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8.119. Hash::Util

Offers a
selection of general-utility hash subroutines. Starting with Perl
5.8, hashes allow you to restrict access to the data
that's stored in the hash. Individual keys can be
locked so they cannot be deleted, nor can their values be changed.
Hash::Util is largely intended to replace the deprecated
pseudo-hashes.

For example:

#!/usr/local/bin/perl -w
%hash = (foo => 42, bar => 23);
lock_keys(%hash);
# Now, try to set %hash{'something'}
while(my($key, $value) = each %hash) {
print "$key -> $value\n";
}
unlock_keys(%hash);

You can lock specific values as follows:

#!/usr/local/bin/perl -w
%hash = (foo => 42, bar => 23);
lock_key(%hash, 'foo');
# Now, try to set 'foo' and see what happens
unlock_keys(%hash, 'foo');

8.118. Getopt::Std		8.120. I18N::Collate

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