I'm new to gdbm and I would like to use it in Perl. I know that Perl ships by default with a module for that (GDBM_File). Now, when I try the simplest example possible, namely:
#!/usr/bin/perl
use strict;
use warnings;
use GDBM_File;
my $dbfile = '/tmp/test.gdbm';
my $ok = tie(my %db, 'GDBM_File', $dbfile, &GDBM_WRCREAT, 0664);
die "can't tie to $dbfile for WRCREAT access: $!" unless $ok;
$db{test} = 1;
untie %db;
and execute it I get the following warning:
untie attempted while 1 inner references still exist at ./gdbm-test line 13.
I read the perl documentation (see the "untie gotcha" in the provided link) but that explanation does not seem to apply here since it is clear that %db has no references anywhere in the code pointing to it.
Nonetheless the code seems to work since when I inspect the database file I get the correct result:
bash$ echo list | gdbmtool /tmp/test.gdbm
test 1
Why does this warning appear and how can I get rid of it?
I think that this is, in fact, a manifestation of the gotcha that you point to. The documentation for tie() says this:
The object returned by the constructor is also returned by the tie function
So your $ok contains a reference to the object, and you should undefine that before calling untie().
undef $ok;
untie %db;