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luaSub's 'using' extension does the following:

--    local sin,cos,tan= using math
--      -->
--    local sin,cos,tan = math.sin, math.cos, math.tan

It would be trivial to make this use 'require'. The reason that variables are named on the left side is a technical one.


Alexander Gladysh kirjoitti 24.3.2008 kello 12:49:
When used frequently, however, it can be a performance win since it
eliminates a table lookup. I've started to use the convention:

   local Corge_foo =

1. I prefer to avoid using require.
2. There is no validation for to actually exist.


If you prefer, the "key not exist" function could be defined
apart from the module:

 local Corge_foo = import(Corge, 'foo')    -- or
 local Corge_foo = checked(Corge).foo

My import() function does check for the key existance. What I meant in
the original post is that there is no protection from messing up order
of existant key:

local foo, bar, baz = import 'path/to/file.lua' { 'bar', 'baz', 'foo' }

If you write it separately, well, yes, it would arguably be somewhat
easier to spot while reading code, but at price of greater code bloat:

 local file = import 'path/to/file.lua' -- Okay, set metatable there
 local foo =
 local bar =
 local baz = file.baz

As soon as you fold it in single line for compactness, all benefits vanish:

 local file = import 'path/to/file.lua'
 local foo, bar, baz =, file.baz, file.baz