How to define operators in oct-files

[Lukas Reichlin]

Dear Octave Community

What is the most recent/recommended way of defining operators, e.g. binary 
plus, for classes implemented in oct-files? Are there good code examples? The 
sparsersb package is rather confusing to me and the symbolic package seems to 
be outdated.
Currently I'm trying to understand the usage of the macros
DEFBINOP(op_add, …
INSTALL_BINOP

Thanks for any help
Lukas