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



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 v5.20.2                                2014-12-27                     Tie::SubstrHash(3perl)