Re: [boost] Proposal: statefull objects

From: Bjarne Stroustrup (bs_at_[hidden])
Date: 2001-07-19 15:14:01

"Fernando Cacciola" <fcacciola_at_[hidden]> writes:
> 
> In order to introduce this proposal let's consider the following situations:
> 
> CASE A:
> =======
> 
> struct image
> {
>   ...
>   int get_pixel( int x, int y) const ;
>   ...
> } ;
> 
> How should we deal with the case of x,y being outside the image?
> Unfortunately, it might be the case that every possible integer value is a
> valid pixel color, so no value can be used to signal that there is no pixel
> at that position.
> Assume that the function should not throw an exception. 

Why/when is that a good assumption?

When used systematically, the "stateful" technique simulates on of the 
techniques for implementing simple exceptions.

        - Bjarne
Bjarne Stroustrup, http://www.research.att.com/~bs