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IRIX Base Documentation 1998 November
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IRIX 6.5.2 Base Documentation November 1998.img
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Tie::Hash.z
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Tie::Hash
Wrap
Text File
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1998-10-30
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4KB
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133 lines
TTTTiiiieeee::::::::HHHHaaaasssshhhh((((3333)))) TTTTiiiieeee::::::::HHHHaaaasssshhhh((((3333))))
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Tie::Hash, Tie::StdHash - base class definitions for tied hashes
SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
package NewHash;
require Tie::Hash;
@ISA = (Tie::Hash);
sub DELETE { ... } # Provides needed method
sub CLEAR { ... } # Overrides inherited method
package NewStdHash;
require Tie::Hash;
@ISA = (Tie::StdHash);
# All methods provided by default, define only those needing overrides
sub DELETE { ... }
package main;
tie %new_hash, 'NewHash';
tie %new_std_hash, 'NewStdHash';
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
This module provides some skeletal methods for hash-tying classes. See
the _p_e_r_l_t_i_e manpage for a list of the functions required in order to tie
a hash to a package. The basic TTTTiiiieeee::::::::HHHHaaaasssshhhh package provides a new method,
as well as methods TIEHASH, EXISTS and CLEAR. The TTTTiiiieeee::::::::SSSSttttddddHHHHaaaasssshhhh package
provides most methods required for hashes in the _p_e_r_l_t_i_e manpage. It
inherits from TTTTiiiieeee::::::::HHHHaaaasssshhhh, and causes tied hashes to behave exactly like
standard hashes, allowing for selective overloading of methods. The new
method is provided as grandfathering in the case a class forgets to
include a TIEHASH method.
For developers wishing to write their own tied hashes, the required
methods are briefly defined below. See the the _p_e_r_l_t_i_e manpage section
for more detailed descriptive, as well as example code:
TIEHASH classname, LIST
The method invoked by the command tie %hash, classname. Associates a
new hash instance with the specified class. LIST would represent
additional arguments (along the lines of the _A_n_y_D_B_M__F_i_l_e manpage and
compatriots) needed to complete the association.
STORE this, key, value
Store datum _v_a_l_u_e into _k_e_y for the tied hash _t_h_i_s.
PPPPaaaaggggeeee 1111
TTTTiiiieeee::::::::HHHHaaaasssshhhh((((3333)))) TTTTiiiieeee::::::::HHHHaaaasssshhhh((((3333))))
FETCH this, key
Retrieve the datum in _k_e_y for the tied hash _t_h_i_s.
FIRSTKEY this
Return the (key, value) pair for the first key in the hash.
NEXTKEY this, lastkey
Return the next (key, value) pair for the hash.
EXISTS this, key
Verify that _k_e_y exists with the tied hash _t_h_i_s.
DELETE this, key
Delete the key _k_e_y from the tied hash _t_h_i_s.
CLEAR this
Clear all values from the tied hash _t_h_i_s.
CCCCAAAAVVVVEEEEAAAATTTTSSSS
The the _p_e_r_l_t_i_e manpage documentation includes a method called DESTROY as
a necessary method for tied hashes. Neither TTTTiiiieeee::::::::HHHHaaaasssshhhh nor TTTTiiiieeee::::::::SSSSttttddddHHHHaaaasssshhhh
define a default for this method. This is a standard for class packages,
but may be omitted in favor of a simple default.
MMMMOOOORRRREEEE IIIINNNNFFFFOOOORRRRMMMMAAAATTTTIIIIOOOONNNN
The packages relating to various DBM-related implemetations (_D_B__F_i_l_e,
_N_D_B_M__F_i_l_e, etc.) show examples of general tied hashes, as does the the
_C_o_n_f_i_g manpage module. While these do not utilize TTTTiiiieeee::::::::HHHHaaaasssshhhh, they serve
as good working examples.
PPPPaaaaggggeeee 2222