--, ++, -=, += and friends shouldn't complain about undefined variables, according to documentation.
That's why perl -wMstrict -e'my $a = undef; $a++;' does not complain, nor does $hash{foo}++.

But when the hash in quesion is tied AND a hashref AND in another hash, perl suddenly _does_ complain.
I tried narrowing it down to the essential bits again, succesfully this time.
As you can see in the paste below, everything is fine with the second one, which would be exactly the same if it were tie()d.

2;0 juerd@ouranos:~$ cat test.pl
#!/usr/bin/perl -w
use GDBM_File;
use strict;
unlink 'karmatest';

my $hashref = { hash => {} };
$hashref->{object} = tie %{ $hashref->{hash} }, 'GDBM_File', 'karmates
+t', GDBM_WRCREAT, 0640;

sub resolve {
    return \ $hashref->{hash}{$_[0]};
}

# Warning!
${ resolve('this one does not exist') }  +=  2;

# now, the same, but without tie:

my $second = { hash => {} };

sub resolve_again {
    return \ $second->{hash}{$_[0]};
}

# No warning!
${ resolve('this one does not exist') }  +=  2;
2;0 juerd@ouranos:~$ perl test.pl
Use of uninitialized value in addition (+) at test.pl line 13.

[download]


I think my inability to express what I mean in English is the biggest problem here :( 

2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$

[download]

In reply to Re: Re: Re: Autovivification not working? by Juerd
in thread Autovivification not working? by Juerd

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