如果你真的想了解c++的设计决策，可以找一本Ellis和Stroustrup写的《c++注释参考手册》。它并不是最新的标准，但它贯穿了最初的标准，并解释了事情是如何工作的，以及它们是如何实现的。

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.

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.

如果你真的想了解c++的设计决策，可以找一本Ellis和Stroustrup写的《c++注释参考手册》。它并不是最新的标准，但它贯穿了最初的标准，并解释了事情是如何工作的，以及它们是如何实现的。

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。

所有的语言都不应该试图融合其他语言的所有特征。

c++本质上是一个非常非常复杂的宏汇编器。它不是(传统意义上的)c#、Java、Objective-C、Smalltalk等高级语言。

对于不同的工作有不同的工具是很好的。如果我们只有锤子，所有东西看起来都像钉子。拥有脚本语言对于某些作业是有用的，而具有反射性的oo语言(Java, Obj-C, c#)对于另一类作业是有用的，而超级高效的基本的接近机器的语言对于另一类作业是有用的(c++， C, Assembler)。

C++ does an amazing job of extending Assembler technology to incredible levels of complexity management, and abstractions to make programming larger, more complex tasks vastly more possible for human beings. But it is not necessarily a language that is the best suited for those who are approaching their problem from a strictly high-level perspective (Lisp, Smalltalk, Java, C#). If you need a language with those features to best implement a solution to your problems, then thank those who've created such languages for all of us to use!

但c++是为那些出于某种原因，需要在代码和底层机器操作之间建立强相关性的人准备的。无论是它的效率，还是编程设备驱动程序，还是与底层操作系统服务的交互，或者其他什么，c++都更适合这些任务。

C#, Java, Objective-C all require a much larger, richer runtime system to support their execution. That runtime has to be delivered to the system in question - preinstalled to support the operation of your software. And that layer has to be maintained for various target systems, customized by SOME OTHER LANGUAGE to make it work on that platform. And that middle layer - that adaptive layer between the host OS and the your code - the runtime, is almost always written in a language like C or C++ where efficiency is #1, where understanding predictably the exact interaction between software and hardware can be well understood, and manipulated to maximum gain.

我喜欢Smalltalk、Objective-C，以及拥有一个包含反射、元数据、垃圾收集等的丰富运行时系统。可以编写令人惊叹的代码来利用这些设施!但这只是堆栈上的一个更高的层，它必须依赖于更低的层，而这些层最终必须依赖于操作系统和硬件。我们总是需要一种最适合构建这一层的语言:c++ /C/Assembler。

Addendum: C++11/14 are continuing to expand C++ ability to support higher-level abstractions and systems. Threading, synchronization, precise memory models, more precise abstract machine definitions are enabling C++ developers to achieve many of the high-level abstractions that some of these high-level only languages used to have exclusive domain over, while continuing to provide close-to-metal performance and excellent predictability (i.e minimal runtime subsystems). Perhaps reflection facilities will be selectively enabled in a future revision of C++, for those who want it - or perhaps a library will provide such runtime services (maybe there is one now, or the beginnings of one in boost?).