Thank you for sending this. I had just started, so look at the time you saved me!
—Scott
On Feb 6, 2021, at 10:17 AM, Luís Oliveira luismbo@gmail.com wrote:
On Sat, 6 Feb 2021 at 13:46, Manfred Bergmann manfred.bergmann@me.com wrote:
Does anyone know what Peter Norvig had in mind when he said that metaclasses can be used instead of Abstract Factory pattern?
Are you talking about slides 12 and 13? Peter does not mention metaclasses there or anywhere else in his slides. I believe his point is that make-instance is the factory. Classes are first-class values and make-instance accepts a class as its first argument. If you use qt-backend, gtk-backend, motif-backend classes, at some point you can make the decision about which class to instantiate and pass it to make-instance. He categorizes this pattern as invisible, which might explain why you're having trouble seeing it. :-)
Cheers, Luís