

    //Call Parent constructor
    parent::__construct($message, $code, $previous);


// custom string representation of object
public function __to_String():
    return __CLASS__ . ": [{$this->code}]: {$this->message}\n";


public function user_defined_Function() :
    echo "user defined exception exception\n";

如何在Python中实现用户定义的异常？

2 个答案: