The reason C++ doesn't have reflection is that this would require the compilers to add symbol information to the object files, like what members a class type has, information about the members, about the functions and everything. This essentially would render include files useless, as information shipped by declarations would then be read from those object files (modules then). In C++, a type definition can occur multiple times in a program by including the respective headers (provided that all those definitions are the same), so it would have to be decided where to put the information about that type, just as to name one complication here. The aggressive optimization done by a C++ compiler, which can optimize out dozens of class template instantiations, is another strong point. It's possible, but as C++ is compatible to C, this would become an awkward combination.

在c++中使用反射的情况有很多，而使用模板元编程等编译时结构无法充分解决这些问题。

N3340建议用富指针作为c++中引入反射的一种方式。除此之外，它还解决了一个问题，那就是除非你使用某个功能，否则就不用为它付费。

Reflection requires some metadata about types to be stored somewhere that can be queried. Since C++ compiles to native machine code and undergoes heavy changes due to optimization, high level view of the application is pretty much lost in the process of compilation, consequently, it won't be possible to query them at run time. Java and .NET use a very high level representation in the binary code for virtual machines making this level of reflection possible. In some C++ implementations, however, there is something called Run Time Type Information (RTTI) which can be considered a stripped down version of reflection.

c++是一种不需要反射的语言，因为c++是一种可以用来编写具有反射的语言的语言。

反射可以是可选的，就像预处理器指令一样。类似的

#pragma启用反射

通过这种方式，我们可以两全其美，没有这个pragma库就可以在没有反射的情况下创建(没有任何开销)，然后就由个人开发人员决定他们想要的是速度还是易用性。

我相信，如果c++要用作数据库访问、Web会话处理/http和GUI开发的语言，那么c++中的反射是至关重要的。缺乏反射阻碍了orm(如Hibernate或LINQ)、实例化类的XML和JSON解析器、数据序列化和许多其他东西(最初必须使用无类型数据来创建类的实例)。

可以使用软件开发人员在构建过程中可用的编译时开关 为了消除这种“一分钱一分货”的顾虑。

我是一个固件开发人员，不需要反射来从串口读取数据——那么很好，不使用交换机。但是作为一个想要继续使用c++的数据库开发人员，我经常要面对一个可怕的、难以维护的代码，这些代码在数据成员和数据库结构之间映射数据。

无论是Boost序列化还是其他机制都不能真正解决反射问题——它必须由编译器来完成——一旦完成，c++将再次在学校中教授，并用于处理数据处理的软件中

对我来说，这是问题#1(而原生线程原语是问题#2)。