\ Extend : and ; with special code:

: entry-extension ( c-addr u -- ) 
\ c-addr u is the name of the current definition 
  ." Entering " type cr 
; 
 
: exit-extension ; 
 
: old: : ; 
 
: : 
  >in @ >r  :  r> >in ! 
  parse-word postpone sliteral 
  postpone entry-extension ; 
 
old: old; 
  postpone ; 
; immediate 
 
old: ; 
  postpone exit-extension 
  postpone ; 
; immediate 
 
old: exit 
  postpone exit-extension 
  postpone exit 
old; immediate