Filters

• Suppose you want to store complex data structures in a DB_File

• This doesn't work:

 $hash{numbers} = [1, 4, 2, 8, 5, 7];

• The array is converted to a string, and the string is stored:

 print $hash{numbers}, "\n";
 ARRAY(0x8118d9c) 

 $aref = $hash{numbers};
 print "@$aref\n";

 Can't use string ("ARRAY(0x8118d9c)") as an ARRAY ref
  while "strict refs" in use...

• This is a drawback of all DBM implementations

  • And indeed of the Unix operating system

  • There's no OS support for storing anything except a lifeless byte sequence