如果你像这样声明一个指向函数的指针:

int (*func)(int a, int b);

您可以像这样在内存中为该函数分配一个位置(需要libdl和dlopen)

#include <dlfcn.h>

int main(void)
{
    void *handle;
    char *func_name = "bla_bla_bla";
    handle = dlopen("foo.so", RTLD_LAZY);
    *(void **)(&func) = dlsym(handle, func_name);
    return func(1,2);
}

要使用间接方式加载局部符号，可以对调用二进制文件(argv[0])使用dlopen。

这样做的唯一要求(除了dlopen()、libdl和dlfcn.h)是知道函数的参数和类型。

这些信息确实存在——但不是你需要的格式，而且只有当你导出你的类时。这适用于Windows，我不知道其他平台。使用存储类说明符，例如:

class __declspec(export) MyClass
{
public:
    void Foo(float x);
}

这使得编译器将类定义数据构建到DLL/Exe中。但它不是一种可以用于反射的格式。

在我的公司，我们建立了一个解释元数据的库，允许你在不插入额外的宏等到类本身的情况下反映一个类。它允许如下方式调用函数:

MyClass *instance_ptr=new MyClass;
GetClass("MyClass")->GetFunction("Foo")->Invoke(instance_ptr,1.331);

这有效地做到:

instance_ptr->Foo(1.331);

Invoke(this_pointer，…)函数有可变参数。显然，通过这样调用函数，你可以绕过诸如const-safety之类的东西，所以这些方面是作为运行时检查实现的。

我相信语法可以改进，到目前为止它只适用于Win32和Win64。我们发现它非常有用，可以为类提供自动GUI接口，在c++中创建属性，流到XML和从XML输出等等，而且不需要从特定的基类派生。如果有足够的需求，也许我们可以把它做成样子发布。

I did something like what you're after once, and while it's possible to get some level of reflection and access to higher-level features, the maintenance headache might not be worth it. My system was used to keep the UI classes completely separated from the business logic through delegation akin to Objective-C's concept of message passing and forwarding. The way to do it is to create some base class that is capable of mapping symbols (I used a string pool but you could do it with enums if you prefer speed and compile-time error handling over total flexibility) to function pointers (actually not pure function pointers, but something similar to what Boost has with Boost.Function--which I didn't have access to at the time). You can do the same thing for your member variables as long as you have some common base class capable of representing any value. The entire system was an unabashed ripoff of Key-Value Coding and Delegation, with a few side effects that were perhaps worth the sheer amount of time necessary to get every class that used the system to match all of its methods and members up with legal calls: 1) Any class could call any method on any other class without having to include headers or write fake base classes so the interface could be predefined for the compiler; and 2) The getters and setters of the member variables were easy to make thread-safe because changing or accessing their values was always done through 2 methods in the base class of all objects.

It also led to the possibility of doing some really weird things that otherwise aren't easy in C++. For example I could create an Array object that contained arbitrary items of any type, including itself, and create new arrays dynamically by passing a message to all array items and collecting the return values (similar to map in Lisp). Another was the implementation of key-value observing, whereby I was able to set up the UI to respond immediately to changes in the members of backend classes instead of constantly polling the data or unnecessarily redrawing the display.

也许您更感兴趣的是，您还可以转储为类定义的所有方法和成员，而且是字符串形式。

该系统的缺点可能会让您望而却步:添加所有消息和键值非常繁琐;它比没有反射要慢;你会讨厌看到boost::static_pointer_cast和boost::dynamic_pointer_cast遍布你的代码库;强类型系统的局限性仍然存在，您实际上只是将它们隐藏了一些，所以它不那么明显。字符串中的错别字也不是一个有趣或容易发现的惊喜。

As to how to implement something like this: just use shared and weak pointers to some common base (mine was very imaginatively called "Object") and derive for all the types you want to use. I'd recommend installing Boost.Function instead of doing it the way I did, which was with some custom crap and a ton of ugly macros to wrap the function pointer calls. Since everything is mapped, inspecting objects is just a matter of iterating through all of the keys. Since my classes were essentially as close to a direct ripoff of Cocoa as possible using only C++, if you want something like that then I'd suggest using the Cocoa documentation as a blueprint.

编辑:不再维护CAMP;有两个fork可供选择:

其中一个也被称为CAMP，并且基于相同的API。 思考是部分重写，应该优先考虑，因为它不需要Boost;它使用c++ 11。

CAMP是MIT授权的库(以前是LGPL)，它向c++语言添加了反射。它在编译中不需要特定的预处理步骤，但是必须手动进行绑定。

目前的Tegesoft库使用Boost，但也有一个使用c++ 11的分支不再需要Boost。

编辑:更新的坏链接截至2017年2月7日。

我想没有人提到这一点:

在CERN，他们使用c++的全反射系统:

欧洲核子研究中心的反射。看起来效果很好。

当我想要在c++中进行反射时，我读了这篇文章并改进了我在那里看到的东西。对不起，没有罐头。结果不是我的…但你当然可以得到我所拥有的，然后从那里开始。

我目前正在研究，当我喜欢的时候，使用inherit_linear的方法使可反射类型的定义更容易。实际上我已经学了很多，但还有一段路要走。c++ 0x中的变化很可能在这方面有很大的帮助。