Yes, it works. 
use strict;
use warnings;
use Data::Dumper;


my $hash_ref = {1 => 2, 3 => 4};
BLOCK: {
    local $hash_ref->{1} = 5;
    print Dumper $hash_ref;
}

print Dumper $hash_ref;

[download]
The clearest documentation on this, IMHO, is Temporary Values via local() in perlsub. Essentially, you can localize any hash or array value, which will be restored once you exit the current scope. This trick is frequently used with the %SIG handlers. When you do the localization, you are localizing the element in the hash that the reference points at.

Update: When to Still Use local() is actually the better doc link for this question.

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

In reply to Re: use 'local' modifier to hashref element by kennethk
in thread use 'local' modifier to hashref element by schetchik

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