[Tutor] Regarding Exceptions

[Alan Gauld]

On 17/02/14 11:44, Khalid Al-Ghamdi wrote:
> Why is it i can use mu custom class exception without creating an
> exception object first?

There are formatting problems when I try to copy your code.
I've tried to fix them below, apologies if I got it wrong.

However you do create an instance when you raise it...

 > class ShortInputException(Exception):
 >    def __init__(self, length, atleast):
 >        Exception.__init__(self)
 >        self.length = length
 >        self.atleast = atleast
 >try:
 >    text = input()
 >    if len(text) < 3:
 >      raise ShortInputException(len(text), 3)

You have your class name followed by parens.
That's how you create an instance.
So you are raising an instance of your class.

except ShortInputException as ex:
     print(...

And you catch the instance as ex here...

But remember that in Python classes are objects too...
So you don't always need to create an instance to
use a class.

HTH
-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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