DiscriminatedUnions意为可识别的union，一个union变量知道自己是什么类型，或者说怎么去解释这片存储空间，std::variant即为C++17引入的类型安全的union类型，本文主解析std::variant的两种实现方式；内存如果借助tuple来实现：template<typename...Types>classVariant{public:

Considerthisdiscriminatedunioncalled Fruit:typeFruit=|{name:"apple";color:"red";}|{name:"banana";color:"ye

Wehaveatype Route thatisadiscriminatedunionofthepossibleroutesintheapplication.Eachroutehastheproperties search and routetypeRoute=

Giveadiscriminatedunion:exporttypeEvent=|{type:"click";event:MouseEvent;}|{type:"focus";event:FocusEvent;

importReact,{useState}from"react";typeBase={id:string}|string;typeGenericSelectProps<TValue>={formatLabel:(value:TValue)=>string;