Function environment curiosity

[Rob Hoelz <rob@...>]

Hello Lua users,

I thought I understood function environments, but I wrote a small piece
of code that has me guessing.  Here's the code:

local p = print

setfenv(0, setmetatable({}, {__index = _G, __newindex = function(_, k,
v) p 'uh-oh'
end}))

print 'still here'
print = nil 
io.write('print: ' .. tostring(print) .. '\n')

I thought that this would print the following when run:

still here
uh-oh
print: nil

but instead, it printed:

still here
print: nil

Also of note is that if I put this in a file and require that file,
global assignments cause 'uh-oh' to be printed, as I intended.  Also,
getfenv(0).print = nil triggers __newindex, as expected.

I thought that GETGLOBAL/SETGLOBAL was equivalent to operating on
getfenv(0); I checked the output of luac -l and it is using
SETGLOBAL.  What do I have wrong?

Thanks for the help,
Rob Hoelz

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