Tie::IxHash(3) | User Contributed Perl Documentation | Tie::IxHash(3) |
Tie::IxHash - ordered associative arrays for Perl
# simple usage use Tie::IxHash; tie HASHVARIABLE, 'Tie::IxHash' [, LIST]; # OO interface with more powerful features use Tie::IxHash; TIEOBJECT = Tie::IxHash->new( [LIST] ); TIEOBJECT->Splice( OFFSET [, LENGTH [, LIST]] ); TIEOBJECT->Push( LIST ); TIEOBJECT->Pop; TIEOBJECT->Shift; TIEOBJECT->Unshift( LIST ); TIEOBJECT->Keys( [LIST] ); TIEOBJECT->Values( [LIST] ); TIEOBJECT->Indices( LIST ); TIEOBJECT->Delete( [LIST] ); TIEOBJECT->Replace( OFFSET, VALUE, [KEY] ); TIEOBJECT->Reorder( LIST ); TIEOBJECT->SortByKey; TIEOBJECT->SortByValue; TIEOBJECT->Length;
This Perl module implements Perl hashes that preserve the order in which the hash elements were added. The order is not affected when values corresponding to existing keys in the IxHash are changed. The elements can also be set to any arbitrary supplied order. The familiar perl array operations can also be performed on the IxHash.
The standard "TIEHASH" mechanism is available. This interface is recommended for simple uses, since the usage is exactly the same as regular Perl hashes after the "tie" is declared.
This module also provides an extended object-oriented interface that can be used for more powerful operations with the IxHash. The following methods are available:
If a single argument is given, returns the single key corresponding to the index. This is usable in either scalar or list context.
If a single argument is given, returns the single value corresponding to the index. This is usable in either scalar or list context.
If a single argument is given, returns the single index corresponding to the key. This is usable in either scalar or list context.
use Tie::IxHash; # simple interface $t = tie(%myhash, 'Tie::IxHash', 'a' => 1, 'b' => 2); %myhash = (first => 1, second => 2, third => 3); $myhash{fourth} = 4; @keys = keys %myhash; @values = values %myhash; print("y") if exists $myhash{third}; # OO interface $t = Tie::IxHash->new(first => 1, second => 2, third => 3); $t->Push(fourth => 4); # same as $myhash{'fourth'} = 4; ($k, $v) = $t->Pop; # $k is 'fourth', $v is 4 $t->Unshift(neg => -1, zeroth => 0); ($k, $v) = $t->Shift; # $k is 'neg', $v is -1 @oneandtwo = $t->Splice(1, 2, foo => 100, bar => 101); @keys = $t->Keys; @values = $t->Values; @indices = $t->Indices('foo', 'zeroth'); @itemkeys = $t->Keys(@indices); @itemvals = $t->Values(@indices); $t->Replace(2, 0.3, 'other'); $t->Delete('second', 'zeroth'); $len = $t->Length; # number of key-value pairs $t->Reorder(reverse @keys); $t->SortByKey; $t->SortByValue;
You cannot specify a negative length to "Splice". Negative indexes are OK, though.
Indexing always begins at 0 (despite the current $[ setting) for all the functions.
Addition of elements with keys that already exist to the end of the IxHash must be controlled by a switch.
Provide "TIEARRAY" interface when it stabilizes in Perl.
Rewrite using XSUBs for efficiency.
Gurusamy Sarathy gsar@umich.edu
Copyright (c) 1995 Gurusamy Sarathy. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Version 1.23
perl(1)
2024-04-13 | perl v5.34.0 |