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Object-Oriented Languages

• Redefined class methods via dynamic scoping.
  • class NAT = record
       var NUM: newint;
       proc SUCC = NUM := @NUM+1;
       proc PLUSTWO = call SUCC; call SUCC
    end
  • class INT = inherits NAT with record
       var ISNEG: newbool
       proc SUCC =
          if not ISNEG then NUM:=@NUM+1
          else NUM:=@NUM-1; ...; fi
    end
  • In context INT, PLUSTWO should call new SUCC!
  • In context NAT, PLUSTWO should call old SUCC.

Static scoping does not support this!