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Whenever a non-existing hash or array element is used in anything but a simple context, it's autovivificated. The *default* is to autovivificate - it's just that the exceptions happen to be the most often used cases, so it's a surprise when perl autovivifies.
#!/usr/bin/perl use strict; use warnings; my %hash; sub X {} my $x; $x = exists $hash{key1}; printf "key1 %sautovivified\n", exists $hash{key1} ? "" : "not "; $x = $hash{key2}; printf "key2 %sautovivified\n", exists $hash{key2} ? "" : "not "; $x = exists $hash{key4}{key3}; printf "key3 %sautovivified\n", exists $hash{key4}{key3} ? "" : "not +"; printf "key4 %sautovivified\n", exists $hash{key4} ? "" : "not "; ($x) = @hash{key5}; printf "key5 %sautovivified\n", exists $hash{key5} ? "" : "not "; ($x) = @hash{"key6", "key7"}; printf "key6 %sautovivified\n", exists $hash{key6} ? "" : "not "; printf "key7 %sautovivified\n", exists $hash{key7} ? "" : "not "; X($hash{key8}); printf "key8 %sautovivified\n", exists $hash{key8} ? "" : "not "; X(@hash{key9}); printf "key9 %sautovivified\n", exists $hash{key9} ? "" : "not "; X(@hash{"keyA","keyB"}); printf "keyA %sautovivified\n", exists $hash{keyA} ? "" : "not "; printf "keyB %sautovivified\n", exists $hash{keyB} ? "" : "not "; __END__ key1 not autovivified key2 not autovivified key3 not autovivified key4 autovivified key5 not autovivified key6 not autovivified key7 not autovivified key8 not autovivified key9 autovivified keyA autovivified keyB autovivified
Perl --((8:>*

In reply to Re^2: Autovivification sucking the life out of me by Perl Mouse
in thread Autovivification sucking the life out of me by shenme

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