I must be missing something, but why can't you just do this with a metatable and skip the syntactic sugar altogether?
Well, the thought is that a specialized syntax could provide a useful degree of fine grain control. Whether or not to throw an error in response to an undefined reference isn't necessarily a natural a property of tables.
In some ways a '!.' syntax feels like the natural inverse of the "safe navigation" sugar I posted a few weeks back. In situations where silently returning nil is desirable, you can write:
a=node?.parent?.name
But if the situation recommends loud failures, you'd write:
a=node.parent!.name
In both cases, the error handling behavior is specified by the syntax of the call, rather than being stored as a trait of node.parent or the nil metatable.
But while the safe navigation patch is certainly one that I like, I'm not yet convinced that it's inverse is really worth the trouble. In a moment of procrastination, I went ahead and wrote the feature into my own parser -- now I'll live with it for a few months and see if it proves useful in practice.
-Sven
