首页 \ 问答 \ Mapstruct：将多个源对象映射到子对象(Mapstruct: Mapping multiple source objects to subobjects)

Mapstruct：将多个源对象映射到子对象(Mapstruct: Mapping multiple source objects to subobjects)

 给出一组四个对象，如：  
A{String one, B b}

B{String two, String three}

C{String one, String two}

D{String three}
 
 我希望生成如下映射：  
A cAndDToA(C c , D d);
 
 我目前无法找到一种方法来填充A中的B对象与来自C和D的数据。  
 有没有人知道这个问题的解决方案，或者有更好的方法？ 

Given a set of four objects like: 
A{String one, B b}

B{String two, String three}

C{String one, String two}

D{String three}
 
I wish to generate a mapping like: 
A cAndDToA(C c , D d);
 
I cannot currently find a way to populate the B object inside of A with data from both C and D. 
Does anyone know a solution to this issue, or have a better approach?

原文：https://stackoverflow.com/questions/35706928

更新时间：2023-06-25 19:06

最满意答案

 此检查由gcc编译器处理，特别是对于scanf / printf函数。  
 这是一个常见错误，值得为编译器添加特殊案例代码以实现这些功能。  
 请参阅GCC -WFormat标志： http ：//gcc.gnu.org/onlinedocs/gcc-3.4.4/gcc/Warning-Options.html  
 
  -Wformat：检查对printf和scanf等的调用，以确保提供的参数具有适合指定格式字符串的类型，并且格式字符串中指定的转换是有意义的。 这包括标准函数，以及printf，scanf，strftime和strfmon（X / Open扩展，而不是C标准）系列中格式属性（参见函数属性）指定的其他函数。  
 
 所有编译器都没有实现这些检查，因此肯定不能依赖它们。  
 使用GCC，您可以使用函数属性 'format'和'format-arg'告诉编译器对您的函数应用相同的检查。  
 
  format（archetype，string-index，first-to-check）format属性指定函数采用printf，scanf，strftime或strfmon样式参数，这些参数应根据格式字符串进行类型检查。 例如，声明：  
 
extern int my_printf (void *my_object, const char *my_format, ...)  
 __attribute__ ((format (printf, 2, 3)));
 
 
  ...导致编译器检查对my_printf的调用中的参数，以便与printf样式格式字符串参数my_format保持一致。  

This check is handled by the gcc compiler, specifically for scanf/printf functions. 
It's such a common error that it's worth adding special case code to the compiler for these functions. 
see the GCC -WFormat flag here: http://gcc.gnu.org/onlinedocs/gcc-3.4.4/gcc/Warning-Options.html 
 
 -Wformat : Check calls to printf and scanf, etc., to make sure that the arguments supplied have types appropriate to the format string specified, and that the conversions specified in the format string make sense. This includes standard functions, and others specified by format attributes (see Function Attributes), in the printf, scanf, strftime and strfmon (an X/Open extension, not in the C standard) families. 
 
These checks are not implemented by all compilers, so it's certainly not something to rely on. 
With GCC you can use Function Attributes 'format' and 'format-arg' to tell the compiler to apply the same checks to your functions. 
 
 format (archetype, string-index, first-to-check) The format attribute specifies that a function takes printf, scanf, strftime or strfmon style arguments which should be type-checked against a format string. For example, the declaration: 
 
extern int my_printf (void *my_object, const char *my_format, ...)  
 __attribute__ ((format (printf, 2, 3)));
 
 
 ...causes the compiler to check the arguments in calls to my_printf for consistency with the printf style format string argument my_format.

Mapstruct：将多个源对象映射到子对象(Mapstruct: Mapping multiple source objects to subobjects)

最满意答案

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