


Tie::SubstrHash(3Perl Programmers Reference GuTie::SubstrHash(3p)


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

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 table
       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 reference 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 table.

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 ini-
       tialization parameters.

       The hash does not support exists().




















2001-05-24                 perl v5.6.1                          1


