Hi everyone,
From what I've seen so far I like most of the changes in Lua 5.2.0 but
there's one thing I cannot wrap my mind around. It looks like getfenv()
and setfenv() are being moved to the debug library (in other words
deprecated) while the supposed replacement really isn't...
Several of the modules I've written use setfenv() and though each of
those modules contains just a single call to setfenv() the functionality
of the whole module depends on that setfenv() call. Apart from that, if
my understanding is correct then the supposed replacement is really just
a simple syntactical wrapper for the following functionality:
local scope = {}
setfenv(function()
foo = 1
bar = 2
end, scope)()
assert(foo == nil)
assert(bar == nil)
assert(scope.foo == 1)
assert(scope.bar == 2)
This is obviously already possible in Lua 5.1, but more importantly it
is one very narrow use-case of setfenv(). I've grown to appreciate
setfenv() as core Lua functionality and now it is being deprecated
without a replacement...
Finally I'm getting to my point: I'm wondering what made the Lua authors
decide to remove setfenv() and replace it with a very narrow subset of
its functionality?! Of course I'm hoping that I misunderstood the
replacement or can change the Lua authors' minds about it, but if
neither of those is an option than I'll settle for a clear understanding
of the decision making process :-)
- Peter Odding
