Re: upcoming changes in Lua 5.2 [was Re: Location of a package]

[David Given <dg@...>]

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Shmuel Zeigerman wrote:
[...]
> I think no warnings are needed. As in all other cases, it is the
> programmer's responsibility to take the scope into account. E.g., if the
> code says 'until x > 0', and x is not defined in the enclosing scope,
> it'll result in the run-time error "attempt to compare nil with number'.

Ah, but changing this now will break existing, correct code that relies
on this scoping behaviour. This is a Bad Thing. Even the Lua 5.1 -> 5.2
transition managed to keep pretty much all 5.1 code working on 5.2, with
some compatibility tweaks... but I'm not sure how this could be managed
in this case. (With a compiler flag to ask for old behaviour.)

Consider how much grief the equivalent transition caused in C++. I'm
*still* running into cases where code that does 'for (int i = ...)' does
the wrong thing on some production compilers.

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