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Inheritance/Single: Difference between revisions
→{{header|Lua}}: added Lua solution
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:- end_object.</lang>
=={{header|Lua}}==
Lua has no in-built formal OOP mechanism, though there are many possible ways of implementing work-alikes.
<lang lua>Class = {
classname = "Class aka Object aka Root-Of-Tree",
new = function(s,t)
s.__index = s
local instance = setmetatable(t or {}, s)
instance.parent = s
return instance
end
}
Animal = Class:new{classname="Animal", speak=function(s) return s.voice or "("..s.classname.." has no voice)" end }
Cat = Animal:new{classname="Cat", voice="meow"}
Dog = Animal:new{classname="Dog", voice="woof"}
Lab = Dog:new{classname="Lab", voice="bark"}
Collie = Dog:new{classname="Collie"} -- subclass without a unique voice
print("Animal:speak(): " .. Animal:speak())
print("Cat:speak(): " .. Cat:speak())
print("Dog:speak(): " .. Dog:speak())
print("Lab:speak(): " .. Lab:speak())
print("Collie:speak(): " .. Collie:speak())
max = Collie:new{voice="Hi, I am Max the talking Collie!"} -- instance with a unique voice
print("max:speak(): " .. max:speak())
print("max himself is (instance): " .. max.classname)
print("max's parent is (class): " .. max.parent.classname)
print("max's parent's parent is (class): " .. max.parent.parent.classname)
print("max's parent's parent's parent is (class): " .. max.parent.parent.parent.classname)
print("max's parent's parent's parent's parent is (class): " .. max.parent.parent.parent.parent.classname)
print("max's parent's parent's parent's parent's parent is (nil reference): " .. tostring(max.parent.parent.parent.parent.parent))</lang>
{{out}}
<pre>Animal:speak(): (Animal has no voice)
Cat:speak(): meow
Dog:speak(): woof
Lab:speak(): bark
Collie:speak(): woof
max:speak(): Hi, I am Max the talking Collie!
max himself is (instance): Collie
max's parent is (class): Collie
max's parent's parent is (class): Dog
max's parent's parent's parent is (class): Animal
max's parent's parent's parent's parent is (class): Class aka Object aka Root-Of-Tree
max's parent's parent's parent's parent's parent is (nil reference): nil</pre>
=={{header|M2000 Interpreter}}==
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