gistfile1.el

(defmacro macro1 (name)
  name)

(defmacro macro2 (name)
  '(name))

(defmacro macro3 (name)
  `(,name))

;; #123456789012345678901234567890123456789012345678901234567890
;; SVCLFOWLER         10101MS0120050313.........................
;; SVCLHOHPE          10201DX0320050315........................
;; SVCLTWO           x10301MRP220050329..............................
;; USGE10301TWO          x50214..7050329...............................

;; mapping SVCL dsl.ServiceCall
;;   4-18: CustomerName
;;   19-23: CustomerID
;;   24-27 : CallTypeCode
;;   28-35 : DateOfCallString

;; mapping  USGE dsl.Usage
;;   4-8 : CustomerID
;;   9-22: CustomerName
;;   30-30: Cycle
;;   31-36: ReadDate

(defclass ServiceCall ()
  ((Code :initarg :Code :initform "SVCL")
   (CustomerName :initarg :CustomerName)
   (CustomerID :initarg :CustomerID)
   (CallTypeCode :initarg :CallTypeCode)
   (DateOfCallString :initarg :DateOfCallString)))

(defmethod parse-line-for-class ((obj ServiceCall) line)
  (oset obj CustomerName (substring line 4 18))
  (oset obj CustomerID (substring line 19 23))
  (oset obj CallTypeCode (substring line 24 27))
  (oset obj DateOfCallString (substring line 28 35)))

(defmacro defmappings (class-name code &rest body)
  `(progn
     (defclass ,class-name ()
       ,(let ((res (list (list 'Code :initarg :Code :initform code))))
	  (dolist (elem body)
	    (setq res (cons (list (nth 2 elem)
				  :initarg
				  (make-symbol (concat ":" (symbol-name (nth 2 elem)))))
			    res)))
	  res))

     (defmethod parse-line-for-class ((obj ,class-name) line)
       ,@(let ((res nil))
	   (dolist (elem body)
	     (setq res (cons (list 'oset 'obj (nth 2 elem)
				   (list 'substring 'line (nth 0 elem) (nth 1 elem)))
			     res)))
	   res))))

(defmappings ServiceCall "SVCL"
  (4 18 CustomerName)
  (19 23 CustomerID)
  (24 27 CallTypeCode)
  (28 35 DateOfCallString))

(defmappings Usage "USGE"
  (4 8 CustomerID)
  (9 22 CustomerName)
  (30 31 Cycle)
  (32 36 ReadDate))

(let ((line "USGE123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890")
      (o nil))
  (cond
   ((string= "SVCL" (substring line 0 4)) (setq o (ServiceCall "1")))
   ((string= "USGE" (substring line 0 4)) (setq o (Usage "2"))))
  (parse-line-for-class o line)
  o)