require("import")	-- the import fn
import("smart_pointer_multi")	-- import lib into global
spm=smart_pointer_multi --alias

-- catching undefined variables
local env = _ENV -- Lua 5.2
if not env then env = getfenv () end -- Lua 5.1
setmetatable(env, {__index=function (t,i) error("undefined global variable `"..i.."'",2) end})

foo = spm.Foo()
foo.x = 5
assert( foo:getx() == 5 )

bar = spm.Bar(foo)
spam = spm.Spam(bar)
grok = spm.Grok(bar)

assert( bar:getx() == 5 )
assert( spam:getx() == 5 )
spam.x = 7
assert( grok:getx() == 7 )
grok.x = 10
assert( foo:getx() == 10 )