SE701:Screencasts:scar107:OptionalParameters

Can be downloaded from here. Note - new and improved! Well, kinda. It's still not particularly exciting, but I made the resolution bigger so it's easier to see/read. Ooooh!

Cheatsheet:

• &optional: specifies that the following unnamed argument is optional

 (defun do-stuff (&optional on-something))

• &key: specifies that the following argument is named

 (defun do-stuff (&key (thing "hello"))
  (print thing))
 
 (do-stuff :thing "nahhh")

• &rest: specifies that a variable number of arguments should be assigned to a list in the following argument

 (make-list (&rest args)
  (for i in args do
   (print i)))

Choice!