Beefy Boxes and Bandwidth Generously Provided by pair Networks
Do you know where your variables are?

Re: non-autovivifing hash (not read-only keys)

by tye (Sage)
on Jul 02, 2003 at 18:03 UTC ( #270892=note: print w/replies, xml ) Need Help??

in reply to non-autovivifing hash

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

Log In?

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://270892]
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others meditating upon the Monastery: (3)
As of 2023-12-10 10:46 GMT
Find Nodes?
    Voting Booth?
    What's your preferred 'use VERSION' for new CPAN modules in 2023?

    Results (39 votes). Check out past polls.