tie

• tie VARIABLE,CLASSNAME,LIST

  This function binds a variable to a package class that will provide the implementation for the variable. VARIABLE is the name of the variable to be enchanted. CLASSNAME is the name of a class implementing objects of correct type. Any additional arguments are passed to the appropriate constructor method of the class (meaning TIESCALAR , TIEHANDLE , TIEARRAY , or TIEHASH ). Typically these are arguments such as might be passed to the dbm_open() function of C. The object returned by the constructor is also returned by the tie function, which would be useful if you want to access other methods in CLASSNAME.

  Note that functions such as keys and values may return huge lists when used on large objects, like DBM files. You may prefer to use the each function to iterate over such. Example:

      # print out history file offsets
      use NDBM_File;
      tie(%HIST, 'NDBM_File', '/usr/lib/news/history', 1, 0);
      while (($key,$val) = each %HIST) {
          print $key, ' = ', unpack('L',$val), "\n";
      }
      untie(%HIST);

  A class implementing a hash should have the following methods:

      TIEHASH classname, LIST
      FETCH this, key
      STORE this, key, value
      DELETE this, key
      CLEAR this
      EXISTS this, key
      FIRSTKEY this
      NEXTKEY this, lastkey
      SCALAR this
      DESTROY this
      UNTIE this

  A class implementing an ordinary array should have the following methods:

      TIEARRAY classname, LIST
      FETCH this, key
      STORE this, key, value
      FETCHSIZE this
      STORESIZE this, count
      CLEAR this
      PUSH this, LIST
      POP this
      SHIFT this
      UNSHIFT this, LIST
      SPLICE this, offset, length, LIST
      EXTEND this, count
      DELETE this, key
      EXISTS this, key
      DESTROY this
      UNTIE this

  A class implementing a filehandle should have the following methods:

      TIEHANDLE classname, LIST
      READ this, scalar, length, offset
      READLINE this
      GETC this
      WRITE this, scalar, length, offset
      PRINT this, LIST
      PRINTF this, format, LIST
      BINMODE this
      EOF this
      FILENO this
      SEEK this, position, whence
      TELL this
      OPEN this, mode, LIST
      CLOSE this
      DESTROY this
      UNTIE this

  A class implementing a scalar should have the following methods:

      TIESCALAR classname, LIST
      FETCH this,
      STORE this, value
      DESTROY this
      UNTIE this

  Not all methods indicated above need be implemented. See perltie, Tie::Hash, Tie::Array, Tie::Scalar, and Tie::Handle.

  Unlike dbmopen, the tie function will not use or require a module for you; you need to do that explicitly yourself. See DB_File or the Config module for interesting tie implementations.

  For further details see perltie, tied VARIABLE.