Hi, from an outside view, I find this discussion quite interesting... But IMHO the arguments about the need for C wrappers for plugins is wrong.
On Monday 23 June 2008, Henri Lesourd wrote: > > You can do that with C++, I am 100% sure of this. > > > Well, check your documentation. Mine says: > [[ > C++'s greatest weaknesses in this area is the lack of > a C++ ABI on some platforms and the lack of a native > notion of a dynamically linked library. > ]] > B. Stroustrup (interview): C++: past, present, and > future. Frontier Channels, September 2006. > > > Thus yes you can do it: but only if you wrap your C++ > classes behind a C API. When both a Texmacs binary and an independently compiled plugin want to use a given class, it should be enough to pass pointers between. For this, you use factory methods in the plugin, and the created objects can be used in the texmacs binary without any need for recompilation. E.g. when texmacs defines a C++ class Button, the plugin is free to derive from this class and define a MySuperButton, and can pass such objects to the texmacs binary via a factory method. As long as texmacs is only storing the object pointer or calling methods from the base class Button, all goes well. And when a method is virtual, you can call from texmacs directly to a C++ method in the plugin without any need of MySuperButton to be known at compile time of the texmacs binary. Magic of virtual tables ;-) So for sure, this has nothing to do with the need for C wrappers around interfaces. > Excuse me, but when I look at the dl_open() functions, I > see absolutely *nothing* which would allow me to fetch a > class contained inside a .so and call its constructor and > methods. No. For this, you have to use _one single_ C function which can be searched for in dl_open. This C function can return a function pointer to a C++ factory method, which itself can pass created C++ objects around. By the way, this is also the method used by Qt itself for its plugins. But it is really simple to implement, and there is no need to use Qt plugins for this. texmacs itself does not need to be linked with Qt. > Thus what you say seems interesting, but currently, it > is a little bit too much fuzzy to be useable information. Perhaps I am missing something here? Cheers, Josef _______________________________________________ Texmacs-dev mailing list Texmacs-dev@gnu.org http://lists.gnu.org/mailman/listinfo/texmacs-dev
