Hello Mathieu, IOhannes, Hans, Marvin,
Thanks for all your informed answers.
I was considering C++ just for programming comfort. I know that everything can be done in C but it is so clumsy for making class-like things. If Pd would be conceived today, would it be written in C?
But indeed, C++ ABI complexities make it harder to get a C++ lib working always and everywhere. I've come across the MSVC/GNU incompatibility, but didn't know about the GNU version conflicts mentioned by Mathieu.
So, the comfort of C++ programming and the time saved during development may be outweighed by troubles in deployment? I have to think twice... My lib should easily build and run wherever Pd runs.
I started reading Axel-Tobias Schreiner's 'Object-Oriented Programming with ANSI-C', found via Marvin's link. The title made me enthusiastic for a moment. I like C. But for OOP? It's a lot of dull administration.
Fortunately I've time to reflect a bit more on the options, this lib need not be written today or tomorrow. Thanks again for all the advice.
Katja