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#
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# ObjectStore.pm
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#
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# Originally Written by Christopher Williams
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#
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# Description
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# -----------
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# An very simple object persistency manager for small scale use.
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# Objects are saved and recovered on demand
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# Objects to be stored in this manager must implement the following interface
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# new(ObjectStore) :
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# store(location) : dump out to location
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# restore(location) : restore from location
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# objects must inherit from StorableObject
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#
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# Interface
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# ---------
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# new(store_directory,[object]) : A new ObjectStore object. An alternative
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# object can be specified with which to
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# construct the stored objects with by
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# supplying the object reference
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# if store_directory begins with "<" - does
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# not attempt to build it if it dosnt exist
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# storeref([object]) : set/return the object store referefnce object
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# (as passed in new)
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# store(oref,@keys) : store an object - each object must have
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# a unique key
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# find(@keys) : find and recover object(s) from the store
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# that match keys. Returned as a list of oref
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# sequence(@keys) : return the sequence number of the object
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# matching the keys
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# An object is assigned a new sequence number
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# with each store.
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# delete(@keys) : Delete the object with the given key
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# alias(\@refofkeys,\@aliaskeys) : attatch another set of keys to objects that
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# match the refofkeys
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# note that these are references to the arrays
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# unalias(@aliaskeys) :remove an alias
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# location() : return the top directory where the store is
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# located
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package ObjectUtilities::ObjectStore;
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require 5.004;
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use Utilities::AddDir;
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use Utilities::HashDB;
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sub new {
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my $class=shift;
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my $dir=shift;
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$self={};
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# do we have an alternative object to instantiate objects with
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if ( @_ ) {
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$self->{storeobject}=shift;
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}
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else {
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$self->{storeobject}=$self;
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}
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bless $self, $class;
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($self->{location}=$dir)=~s/^\<//;
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$self->{admindir}=$self->{location}."/admin";
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if ( $dir=~"^\<" ) {
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}
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else {
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AddDir::adddir($self->{admindir});
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}
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if ( -d $self->{location} ) {
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$self->{storage}=$dir."/objects";
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AddDir::adddir($self->{storage});
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$self->_init();
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}
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else {
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return undef;
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}
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#print "ObjectStore -- $self->{storeobject}\n";
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return $self;
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}
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sub storeref {
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my $self=shift;
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if ( @_ ) {
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$self->{storeobject}=shift;
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}
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return $self->{storeobject};
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}
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sub location {
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my $self=shift;
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return $self->{location};
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}
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sub store {
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my $self=shift;
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my $oref=shift;
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my @keys=@_;
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my $oreftype=ref($oref);
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#print "$self: Storing an object of type : $oreftype\n";
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my $filename=$self->_filename(@keys);
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$oref->store($self->_fullfilename($filename));
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# Update the sequence number to track changes
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my @seqnumbers=$self->{filehash}->getdata("__seq_number",@keys);
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my $seqnumb=((@seqnumbers)?$seqnumbers[0]:-1)+1;
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$self->{filehash}->deletedata("__seq_number",@keys);
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$self->{filehash}->setdata($seqnumb,"__seq_number",@keys);
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$self->{filehash}->deletedata(@keys);
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$self->{filehash}->setdata($filename,@keys); # persistent
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$self->{typehash}->deletedata($filename);
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$self->{typehash}->setdata($oreftype,$filename); # persistent
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$self->{orefhash}->deletedata($filename);
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$self->{orefhash}->setdata($oref,$filename); # transient
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$self->_storedb();
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}
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sub sequence {
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my $self=shift;
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my @keys=@_;
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my @seq=$self->{filehash}->getdata("__seq_number",@keys);
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return (($#seq == 0)?$seq[0]:-1);
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}
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sub find {
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my $self=shift;
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my @keys=@_;
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my @oref=();
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my $oref;
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my @types;
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my $type;
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my @validobjs=();
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my $fh;
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#print "$self: Searching for : @keys\n";
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my @datafiles=$self->{filehash}->getdata(@keys);
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foreach $file ( @datafiles ) {
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@oref=$self->{orefhash}->getdata($file);
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if ( $#oref < 0 ) { # we need to instatniate it
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@types=$self->{typehash}->getdata($file);
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$type=$types[0];
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eval "require $type";
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$oref=$type->new($self->{storeobject});
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$oref->restore($self->_fullfilename($file));
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}
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else {
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$oref=$oref[0];
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}
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push @validobjs, $oref;
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}
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return @validobjs;
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}
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sub alias {
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my $self=shift;
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$self->{filehash}->alias(@_);
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$self->_storedb();
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}
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sub unalias {
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my $self=shift;
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$self->{filehash}->unalias(@_);
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$self->_storedb();
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}
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sub delete {
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my $self=shift;
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my @keys=@_;
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my $filename=$self->_filename(@keys);
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$self->{filehash}->deletedata("__seq_number",@keys);
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$self->{filehash}->deletedata(@keys);
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$self->{typehash}->deletedata($filename);
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$self->{orefhash}->deletedata($filename);
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$self->_storedb();
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print "Deleting ".$self->_fullfilename($filename)."\n";
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unlink $self->_fullfilename($filename);
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}
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#
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# Private routines
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#
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sub _filename {
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my $self=shift;
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my @keys=@_;
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my ($file)=$self->{filehash}->getdata(@keys);
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if ( ! defined $file ) {
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# need to generate a new filename - a random number will do
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srand();
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do {
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$file=int(rand 99999999)+1;
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} until ( ! ( -e $self->_fullfilename($file) ) );
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}
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return $file;
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}
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sub _fullfilename {
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my $self=shift;
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my $file=shift;
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if ( $file!~/^\// ) { # return only full path names
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$file=$self->{storage}."/".$file;
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}
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return $file;
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}
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sub _storedb {
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my $self=shift;
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$self->{filehash}->store($self->{admindir}."/filedb");
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$self->{typehash}->store($self->{admindir}."/typedb");
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}
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sub _restoredb {
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my $self=shift;
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if ( -f $self->{admindir}."/filedb" ) {
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$self->{filehash}->restore($self->{admindir}."/filedb");
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$self->{typehash}->restore($self->{admindir}."/typedb");
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}
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}
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sub _openfile {
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my $self=shift;
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my $filename=shift;
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local $fh=FileHandle->new();
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open ( $fh, $filename) or die "Unable to open $filename\n $!\n";
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return $fh;
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}
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sub _init {
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my $self=shift;
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$self->{filehash}=Utilities::HashDB->new();
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$self->{typehash}=Utilities::HashDB->new();
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$self->{orefhash}=Utilities::HashDB->new();
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$self->_restoredb();
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}
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