3 ms·

It also has daemon methods, which solve the problem of making sure the superclass gets to do something before, or after, the subclass method runs, without the s

It also has daemon methods, which solve the problem of making sure the superclass gets to do something before, or after, the subclass method runs, without the subclass method having to request this explicitly.

mst 8y ago
Attempting to google variants on the them of "CLOS daemon methods" isn't bringing up anything recognisable as what you're describing - happen to know how to find a link? (I love it when my attempt to RTFM is defeated by my being too stupid to find the FM in the first place ;)
- TeMPOraL 8y ago
  The FM for Common Lisp is called Hyperspec, or CLHS. Just append "CLHS" to your search query. The parent is probably talking about method combinations - in particular, the method combination used by default, which supports :before, :after and :around methods. It's the first time I see the term "daemon method".
  - ScottBurson 8y ago
    I guess the term isn't as common as I thought, but it appears to have been used explicitly in the Flavor system, which was the object system used on the MIT Lisp Machines and which predated CLOS. That must be where I picked it up.
    - lispm 8y ago
      A daemon / demon was a procedure which runs when a slot is accessed / added / deleted / .... My bet is that this name was used in frame languages in the end 70s where there were if-needed, if-added, ... demons for a frame slot. Flavors probably got it from there - though I'm not sure. But the concept/term of a demon goes back to the end 60s to Hewitt's planner language and probably even earlier. Later with generic functions in CLOS, I'd guess the term wasn't used, since something like an :after method is no longer conceptually a specific demon procedure attached to a slot via a facet, but a method in a method combination.
- ScottBurson 8y ago
  Right, sorry, "daemon methods" is the collective term but may not actually appear in the documentation. There are three types, "before", "after", and "around"; there's a brief description at the bottom of this page: http://www.aiai.ed.ac.uk/~jeff/clos-guide.html http://www.aiai.ed.ac.uk/~jeff/clos-guide.html
- grzm 8y ago
  Likely someone will provide a better reference, but here’s one I found you may find useful: https://franz.com/support/documentation/8.1/doc/flavors.htm#6.0%20Mixing%20flavors https://franz.com/support/documentation/8.1/doc/flavors.htm#...
- carussell 8y ago
  From Yegge's "The Pinocchio Problem": > Great systems also have advice. There's no universally accepted name for this feature. Sometimes it's called hooks, or filters, or aspect-oriented programming. As far as I know, Lisp had it first, and it's called advice in Lisp. Advice is a mini-framework that provides before, around, and after hooks by which you can programmatically modify the behavior of some action or function call in the system. Not all advice systems are created equal. The more scope that is given to an advice system — that is, the more reach it has in the system it's advising — the more powerful the parent system will be. https://en.wikipedia.org/wiki/Advice_(programming) https://en.wikipedia.org/wiki/Advice_(programming)

mst 8y ago

Attempting to google variants on the them of "CLOS daemon methods" isn't bringing up anything recognisable as what you're describing - happen to know how to find a link? (I love it when my attempt to RTFM is defeated by my being too stupid to find the FM in the first place ;)

TeMPOraL 8y ago
The FM for Common Lisp is called Hyperspec, or CLHS. Just append "CLHS" to your search query. The parent is probably talking about method combinations - in particular, the method combination used by default, which supports :before, :after and :around methods. It's the first time I see the term "daemon method".
- ScottBurson 8y ago
  I guess the term isn't as common as I thought, but it appears to have been used explicitly in the Flavor system, which was the object system used on the MIT Lisp Machines and which predated CLOS. That must be where I picked it up.
  - lispm 8y ago
    A daemon / demon was a procedure which runs when a slot is accessed / added / deleted / .... My bet is that this name was used in frame languages in the end 70s where there were if-needed, if-added, ... demons for a frame slot. Flavors probably got it from there - though I'm not sure. But the concept/term of a demon goes back to the end 60s to Hewitt's planner language and probably even earlier. Later with generic functions in CLOS, I'd guess the term wasn't used, since something like an :after method is no longer conceptually a specific demon procedure attached to a slot via a facet, but a method in a method combination.
ScottBurson 8y ago
Right, sorry, "daemon methods" is the collective term but may not actually appear in the documentation. There are three types, "before", "after", and "around"; there's a brief description at the bottom of this page: http://www.aiai.ed.ac.uk/~jeff/clos-guide.html http://www.aiai.ed.ac.uk/~jeff/clos-guide.html
grzm 8y ago
Likely someone will provide a better reference, but here’s one I found you may find useful: https://franz.com/support/documentation/8.1/doc/flavors.htm#6.0%20Mixing%20flavors https://franz.com/support/documentation/8.1/doc/flavors.htm#...
carussell 8y ago
From Yegge's "The Pinocchio Problem": > Great systems also have advice. There's no universally accepted name for this feature. Sometimes it's called hooks, or filters, or aspect-oriented programming. As far as I know, Lisp had it first, and it's called advice in Lisp. Advice is a mini-framework that provides before, around, and after hooks by which you can programmatically modify the behavior of some action or function call in the system. Not all advice systems are created equal. The more scope that is given to an advice system — that is, the more reach it has in the system it's advising — the more powerful the parent system will be. https://en.wikipedia.org/wiki/Advice_(programming) https://en.wikipedia.org/wiki/Advice_(programming)