Re: Let's not break existing scripts.

[Matthew Frazier <leafstormrush@...>]

On Nov 10, 2011, at 13:06 , Duncan Cross wrote:

> On Thu, Nov 10, 2011 at 5:58 PM, Petite Abeille
> <petite.abeille@gmail.com> wrote:
>> 
>> On Nov 10, 2011, at 6:20 PM, Peter Cawley wrote:
>> 
>>> It is also impossible to write setfenv in 5.2 in such a way as to work
>>> with bytecode chunks whose debug information has been stripped.
>> 
>> Why? _ENV is always the first upvalue, no? No need to look it up by name, no? Its position will suffice, no?
> 
> No, no and no. :)
> 
> _ENV is only the first upvalue for a function that was compiled from a
> top-level source code chunk. Functions *in general*, i.e. also
> including functions defined inside a chunk or other function, may have
> _ENV at a different position, or even not at all.

Would it be possible for the compiler to ensure that _ENV is always the first upvalue?

Thanks,
Matthew Frazier
http://leafstorm.us/