opDispatch, duck typing, and error messages

[bearophile]

Adam D. Ruppe:

> c) Maybe Phobos could help out somehow? Another thing to!()
> annoys the living crap of me with is it's runtime errors. It, again,
> doesn't tell me where in my code the problem occurred.
> 
> Perhaps have it take default __FILE__ and __LINE__ args to print out
> too? I think this can help both compile and runtime errors.

This is a more general problem of runtime errors, not just of to!(). Maybe exceptions nature should be changed a little so they store __FILE__ and __LINE__ on default (exceptions without this information are kept on request, for optimization purposes).

Bye,
bearophile