wip(emacs): Abstract strategy-running

- Show docs and goto def are confirmed working

users/crumb/programs/emacs/lib/syd-strategies.el

@@ -0,0 +1,37 @@
+;; syd-strategies.el -*- lexical-binding: t; -*-
+
+(require 'syd-text)
+
+;; :documentation : Identifier -> Marker
+(defvar-local syd-strat--strategies nil)
+
+(defun syd-strat-try-functions-wrapped (wrapper fns &rest args)
+  "For each FN in FNS, call WRAPPER with the arguments FN followed by ARGS,
+until a FN returns non-nil."
+  (cl-loop for fn in fns
+           with r = nil
+           do (setq r (apply wrapper fn args))
+           until r
+           finally return r))
+
+(defun syd-strat--set-strategies (category strategies)
+  (cl-loop for ref in-ref syd-strat--strategies
+           until (eq category (car ref))
+           finally do (pp ref)))
+
+(defun syd-set-strategies (modes &rest args)
+  (dolist (mode (ensure-list modes))
+    (let ((hook (intern (format "%s-hook" mode)))
+          (fn-name (intern (format "syd-strat--init-for-%s-h" mode))))
+      (unless (cl-evenp (length args))
+        (signal 'wrong-number-of-arguments args))
+      ;; We use this `defalias' incantation instead of a raw `fset' because the
+      ;; former will properly associate a source location to the definition.
+      (defalias fn-name
+        (function
+         (lambda ()
+           (cl-loop for (category strategies) on args by (lambda (x) (-drop 2 x))
+                    do (syd-strat--set-strategies category strategies)))))
+      (add-hook hook fn-name))))
+
+(provide 'syd-strategies)