lua当变量作为函数的参数进行传递时,类似的也是boolean,string,number类型的变量进行值传递。而table,function,userdata类型的变量进行引用传递。故而当table进行赋值操作之时,table A
赋值给table B,对表B中元素进行操作自然也会对A产生影响,当然对B表本身进行处理例如B =nil或者将表B指向另一个表,则对A是没什么影响的;下面即是对lua table的深度拷贝。
deepcopy = function(object) local lookup_table = {} local function _copy(object) if type(object) ~= "table" then return object elseif lookup_table[object] then return lookup_table[object] end local new_table = {} lookup_table[object] = new_table for index, value in pairs(object) do new_table[_copy(index)] = _copy(value) end return setmetatable(new_table, getmetatable(object)) end return _copy(object) end local testA = {1,2,3,4,5} local testB = testA testB[2] = "我擦" local testC = deepcopy(testA) testC[2] = "我勒个去" for k , v in ipairs (testA) do print("testA",k, v ) end print("============================") for k , v in ipairs (testC) do print("testC",k, v ) end
运行结果如下:
testA 1 1
testA 2 我擦
testA 3 3
testA 4 4
testA 5 5
============================
testC 1 1
testC 2 我勒个去
testC 3 3
testC 4 4
testC 5 5