;; trace-func
;; trace individual functions

(setq trace-func.level 0)

;; (trace-func foo)
;; will trace all calls to foo, printing arguments passed, and result returned
;; (trace-func func expr)
;; trace func and print value of expr at invocation

(df trace-func tfargs
    (with (func (# 0 tfargs)
	   old-func-name (atom (+ "%%OLD-" func))
			 res ())
      (if (boundp old-func-name)
	  (trigger-error "already traced function: " func))
      (set old-func-name (eval func))
      (set func
	   (eval
	    (list 'lambdaq 'args
		  (list '? 'trace-func.level ">" (+ "" func) "> " 'args
			" "(# 1 tfargs)"\n")
		  '(setq trace-func.level (+ 1 trace-func.level))
		  (list ': 'res
			(list 'eval (list '+
					  (list 'list (eval func)) 'args)))
		  '(setq trace-func.level (+ -1 trace-func.level))
		  (list '? 'trace-func.level "<" (+ "" func) "< " 'res "\n")
		  'res)))))

;; (untrace-func foo)
;; will remove tracing of function foo

(df untrace-func (func)
    (with (old-func-name (atom (+ "%%OLD-" func)))
      (if (not (boundp old-func-name))
	  (trigger-error (+ "" old-func-name) " was not traced")
	(set func (eval old-func-name))
	(unbind  old-func-name))))