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Manpages Tie::HashSection: Perl Programmers Reference Guide (3perl)Updated: 2001-02-22 Index Return to Main Contents NAMETie::Hash, Tie::StdHash - base class definitions for tied hashesSYNOPSISpackage 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'; DESCRIPTIONThis module provides some skeletal methods for hash-tying classes. See perltie for a list of the functions required in order to tie a hash to a package. The basic Tie::Hash package provides a "new" method, as well as methods "TIEHASH", "EXISTS" and "CLEAR". The Tie::StdHash package provides most methods required for hashes in perltie. It inherits from Tie::Hash, 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 perltie section for more detailed descriptive, as well as example code:
CAVEATSThe perltie documentation includes a method called "DESTROY" as a necessary method for tied hashes. Neither Tie::Hash nor Tie::StdHash define a default for this method. This is a standard for class packages, but may be omitted in favor of a simple default.MORE INFORMATIONThe packages relating to various DBM-related implementations (DB_File, NDBM_File, etc.) show examples of general tied hashes, as does the Config module. While these do not utilize Tie::Hash, they serve as good working examples.
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