On 7/2/07, Stephan Diederich <stephan.diederich@googlemail.com> wrote:
On 6/29/07, Jeremy Pack <rostovpack@gmail.com> wrote:
On 6/29/07, Stephan Diederich <stephan.diederich@googlemail.com> wrote:
On 5/29/07, Jeremy Pack <rostovpack@gmail.com> wrote:
[snip]
For part 2, this can actually be done using RTTI - just dynamic_cast it.
Works, thanks! I thought it wouldn't be possible to dynamic_cast a type from another library, but it seems to work... Any ideas if this can cause problems?
If I recall correctly, there is the possibility of problems using an older (much older) version of Borland C++. I read about it on some Borland help site once while designing the library. I think I've written it in a way that will overcome even those problems - but we won't find out until we've run the unit tests on more machines. Thus far, we've found no issues on any compiler. That sounds comfortable. I read about problems with any_cast where typeid is used to compare the type in any and the type to cast to (http://tinyurl.com/38ztc4), but actually I couldn't reproduce them with VC8, darwin and gcc.
Hi Jeremy, today I was able to reproduce them. I had to switch from cmake to qmake (on linux, gcc-4.1), and with that my compiler options switched, too. I think I figured out two things, to make the above work. First, the executable needs to be linked with "-rdynamic". With that flag enabled, dlopen merges the weak symbols from the loaded library with the ones from the executable. (including rtti-information). Second, the call to dlopen a library should be passed RTLD_GLOBAL. With that flag enabled, symbols from this library are candidates for merging (which again seems to remove doubled rtti symbols). Only with that set I was able to dynamic_cast "between" shared libraries. Maybe its worth mentioning that in the docs of boost::extension. Do you have an idea how this is done on windows? Cheers, Stephan