Using dlsym in c++ without extern "C"

Question

I have a system in which I give the user a function prototype and the user has to implement it. Now, I compile this file using g++ and load it dynamically using dlopen and dlsym to process it further. Now, I read here: c++ dlopen mini-howto that to load c++ functions we have to use extern "C" before the function. Now, the problem is, I do not want to show the user how things are working. I do not want to show the user extern "C" before the function. Is there any way to avoid it?

Accepted Answer

You can use the mangled C++ name directly.

If you have e.g. a C++ function `void my_plugin(int foo)` , the C++ compiler will mangle that name. Once you know the mangled function name, you can use dlopen() on that name.

e.g.

```
# nm libmyplugin.so |grep my_plugin
00000000 T _Z9my_plugini
```

So here our function is named _Z9my_plugini , and you could do

```
 func = dlsym(handle, "_Z9my_plugini");
```

Traditionally different compilers could mangle the name in different ways, so this could be quite fragile, thoug these days most C++ compilers will aggree opon a standard way of mangling the names on a given platform.

However your users will be programmers, and they would normally have an understanding of exposing an entry to a dynamically loaded library as `extern "C"`

Using dlsym in c++ without extern "C"

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