[Date Prev][Date Next][Thread Prev][Thread Next]
- Subject: Re: Let's not break existing scripts.
- From: Duncan Cross <duncan.cross@...>
- Date: Thu, 10 Nov 2011 18:06:33 +0000
On Thu, Nov 10, 2011 at 5:58 PM, Petite Abeille
> 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.
This has been discussed before: