> Am 07.02.2021 um 09:45 schrieb Hans Hübner <hans.hueb...@gmail.com>:
>
> Am So., 7. Feb. 2021 um 09:35 Uhr schrieb Manfred Bergmann
> <manfred.bergm...@me.com>:
> > Am 07.02.2021 um 09:23 schrieb Hans Hübner <hans.hueb...@gmail.com>:
> >
> > Am So., 7. Feb. 2021 um 09:20 Uhr schrieb Manfred Bergmann
> > <manfred.bergm...@me.com>:
> > But fundamentally, you also can’t create an instance of a class in Common
> > Lisp from just the symbol. The class definition must be known.
> >
> > This simply is untrue. You can use FIND-CLASS to find a class named by a
> > symbol and then instantiate it.
>
> Well, OK. Sure. But when I do that I have again a dependency on the concrete
> class, or? And it would be similar as knowing the class right from the start.
>
> You don't. You have a dependency on the name of a class. The name could
> refer to two entirely different classes between invocations of FIND-CLASS.
> The name could also come from an external source. Thus, this is purely a
> run-time dependency and it would be quite possible that FIND-CLASS returns
> NIL if given a symbol that does not designate a currently-defined class.
OK, nice.
This is probably why make-instance `foo can work instead of this boilerplate
Abstract Factory in Java.
Actually looks like FIND-CLASS is the simple version of dependency-injection.
Manfred
