Variable Scope Demo (Lua)

--[[
    In Lua variables declared outside of any function/procedure/loop etc are
    available to the whole script.
    you should use the local keyword on all variables declared, as this makes them LOCAL to the
    entire script (effectively global), but not available to other scripts in the project.

    They are READ/WRITE inside a function/procedure (unlike Python)

    Variables declared inside functions/procedures/loops SHOULD be local to that code block.
    This only occurs if the local keyword is used, They are deleted when the code block is ended.
    If you decare a variable inside a function WITHOUT the local keyword, it is still available to the rest
    of the script, just as if it were declared outside the function.
    This is unique to Lua.
]]
local globalDemoVariable = "Hello World" -- global to the whole of this script, not available to other scripts

function luaScopeDemo()
    print(globalDemoVariable)
    globalDemoVariable = "Goodbye" -- unlike python this variable can be changed here
    print(globalDemoVariable)

    local localDemoVariable = "this is a local string variable" -- local to this function. Deleted as soon as procedure has completed
    --localDemoVariable = "this is also a global string variable" -- no local keyword: still available after procedure has completed
    print(localDemoVariable)
end

function main()
    luaScopeDemo()
    print(localDemoVariable) -- no longer available as was local to the procedure, so nil is printed. Does NOT cause error as in C#/Python
    io.write("Enter to quit")
    io.read() -- stop console closing
end

main()