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On 22-Sep-04, at 12:33 AM, Mark Hamburg wrote:

PiL finishes the chapter on object-oriented programming with the rather
Scheme-like approach of implementing objects as function closures. Would it make sense to define obj:msg( ... ) as meaning obj( "msg", ... ) if obj were a function? This has the downside of meaning that the syntax is no longer
simply sugar, but it had already ceased to be treated as such in the

Now that I've thought about this since the first time you suggested it, it seems more reasonable to me. I find it particularly attractive for the case where obj is a coroutine.

To answer Alex's concern (and the second part of the suggestion which I think is unworkable), the compiler does not need to know what type of object is being self-called, because it simply injects a self call opcode, which causes the VM to turn (object, method) into (object[method], object). A very simple change to that opcode would handle the case where object was a function (i.e., do nothing instead of reporting an error).

However, it does create an ambiguity in the case where object is either a table with a __call metamethod or a userdata with both __call and __index metamethods. Perhaps this is not serious: this could be dealt with by simply documenting that gettable (if it exists) takes priority, even if it fails to find the key.