Lua 使表可调用
示例
有一个称为的元方法__call，它定义了对象用作功能时的行为，例如object()。这可以用来创建函数对象：
-- create the metatable with a __call metamethod
local meta = {
__call = function(self)
self.i=self.i+ 1
end,
-- to view the results
__tostring = function(self)
return tostring(self.i)
end
}
function new_counter(start)
local self = { i = start }
setmetatable(self, meta)
return self
end
-- create a counter
local c = new_counter(1)
print(c) --> 1
-- call -> count up
c()
print(c) --> 2元方法与相应的对象一起调用，所有其余参数在此之后传递给函数：
local meta = {
__call = function(self, ...)
print(self.prepend, ...)
end
}
local self = { prepend = "printer:" }
setmetatable(self, meta)
self("foo", "bar", "baz")