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Line 1: − + − + − -- Class definition system − local derived = {}+ − local derivedMT = {+ − __index = prototype,+ − __call = function(proto, ...)+ − local instance = {}+ − local instanceMT = {+ − __index = derived,+ − __call = function()+ − return nil, "attempt to invoke an instance of a class"+ − end,+ − }+ − setmetatable(instance, instanceMT)+ − if instance.init then+ − instance:init(...)+ − end+ − return instance+ − end,+ − }+ − setmetatable(derived, derivedMT)+ − return derived+ − + +
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A complete tutorial about classes is written here: http://www.inspired-lua.org/2011/05/5-object-classes/
A complete tutorial about classes is written here: http://inspired-lua.org/index.php/2011/05/5-object-classes/
Here's how the class() function is defined, in the API :
Here's how the class([parent]) function is defined, in the API :
<source lang="lua">
<source lang="lua">
class = function(prototype)
class = function(prototype)
local derived={}
if prototype then
function derived.__index(t,key)
return rawget(derived,key) or prototype[key]
end
else
function derived.__index(t,key)
return rawget(derived,key)
end
end
function derived.__call(proto,...)
local instance={}
setmetatable(instance,proto)
local init=instance.init
if init then
init(instance,...)
end
return instance
end
setmetatable(derived,derived)
end
return derived
end
</source>
</source>
