define-insertion-template.el

(defmacro define-insertion-template (name template)
  (destructuring-bind (vars fmt)
      (parse-template template)
    (let* ((syms (mapcar 
		  (lambda (v)
		    `(,v ,(gensym)))
		  (remove-duplicates vars))))
      `(defun ,name ()
	 (interactive)
	 (let ,(mapcar 'second syms) 
	   ,@(mapcar
	      (lambda (ss)
		`(setf ,(second ss) (read-from-minibuffer ,(format "template var %s:" (car ss)))))
	      syms)
	   (insert
	    (format
	     ,fmt
	     ,@(mapcar
		(lambda (var)
		  (second (assoc var syms)))
		vars))))))))

(defun parse-template (template)
  (let ((len (length template))
	(pos 0)
	vars 
	fmt)
    (loop
       while (< pos len)
       with prev = nil
       for ch = (elt template pos)
       do
	 (cond
	   ((and prev (= ch ?$) (= prev ?$))
	    (push ?$ fmt)
	    (setf prev nil))
	   ((= ch ?$)
	    (setf prev ?$))
	   ((and prev  (= prev ?$) (= ch ?{))
	    (let ((str (substring template (1+ pos) (position ?} template :start pos))))
	      (setf pos (position ?} template :start pos))
	      (push ?% fmt)
	      (push ?s fmt)
	      (push (intern str) vars)))
	   (t
	    (push ch fmt)
	    (setf prev ch)))
	 (incf pos))
    (list (nreverse vars)
	  (coerce (nreverse fmt) 'string))))

;; example	    
(define-insertion-template insert-hoge
    "aaa ${hoge} bbb ${hoge} ${fuga}")
;; M-x insert-hoge 
;; minibuffer) template var hoge: ppp
;; minibuffer) template var fuga: bbb
;; => aaa ppp bbb ppp bbb