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



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 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 initialization parameters.

       The hash does not support exists().



perl v5.16.2                                     2012-08-26                             Tie::SubstrHash(3pm)