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().