宏 GENERATED_UCLASS_BODY() 与 GENERATED

继承自UE4引擎的类会生成一些宏代码。这此宏代码的作用就是帮助生成构造函数和相关成员函数


UCLASS()
class SECTION1_API ASUsableActor : public AActor
{
	GENERATED_BODY()
	
public:	
		
	
};


UCLASS()
class SURVIVALGAME_API ASUsableActor : public AActor
{
	GENERATED_UCLASS_BODY()
 
public:
 
	
};

F12跳转到这两个宏的声明文件中


#define GENERATED_BODY() \
PRAGMA_DISABLE_DEPRECATION_WARNINGS \
public: \
	ASUsableActor_RPC_WRAPPERS_NO_PURE_DECLS \
	ASUsableActor_CALLBACK_WRAPPERS \
	ASUsableActor_INCLASS_NO_PURE_DECLS \
	ASUsableActor_ENHANCED_CONSTRUCTORS \
private: \
PRAGMA_POP

GENERATED_BODY() 会经过一系列的宏替换最下边成员访问方式为 private: 也就是说紧随 GENERATED_BODY()之后而又没有显著更改成员访问方式，那么访问方式则为private


#define GENERATED_UCLASS_BODY() \
PRAGMA_DISABLE_DEPRECATION_WARNINGS \
public: \
	ASUsableActor_RPC_WRAPPERS \
	ASUsableActor_CALLBACK_WRAPPERS \
	ASUsableActor_INCLASS \
	ASUsableActor_STANDARD_CONSTRUCTORS \
public: \
PRAGMA_POP

而GENERATED_UCLASS_BODY() 后边声名的成员变量访问方式则为公有。


#define ASUsableActor_RPC_WRAPPERS
#define ASUsableActor_CALLBACK_WRAPPERS

这两个为空宏，在C/C++ 中空宏会被空格替换大多用来表示注释

GENERATED_UCLASS_BODY() 中的两个非空宏声明如下


#define ASUsableActor_INCLASS \
	private: \
	static void StaticRegisterNativesASUsableActor(); \
	friend SECTION1_API class UClass* Z_Construct_UClass_ASUsableActor(); \
	public: \
	DECLARE_CLASS(ASUsableActor, AActor, COMPILED_IN_FLAGS(0), 0, Section1, NO_API) \
	DECLARE_SERIALIZER(ASUsableActor) \
	/** Indicates whether the class is compiled into the engine */    enum {IsIntrinsic=COMPILED_IN_INTRINSIC}; \
	UObject* _getUObject() const { return const_cast<ASUsableActor*>(this); }

这几行主要是为类声明一些成员方法


#define ASUsableActor_STANDARD_CONSTRUCTORS \
	/** Standard constructor, called after all reflected properties have been initialized */ \
	NO_API ASUsableActor(const FObjectInitializer& ObjectInitializer); \
	DEFINE_DEFAULT_OBJECT_INITIALIZER_CONSTRUCTOR_CALL(ASUsableActor) \
private: \
	/** Private copy-constructor, should never be used */ \
	NO_API ASUsableActor(const ASUsableActor& InCopy); \
public:

这里可以看到声明了一个公有构造函数和一个私有的拷贝构造函数，公有构造函数参数为FObjectInitializer的引用常量。而拷贝构造函数声明为私有，则表示拷贝构造函数不可用

下边两个是 GENERATED_BODY() 中引用的非空宏声明


#define ASUsableActor_RPC_WRAPPERS_NO_PURE_DECLS \
	static inline void StaticChecks_Implementation_Validate() \
	{ \
	}


#define ASUsableActor_INCLASS_NO_PURE_DECLS \
	private: \
	static void StaticRegisterNativesASUsableActor(); \
	friend SECTION1_API class UClass* Z_Construct_UClass_ASUsableActor(); \
	public: \
	DECLARE_CLASS(ASUsableActor, AActor, COMPILED_IN_FLAGS(0), 0, Section1, NO_API) \
	DECLARE_SERIALIZER(ASUsableActor) \
	/** Indicates whether the class is compiled into the engine */    enum {IsIntrinsic=COMPILED_IN_INTRINSIC}; \
	UObject* _getUObject() const { return const_cast<ASUsableActor*>(this); }


#define ASUsableActor_ENHANCED_CONSTRUCTORS \
private: \
	/** Private copy-constructor, should never be used */ \
	NO_API ASUsableActor(const ASUsableActor& InCopy); \
public: \
	DEFINE_DEFAULT_CONSTRUCTOR_CALL(ASUsableActor)