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Hash-SafeKeys
Every hash variable in Perl has its own internal iterator,
accessed by the builtin C<each>, C<keys>, and C<values>
functions. The iterator is also implicitly used whenever
the hash is evaluated in list context. The iterator is
"reset" whenever C<keys> or C<values> is called on a hash,
including the implicit calls when the hash is evaluated in
list context. That makes it dangerous to do certain hash
operations inside a C<while ... each> loop:
while (my($k,$v) = each %hash) {
...
@k = sort keys %hash; # Infinite loop!
@v = grep { /foo/ }, values %hash; # Ack!
print join ' ', %hash; # Run away!
}
C<Hash::SafeKeys> provides alternate functions to access
the keys, values, or entire contents of a hash in a way
that does not reset the iterator, making them safe to use
in such contexts:
while (my($k,$v) = each %hash) {
...
@k = sort safekeys %hash; # Can do
@v = grep { /foo/ }, safevalues %hash; # No problem
print join ' ', safecopy %hash; # Right away, sir
}
INSTALLATION
To install this module, run the following commands:
perl Makefile.PL
make
make test
make install
SUPPORT AND DOCUMENTATION
After installing, you can find documentation for this module with the
perldoc command.
perldoc Hash::SafeKeys
You can also look for information at:
RT, CPAN's request tracker (report bugs here)
http://rt.cpan.org/NoAuth/Bugs.html?Dist=Hash-SafeKeys
AnnoCPAN, Annotated CPAN documentation
http://annocpan.org/dist/Hash-SafeKeys
CPAN Ratings
http://cpanratings.perl.org/d/Hash-SafeKeys
Search CPAN
http://search.cpan.org/dist/Hash-SafeKeys/
LICENSE AND COPYRIGHT
Copyright (C) 2012-2016 Marty O'Brien
This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
by the Free Software Foundation; or the Artistic License.
See http://dev.perl.org/licenses/ for more information.
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