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On Nov 10, 2011, at 7:06 PM, Duncan Cross wrote:

> No, no and no. :)

Right, my bad :)

> _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:

Yes, thanks for the pointer, got confused somewhere along the way :))

FWIW, I use the following rendition of Sergey Rhozenko's original 5.2 setfenv:

function setfenv( aFunction, anEnvironment )
    local aFunction = GetFunction( aFunction, 2 )

    for anIndex, aName, aValue in UpValues( aFunction ) do
        if aName == '_ENV' then
            return upvaluejoin( aFunction, anIndex, function() return anEnvironment end, 1 )
    error( 'No _ENV found for ' .. aFunction )

Aside from its reliance on debug info, is there anything else subtly broken in that function?