teach your Grandma prototypical inheritance? was (Uncommon OOP in Lua: right or wrong?)

["Patrick Mc(avery" <spell_gooder_now@...>]

Just some silly enthusiast code here but I was wondering if there is 
anything terribly wrong with it other then it's global variables?

Would this scheme of prototypical inheritance be suitable for teaching 
someone who knew nothing about this topic?

Surely the meta table approach is better but this code seems pretty 
easy, perhaps easier for someone new to programming.

Thanks for reading-Patrick

mammal = {}
mammal.blood = function() print("warm") return  end

cat = {}
cat.selfDefence = function() print("claws") return  end

tabbyCat = {}
tabbyCat.color = 'orange'


function ifFails(field)
    local toSort = {
        mammal[field],
        cat[field],
        tabbyCat[field],
}

--manually enter the length of toSort as it has holes
local giveUp = 4
local i = 1

while true do
    r = toSort[i]
    if i == giveUp then print('no such field found') break end
    if r ~= nil then break end
        i = i +1
            end
    return r
end


		
d = ifFails('blood') --returns a function
e = ifFails("selfDefence") --returns a function
f = ifFails("color") --returns a string
g = ifFails("gonnaFail") --should return nil

d() -->warm
e() --> claws
print(f) -->orange
print(g) -->nil