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ESO Lua File v100019

libraries/utility/baseobject.lua

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ZO_Object = {}
function ZO_Object:New(template)
    --
    -- The new instance of the object needs an index table.
    -- This next statement prefers to use "template" as the
    -- index table, but will fall back to self.
    -- Without the proper index table, your new object will
    -- not have the proper behavior.
    --
    template = template or self
    
    --
    -- This call to setmetatable does 3 things:
    -- 1. Makes a new table.
    -- 2. Sets its metatable to the "index" table
    -- 3. Returns that table.
    --
    local newObject = setmetatable ({}, template)
    
    --
    -- Obtain the metatable of the newly instantiated table.
    -- Make sure that if the user attempts to access newObject[key]
    -- and newObject[key] is nil, that it will actually fall
    -- back to looking up template[key]...and so on, because template
    -- should also have a metatable with the correct __index metamethod.
    --
    local mt = getmetatable (newObject)
    mt.__index = template
    
    return newObject
end
function ZO_Object:Subclass()
    --
    -- This is just a convenience function/semantic extension
    -- so that objects which need to inherit from a base object
    -- use a clearer function name to describe what they are doing.
    --
    return setmetatable({}, {__index = self})
end
function ZO_Object.MultiSubclass(...)
    local parentClasses = {...}
    return setmetatable({}, 
    {
        __index = function(table, key)
            for _, parentClassTable in ipairs(parentClasses) do
                local value = parentClassTable[key]
                if value ~= nil then
                    return value
                end
            end
        end
    })
end
--[[
Here is a simple multiple inheritence example:
local A = ZO_Object:Subclass()
function A:InitializeA()
self.name = "A"
end
local B = ZO_Object:Subclass()
function B:InitializeB()
self.text = "B"
end
C = ZO_Object.MultiSubclass(A, B)
function C:New()
local obj = ZO_Object.New(self)
obj:Initialize()
return obj
end
function C:Initialize()
self:InitializeA()
self:InitializeB()
end
]]
--