Python: User defined exceptions

You can create custom exceptions by extending the class Exception.

test.py

class PasswordException(Exception):
 def __init__(self, value):
  self.value = value

 def __str__(self):
  return repr(self.value) 

password=input("Enter password\n")

if(len(password) < 8):
 raise PasswordException("Minimum password lenght should be 8 characters")

$ python3 test.py 
Enter password
abcde
Traceback (most recent call last):
  File "test.py", line 11, in <module>
    raise PasswordException("Minimum password lenght should be 8 characters")
__main__.PasswordException: 'Minimum password lenght should be 8 characters'

In this example, the default __init__() of Exception has been overridden. The new behaviour simply creates the value attribute. This replaces the default behaviour of creating the args attribute.

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