小寄巧

• 模板加友元访问未被UPROPERTY标记的私有成员

  //比如要访问UGameFeaturesSubsystem中的GameFeaturePluginNameToPathMap
  template<auto M>
  struct SneakTunnel;
  
  template<class T, class U, T U::*M>
  struct SneakTunnel<M> 
  {
  	friend T& Sneak_GameFeaturesSubsystem(U& u) 
      {
  		return u.*M;
  	}
  };
  
  template struct SneakTunnel<&UGameFeaturesSubsystem::GameFeaturePluginNameToPathMap>;
  TMap<FString,FString>& Sneak_GameFeaturesSubsystem(UGameFeaturesSubsystem&);
  
  //使用方法
  auto& take_control = Sneak_GameFeaturesSubsystem(*Subsystem);
  take_control.Add(PluginName,PluginURL);
  

• 2.0版本（一键失业）

  //宏定义
  #define ACCESS_MEMBER(ClassName, Member,MemberType) \
  template<auto M>\
  struct Accessor_##ClassName##Member;\
  \
  template<class T, class U, T U::*M>\
  struct Accessor_##ClassName##Member<M> {\
  friend T& Get##Member##From##ClassName(U& u) {\
  return u.*M;\
  }\
  };\
  \
  template struct Accessor_##ClassName##Member<&ClassName::Member>;\
  MemberType& Get##Member##From##ClassName(ClassName&);\
  
  
  //在项目的某个地方,我们要取出UGameInstance类的SubsystemCollection成员，它是个private 属性，它的类型是FObjectSubsystemCollection<UGameInstanceSubsystem>
  //直接写这么一行
  ACCESS_MEMBER(UGameInstance,SubsystemCollection,FObjectSubsystemCollection<UGameInstanceSubsystem>)
  //调用，这其实是UGameInstance::Init()的内容，但是我想要自定义初始化，只能这样了
  GetSubsystemCollectionFromUGameInstance(*this).Initialize(this);
  
  

接口