Bypass redis script sandboxing in order to force a set of variables into the global namespace. Use Case: Having a heavily-used script with a bunch initialization time processing (class building, constants tables, etc) that will always execute the exact same way regardless of the user input from ARGV and KEYS or the state of redis's data. This sc…

force-globals.lua

local function force_globals(globs)
    -- Check for metatable on _G. If no metatable exists,
    -- create one.
    local _G_mt = getmetatable(_G)
    if _G_mt == nil then
        return setmetatable(_G, {
            __index=globs
        })
    end
    
    -- Metatable exists. Check for existence of __index
    -- and either set or merge our globals into it.
    local _G_index = _G_mt.__index
    if _G_index == nil then
        _G.__index = globs
    else
        for key, value in pairs(globs) do
            _G_index[key] = value
        end
    end
    
    return _G
end

local function expensive(value)
    return value + 1
end

local MY_GLOBALS = {
    CONSTANT_CASE_A=expensive(0),
    CONSTANT_CASE_B=expensive(1),
    CONSTANT_CASE_C=expensive(2),
    CONSTANT_CASE_D=expensive(3),
    CONSTANT_CASE_E=expensive(4),
    CONSTANT_CASE_F=expensive(5),
}

force_globals(MY_GLOBALS)

return { CONSTANT_CASE_A, CONSTANT_CASE_B, CONSTANT_CASE_C }