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While the read-only keys solutions (Tie::StrictHash and from Hash::Util) provide one method of preventing autovivification for hashes, they also prevent normal key creation.

What I've long wanted was a 'no autovivify;' pragma that would prevent autovivification in the scope where it is used (for both hashes and arrays) but that would not prevent normal hash key insertion.

I like to be able to assign new keys in the normal manner:

$hash{key}= 'value';
but I often prefer to not create new keys via autovivification, which is different:
no autovivify; my %hash; # Examples of normal key insertion: $hash{key1}= 'value'; # succeeds $hash{key2}= {}; # succeeds $hash{key2}{key3}= 'value'; # succeeds # Examples of autovivification: $hash{key4}{key3}= 'value'; # should fail! $hash{key5}[0]= 1; # should fail!
Sometimes it is very nice to be very strict in how you code. It can often find lots of bugs for you. That is why we have use strict;. Perl could really use a similar tool for optionally turning off autovivification. I'd certainly make a lot of use of it (and I've found several bugs the hard way that would have been caught quite easily if I'd had such an option).

                - tye

In reply to Re: non-autovivifing hash (not read-only keys) by tye
in thread non-autovivifing hash by bobdeath

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