Tie::SubstrHash

Tie::SubstrHash(3)     Perl Programmers Reference Guide	   Tie::SubstrHash(3)



NAME
       Tie::SubstrHash - Fixed-table-size, fixed-key-length hashing

SYNOPSIS
	   require Tie::SubstrHash;

	   tie %myhash, ’Tie::SubstrHash’, $key_len, $value_len, $table_size;

DESCRIPTION
       The Tie::SubstrHash package provides a hash-table-like interface to an
       array of determinate size, with constant key size and record size.

       Upon tying a new hash to this package, the developer must specify the
       size of the keys that will be used, the size of the value fields that
       the keys will index, and the size of the overall table (in terms of
       key-value pairs, not size in hard memory). These values will not
       change for the duration of the tied hash. The newly-allocated hash ta-
       ble may now have data stored and retrieved. Efforts to store more than
       $table_size elements will result in a fatal error, as will efforts to
       store a value not exactly $value_len characters in length, or refer-
       ence through a key not exactly $key_len characters in length. While
       these constraints may seem excessive, the result is a hash table using
       much less internal memory than an equivalent freely-allocated hash ta-
       ble.

CAVEATS
       Because the current implementation uses the table and key sizes for
       the hashing algorithm, there is no means by which to dynamically
       change the value of any of the initialization parameters.

       The hash does not support exists().



perl v5.8.8			  2001-09-21		   Tie::SubstrHash(3)