Re: Unexpected exists() behavior

~~Yes, that is correct behavior, try using defined and/or length instead.~~ (see update instead)

UPDATE: actually ... those will not work the way you think they will either. Usually one only needs to test for the value of a key, not the key itself. Try greping the keys from the hash, or use a foreach on the keys to see if the key in question is there or not.

Furthermore, try checking only if (exists($List{c}) ) ... exists is not autovivifying the key "c" ... checking $List{c}->{1} is what is causing the key "c" to be created.

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

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Re^2: Unexpected exists() behavior by tsmoyers (Pilgrim) on Jun 22, 2006 at 16:27 UTC
Testing for hash{priKey} before the full test is my workaround solution already in the works. It just seemed odd to me that a function with the sole purpose of testing would create an entry under the correct circumstances. Any idea when / why that would be desired behavior?	[reply]
Re^3: Unexpected exists() behavior by jeffa (Bishop) on Jun 22, 2006 at 16:51 UTC
It's not the function that is causing the key to be created as has been explained in this thread. Autovivification also allowed me to solve the problem at Migrating a 1NF table to multiple 2NF tables with more ease. jeffa L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)	[reply]
Re^4: Unexpected exists() behavior by Fletch (Bishop) on Jun 22, 2006 at 17:36 UTC
That doesn't technically count as autovivification, though; that's `undef` being treated as 0 in a numeric context. Autovivification is the automatic creation of a reference to a new anonymous hash (or array) when required to implement a multilevel data structure.</pedant> Update: And to out pedant myself, you don't necessarily have to have a multilevel structure; `my $aref; push @{ $aref }, 1;` is autovivification as well. The Uri article referenced from the node I mentioned below uses the phrasing automatically creating a reference of the appropriate type whenever a scalar containing `undef` is dereferenced. Better than what I used above. Further update: The parent did have code using `$hash{ $_ }++` and calling that autovivification. It's been removed so this now will make less sense. Ah well.	[reply] [d/l] [select]