But defined doesn't do anything to prevent autovivification either. Look at this: 


my %hash = ( Key1 => { john => 1, pete => 2 },
             Key2 => { frank => 3, howard => 4 } );
print "Exists!\n" if defined $hash{Key7}{ted};
print "Key7 exists!\n" if exists $hash{Key7};

[download]

Here you're testing the definedness of a key that doesn't exist: $hash{Key7}{ted}, and then you're going to check to see if $hash{Key7} autovivified. Guess what? It did, just the same as when we used exists to check for the existance of $hash{Key7}{ted}. The same conditions that will cause exists to autovivify a hash element will also cause defined to autovivify a hash element. exists doesn't have any more possibility to do that than any other function.


Dave

In reply to Re^4: need explanation of @foo{@bar} = (); (hash slice) by davido
in thread need explanation of @foo{@bar} = (); (hash slice) by Anonymous Monk

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