Autoconf

[Parisse Bernard]

> 
> IMHO, users of GiNaC should not reply on the internal representation of
> algebraic objects (even that op(nops()-1) thing is suspicious to me), because
> that representation has changed, and will change sometime in the future.
> Extensions to GiNaC in the form of new classes, however, may benefit from
> or even require access to the internal representation, in which case the
> C++ "friend" mechanism can be used.

The main problem is however that the friend declaration must be
present in GiNaC source code not in the extension source code.
Anyway, I don't see any difference in accessing internal representation
via a friend class or via members as soon as it is documented that
these members might change in the future. I don't like bureaucraty!