UE4的BlueprintPure用法

        /// This function fulfills a contract of producing no side effects, and additionally implies BlueprintCallable.
        BlueprintPure,

BlueprintPure：感觉BlueprintPure修饰的函数和BlueprintCallable没太大区别，在C++和蓝图都可以调用，但是BlueprintPure修饰的函数必须有函数返回值或者函数参数输出；否则编译失败： LogCompile: Error: BlueprintPure specifier is not allowed for functions with no return value and no output parameters.

    UFUNCTION(BlueprintPure)
        void TestPureFunc(int& a);//编译通过

 UFUNCTION(BlueprintPure)
        void TestPureFunc(int a);//编译失败

 UFUNCTION(BlueprintPure)
        int TestPureFunc();//编译通过

 UFUNCTION(BlueprintPure)
        void TestPureFunc();//编译失败

 UFUNCTION(BlueprintPure)
        int TestPureFunc(int a);//编译通过

 UFUNCTION(BlueprintPure)
        int TestPureFunc(int& a);//编译通过