User Defined Attributes

[Walter Bright]

On 11/6/2012 7:52 PM, bearophile wrote:
> Walter Bright:
>
>> But I'm not sure at this point if that is the right thing to do.
>
> Why?

D was fortunate in having 10 years of experience with C++'s exception system to 
learn from. We don't have that with UDAs.


> [If you decide to restrict UDAs, then later it will be easy to extend them, it
> will not break code. While doing the opposite break code. It's you the one that
> has taught me to design things this way :-) ]

It's a good point, but I have no experience with UDAs. There may be emergent 
behavior with these features that is completely unexpected, and we wouldn't find 
out about it without having it there.

Yes, I know it's a risk.

(And it was a no-brainer to restrict the exception types. But one must be 
careful in drawing analogies in programming, as different things are, well, 
different and can be different in unexpected, surprising ways.)