Tie::SubstrHash(3)					    Tie::SubstrHash(3)

NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

	 require Tie::SubstrHash;

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

DESCRIPTION    [Toc]    [Back]

     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    [Toc]    [Back]

     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.


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