Peace be upon the Monksters;
I have a simple (or so I thought) class ('FileHash') that ties a hash to a file,
reading data into the hash upon instantiation, and writing the hash
out to the file when DESTROYed.
I want to use the class for several hashes
e.g.
my (%pwds, %boxes);
tie (%pwds, 'FileHash', "$dir/pwds");
tie (%boxes, 'FileHash', "$dir/boxes");
but the second call to
tie clears out any
data that may have been read into the first hash and replaces it with the data from the second hash.
I just can't get my head around why this happens.
Here is the code for my class:
package FileHash;
use strict;
use warnings;
use Tie::Hash;
use Data::Dumper;
our @ISA = ("Tie::Hash");
sub TIEHASH {
my ($class, $file) = @_;
my $s = {};
$s->{DATA} = _read($file) || {};
$s->{FILE} = $file;
bless $s, $class;
}
sub STORE { $_[0]->{DATA}{$_[1]} = $_[2] }
sub CLEAR { $_[0]->{DATA} = () }
sub FETCH { $_[0]->{DATA}{$_[1]} }
sub FIRSTKEY { my $a = scalar keys %{$_[0]}; each %{$_[0]->{DATA}} }
sub NEXTKEY { each %{$_[0]->{DATA}} }
sub EXISTS { exists $_[0]->{DATA}{$_[1]} }
sub DELETE { delete $_[0]->{DATA}{$_[1]} }
sub DESTROY { _write ($_[0]) }
# ----- private subs -----
sub _write { # still need to deal with race conditions
my %data = %{$_[0]->{DATA}};
my $file = $_[0]->{FILE} ;
open (FH, "> $file") or die "Can't open $file for FileHash _write:
+$!";
print FH Data::Dumper->Dump([\%data], ['*data']);
close FH or die "Can't close $file for FileHash _write: $!";
}
sub _read { # still need to deal with race conditions
no strict;
my $file = shift;
return undef unless -f $file;
unless (my $ret = do $file) {
warn "couldn't parse $file: $@" if $@;
warn "couldn't do $file: $!" unless defined $ret;
}
return \%data;
}
1;
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