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Tie::SubstrHash(3)


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().

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