-{ extension 'xglobal' }

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print "1) declare unassigned globals"
global a, b

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print "2) declare-and-assign global"
global c = 3

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print "3) assign to pre-declared globals"
a, b = 1, 2

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print "4) fail when setting an undeclared global"
local st1, msg1 = pcall(function()
   a = 4
   d = 5 -- failure, assignment to undeclared global
end)
assert(not st1)
printf ("   -> This error was expected: %s", msg1)

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print "5) fail when reading an undeclared global"
local st2, msg2 = pcall(function()
   b = c -- OK
   local _ = d -- failure, try to read undeclared global
end)
assert(not st2)
printf ("   -> This error was expected: %s", msg2)

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print "6) check the globals' values"
assert(a==4)
assert(b==3)
assert(c==3)

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print "*) done."