6 The DBG Package

print-handler-frames

Variable

Summary

Controls whether handler frames are printed in debugger output.

Package

dbg

Initial Value

nil

Description

This variable is used by the debugger when it displays the stack frames. Handler frames are created by error handlers (see the LispWorks User Guide), and are normally not shown by the debugger. However if*print-handler-frames* is set tot then the handler frames are displayed.

Example

USER 162 > (setq lw:*print-handler-frames* t)

T 
USER 163 > (defun test (n)
   (handler-case (fn-to-use n)
(type-error () (format t "~%Type error~%") 0)))

TEST 
USER 164 > (test #C(1 1))

Error: Undefined function: FN-TO-USE, with args
  (#C(1 1)) 

1 (continue) Call FN-TO-USE again
  2 (abort) return to top loop level 0.

Type :c followed by a number to proceed

USER 165 : 1 > :b 10 
Catch frame: (NIL) 
Catch frame: #:|block-catcher-1854| 
Call to *%UNDEFINED-FUNCTION-FUNCTION  : 
Call to %EVAL  : 
Call to RETURN-FROM  : 
Call to %EVAL  : 
Call to EVAL-AS-PROGN  : 
Handler frame: ((TYPE-ERROR %LEXICAL-CLOSURE%   
 (LAMBDA 
  (CONDITIONS::TEMP)  
  (GO #:|lambda-633|)) 
 ((#:|lambda-632|) (N . #)) 
 NIL ((#:|lambda-631|) (TEST)) 
 ((#:|lambda-633| # #)))) 
Catch frame: "<* Catch All Object *>" 
Call to LET  :

Notes
: *print-handler-frames* is an extension to Common Lisp.