John Morrison john.nmi.morrison@gmail.com writes:
Hi All;
This is probably a dumb question, but here goes.
John Alan McDonald (Hi, John, if you're on this list!) has graciously consented to let me try to revive some almost 20 year old CL software ( Arizona http://home.comcast.net/~johnamcdonald/jamcdonald0/az93.pdf). SBCL doesn't seem to like type-related declarations in defgeneric forms (per the spechttp://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html#defgeneric). And there are a lot of defgenerics of the form:
(declaim (declaration :returns)) ;; OK, only once, but then used repeatedly...
(defgeneric interactor-role-cursor (interactor role) (declare (type Interactor interactor) (type (or Interactor-Role Null) role) (:returns (type xlib:Cursor))) (:documentation "Returns the cursor to be used when this Role is current."))
(defmethod interactor-role-cursor ((interactor Interactor) (role Interactor-Role)) "The default cursor" (xlt:window-cursor (interactor-window interactor) :target))
I did certainly benefit from some of the runtime errors generated as a result of the type declarations of some of the defmethods and defuns in my efforts to update the clx parts of the software.
What is best practice, then, as regards trying to provide useful type-related information associated with generic functions? Or have I been so brain-damaged by C++/Java/etc that I am thinking about the problem-space entirely the wrong way, and thus my solution-space question is entirely meaningless?
The portable equivalent would be (declaim (ftype (function (interactor (or interactor-role null)) xlib:cursor) interactor-role-cursor))