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On Aug 5, 2005, at 3:14:14, Mike Pall wrote:

Python has a fairly elaborate scheme with forwards and backwards
compatibility, deprecation warnings and 'from __future__ import'
and whatnot. Well, you may ask ... what's wrong with it?
Well, there's a chicken-and-egg problem with this one. The parser
bails out before you can run the chunk to tell the parser that
it shouldn't (and a global flag doesn't cut it).

Doesn't Lua effectively do weak-linking? I.e. couldn't one just compare the function name against NIL? An undeclared global in Lua is NIL, after all. So, if you're running a pre-compatibility-check version of Lua, you have compatmode5_0 being NIL. Otherwise, you can call it to actually query the particular feature, can't you?

-- M. Uli Kusterer