Lua middle__ index、__ Understanding of newindex, rawget and rawset

  All premises , Set up tab The meta table of is meta, When the found value or the assigned value does not exist , Meta table meta Go check __index perhaps __newindex Whether there is .

__index： When you need to call a function or variable that does not exist in the current table , Look up the meta table and call it .

 

rawget： Give Way __index invalid , Get the real value . The significance here lies in , Due to the existence of meta table , To get the true value, you need to use this method .

__newindex ： When you need to assign a function or variable that does not exist in the current table , Assign values to the meta table .

 

 rawset： When there is a meta table ,__newindex There is , If not used rawset Assign a value to that nonexistent value , Will be carried out in __newindex Infinite assignment of , Dead cycle .