While hacking my emacs mud client, I wanted to add some convenience functions for tweaking typefaces in a friendlier way than emacs normally allows.
The mud client stores per-mud information in a property list attached to a symbol, by convention stored in a variable called mud-current. Anything you want to know about a given mud can be determined through (get mud-current 'propertyname), for arbitrary values of propertyname.
Fonts are included in this property list, so I figured I'd need to allow people to select fonts applicable to their selected mud. completing-read is good for this sort of stuff as it stops you making typos so much.
So, how to make the completion list? (symbol-plist SYMBOL) returns a list of (propname propvalue propname propvalue ...), so I guessed I'd just do a (facep SYMBOL) on each element and add it to a list. Hmm. I could use (mapcar FUNCTION LIST) for that...
(mapcar '(lambda(x) (if (facep x) x nil)) (symbol-plist mud-current))
Doh! Problem. This gives me a whole heap of nil in my list. Easily fixed:
(delq nil (mapcar '(lambda(x) (if (facep x) x nil)) (symbol-plist mud-current)))
Right, now I have a list of faces; let's see what it looks like.
DOH! It only gives me the values, and I need the propnames as well. Actually, what I really need is to attach the propnames to the properties, and dump all of them into a list if the properties are faces, and...
(delq nil (let (y) (mapcar '(lambda(x) (if y (let ((z (cons y x))) (setq y nil) (if (facep x) z nil)) (setq y x) nil)) (symbol-plist mud-current))))
Hey, whaddya know? It works!
|Waider||I'd explain it to you, but your brain would explode.|