Question

lua 怎么处理两个闭包公用同一个upvalue

Answer 1

作者：尼古拉斯奇凯
链接：http://www.zhihu.com/question/26159172/answer/32385871
来源：知乎
著作权归作者所有，转载请联系作者获得授权。

function C1()
local a = 1
return function ( )
a = a+1
return a
end
end

local c = C1()

function copy_with_upv(func)
local func2 = func
local up_func2 = 1
function func2()
local _,orig = debug.getupvalue(func, 1)
debug.setupvalue(func, 1, up_func2)
local result = func()
_,up_func2 = debug.getupvalue(func, 1)
debug.setupvalue(func, 1, orig)
return result
end
return func2
end

local d = copy_with_upv(c)
local e = copy_with_upv(c)
print(c())
print(d())
print(e())
print(c())
print(d())
print(e())