Re: [boost] Exception library proposal update

From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2006-07-08 04:16:56

> Why return a pointer? How about considering the use of a reference
> instead?

If you catch( foo & ), it is not guaranteed that it has an exception_info 
sub-object. For one thing, you may be converting existing code to the 
exception library, and there could be some throw foo() statements left 
around.

But also, consider catching one of the standard exception types, for example 
std::length_error. It could have been thrown by the standard library and in 
that case it would not have exception_info sub-object; or, some other code 
could throw failed<std::length_error>(), and then there would be an 
exception_info sub-object.

So, get_exception_info returns a pointer because it is intended to be used 
like this:

catch( my_error & x )
{
    if( exception_info * xi = get_exception_info(x) )
    {
        //use exception_info here
    }
    else
    {
        //handle the case of not having exception_info.
    }
}

--Emil