[boost] Minor exception lib changes

From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2006-07-10 00:58:37

Hello,

I am contemplating a few minor changes to the exception library and I wanted 
to get some input before I implement them.

First, I think that the function template failed should be renamed. Somehow, 
boost::failed doesn't feel right. Since English is not native to me, I 
really need help with this one.

Second, I'm thinking of renaming wrap_string/get_string. Those names did 
make sense in the implementation I've been using in my own code, because the 
whole thing was in namespace except. Clearly, boost::get_string doesn't 
suggest that it's part of the exception library. I'm thinking of renaming 
them both to exception_string. So, stuffing a string at the time of the 
throw would look like this:

throw failed<foo>() << exception_string<tag>("value");

To extract the string from an exception_info object, you'd do this:

exception_info & xi;
if( std::string const * s = exception_string<tag>(xi) )
    ....

Similarly, it makes sense to rename both wrap_errno/get_errno to 
exception_errno.

Thanks for everyone's input!

--Emil