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----
-- a basic class mechanism.
-- Used for some of the demonstrations; the `class` macro in the `module`
-- package uses it. It provides a single function which returns a new 'class'.
-- The resulting object can be called to generate an instance of the class.
-- You may provide a base class for single inheritance; in this case, the functions
-- of the base class will be copied into the new class' metatable (so-called 'fat metatable')
--
-- Example:
--
-- local class = require 'macro.lib.class'
-- A = class()
-- function A._init(name) self.name = name end
-- a = A("hello")
-- assert(a.name == "hello")
--
-- @module macro.lib.class
return function (base)
-- OOP with single inheritance
local klass,cmt = {},{}
if base then -- 'fat metatable' inheritance
for k,v in pairs(base) do klass[k] = v end
end
klass.__index = klass
-- provide a callable constructor that invokes user-supplied ctor
function cmt:__call(...)
local obj = setmetatable({},klass)
if klass._init then klass._init(obj,...)
elseif base and base._init then base._init(base,...) end
return obj
end
setmetatable(klass,cmt)
return klass
end
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