Perl Style: Switch by Using do{} Creatively

Jan 1, 1998 by Tom Christiansen

• Another interesting approach to a switch statement is arrange for a do block to return the proper value:

     $amode = do {
         if     ($flag & O_RDONLY) { "r" }       # XXX: isn't this 0?
         elsif  ($flag & O_WRONLY) { ($flag & O_APPEND) ? "a" : "w" }
         elsif  ($flag & O_RDWR)   {
             if ($flag & O_CREAT)  { "w+" }
             else                  { ($flag & O_APPEND) ? "a+" : "r+" }
         }
     };
  

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Copyright © 1998, Tom Christiansen All rights reserved.