UE4 GENERATED宏

参考博客:https://blog.csdn.net/cartzhang/article/details/72834164

在引擎中的定义:

// This pair of macros is used to help implement GENERATED_BODY() and GENERATED_USTRUCT_BODY()
#define BODY_MACRO_COMBINE_INNER(A,B,C,D) A##B##C##D
#define BODY_MACRO_COMBINE(A,B,C,D) BODY_MACRO_COMBINE_INNER(A,B,C,D)

// Include a redundant semicolon at the end of the generated code block, so that intellisense parsers can start parsing
// a new declaration if the line number/generated code is out of date.
#define GENERATED_BODY_LEGACY(...) BODY_MACRO_COMBINE(CURRENT_FILE_ID,_,__LINE__,_GENERATED_BODY_LEGACY);
#define GENERATED_BODY(...) BODY_MACRO_COMBINE(CURRENT_FILE_ID,_,__LINE__,_GENERATED_BODY);

#define GENERATED_USTRUCT_BODY(...) GENERATED_BODY()
#define GENERATED_UCLASS_BODY(...) GENERATED_BODY_LEGACY()
#define GENERATED_UINTERFACE_BODY(...) GENERATED_BODY_LEGACY()
#define GENERATED_IINTERFACE_BODY(...) GENERATED_BODY_LEGACY()

这边的逻辑顺序是:

GENERATED_BODY ————> BODY_MACRO_COMBINE ————> BODY_MACRO_COMBINE_INNER————>A##B##C##D

##在宏里的意思是合并两个string,

那么A##B##C##D 也就是CURRENT_FILE_ID_,__LINE__,_GENERATED_BODY

经过别人博客的提示,在generated.h最后一行有

#undef CURRENT_FILE_ID
#define CURRENT_FILE_ID SVN_PROJECT_Source_FPSGame_Public_ShooterCharacter_h

其中 我猜CURRENT_FILE_ID 是原字符, SVN_PROJECT是项目目录名字, _Source_FPSGame_Public_ShooterCharacter_h是项目名字和class名字.