Have several implementations for determining the dependence chain for a derived mode once the mode has been loaded. What would be the most convenient to use and what improvements can I do?
Have difficulty understanding the workings of dependence-chain-a, specifically the line (while (progn. How is the while loop functioning in the case of dependence-chain-a?
(defun dependence-chain-a (mode)
"Return the chain of derived modes for MODE."
(interactive)
(let (chain)
(while (progn
(push mode chain)
(let* ( (parent (get mode 'derived-mode-parent))
(parentfn (symbol-function parent)) )
(setq mode (if (and parentfn (symbolp parentfn))
parentfn
parent)))))
(nreverse chain)))
;;--------
(defun dependence-chain-b (mode)
"Return a list of the ancestor modes that MODE is derived from."
(interactive)
(let ( (modes ())
(parent nil) )
(while (setq parent (get mode 'derived-mode-parent))
(push parent modes)
(setq mode parent))
(setq modes (nreverse modes))))
;;--------
(defun dependence-chain-c (mode)
(interactive (list major-mode))
(defun iter (mode)
(and mode
(cons mode
(iter (get mode 'derived-mode-parent)))))
(message "%s" (iter mode)))
