1 ;# $Id: Storable.pm,v 1.0.1.13 2001/12/01 13:34:49 ram Exp $
3 ;# Copyright (c) 1995-2000, Raphael Manfredi
5 ;# You may redistribute only under the same terms as Perl 5, as specified
6 ;# in the README file that comes with the distribution.
8 ;# $Log: Storable.pm,v $
9 ;# Revision 1.0.1.13 2001/12/01 13:34:49 ram
10 ;# patch14: avoid requiring Fcntl upfront, useful to embedded runtimes
11 ;# patch14: store_fd() will now correctly autoflush file if needed
13 ;# Revision 1.0.1.12 2001/08/28 21:51:51 ram
14 ;# patch13: fixed truncation race with lock_retrieve() in lock_store()
16 ;# Revision 1.0.1.11 2001/07/01 11:22:14 ram
17 ;# patch12: systematically use "=over 4" for POD linters
18 ;# patch12: updated version number
20 ;# Revision 1.0.1.10 2001/03/15 00:20:25 ram
21 ;# patch11: updated version number
23 ;# Revision 1.0.1.9 2001/02/17 12:37:32 ram
24 ;# patch10: forgot to increase version number at previous patch
26 ;# Revision 1.0.1.8 2001/02/17 12:24:37 ram
27 ;# patch8: fixed incorrect error message
29 ;# Revision 1.0.1.7 2001/01/03 09:39:02 ram
30 ;# patch7: added CAN_FLOCK to determine whether we can flock() or not
32 ;# Revision 1.0.1.6 2000/11/05 17:20:25 ram
33 ;# patch6: increased version number
35 ;# Revision 1.0.1.5 2000/10/26 17:10:18 ram
36 ;# patch5: documented that store() and retrieve() can return undef
37 ;# patch5: added paragraph explaining the auto require for thaw hooks
39 ;# Revision 1.0.1.4 2000/10/23 18:02:57 ram
40 ;# patch4: protected calls to flock() for dos platform
41 ;# patch4: added logcarp emulation if they don't have Log::Agent
43 ;# Revision 1.0.1.3 2000/09/29 19:49:01 ram
44 ;# patch3: updated version number
46 ;# Revision 1.0.1.2 2000/09/28 21:42:51 ram
47 ;# patch2: added lock_store lock_nstore lock_retrieve
49 ;# Revision 1.0.1.1 2000/09/17 16:46:21 ram
50 ;# patch1: documented that doubles are stringified by nstore()
51 ;# patch1: added Salvador Ortiz Garcia in CREDITS section
53 ;# Revision 1.0 2000/09/01 19:40:41 ram
54 ;# Baseline for first official release.
59 package Storable; @ISA = qw(Exporter DynaLoader);
61 @EXPORT = qw(store retrieve);
63 nstore store_fd nstore_fd fd_retrieve
67 lock_store lock_nstore lock_retrieve
71 use vars qw($forgive_me $VERSION);
74 *AUTOLOAD = \&AutoLoader::AUTOLOAD; # Grrr...
77 # Use of Log::Agent is optional
80 eval "use Log::Agent";
82 unless (defined @Log::Agent::EXPORT) {
96 # They might miss :flock in Fcntl
100 if (eval { require Fcntl; 1 } && exists $Fcntl::EXPORT_TAGS{'flock'}) {
101 Fcntl->import(':flock');
113 sub retrieve_fd { &fd_retrieve } # Backward compatibility
116 # Determine whether locking is possible, but only when needed.
122 return $CAN_FLOCK if defined $CAN_FLOCK;
123 require Config; import Config;
125 $Config{'d_flock'} ||
126 $Config{'d_fcntl_can_lock'} ||
130 sub show_file_magic {
133 # To recognize the data files of the Perl module Storable,
134 # the following lines need to be added to the local magic(5) file,
135 # usually either /usr/share/misc/magic or /etc/magic.
136 # Note the couple of unportable lines, consult your operating
137 # system's documentation whether you can use those lines.
139 0 string perl-store perl Storable(v0.6) data
140 >1 byte &01 (network-ordered)
141 0 string pst0 perl Storable(v0.7) data
142 # byte&04 unportable syntax
145 >4 byte &01 (network-ordered)
146 # byte&01 unportable syntax
147 >4 byte&01 =0 (local-ordered)
148 >>6 byte >0 (sizeof int %d)
149 >>7 byte >0 (sizeof long %d)
150 >>8 byte >0 (sizeof ptr %d)
151 >>9 byte >0 (sizeof NV %d)
162 # Store target object hierarchy, identified by a reference to its root.
163 # The stored object tree may later be retrieved to memory via retrieve.
164 # Returns undef if an I/O error occurred, in which case the file is
168 return _store(\&pstore, @_, 0);
174 # Same as store, but in network order.
177 return _store(\&net_pstore, @_, 0);
183 # Same as store, but flock the file first (advisory locking).
186 return _store(\&pstore, @_, 1);
192 # Same as nstore, but flock the file first (advisory locking).
195 return _store(\&net_pstore, @_, 1);
198 # Internal store to file routine
202 my ($file, $use_locking) = @_;
203 logcroak "not a reference" unless ref($self);
204 logcroak "wrong argument number" unless @_ == 2; # No @foo in arglist
207 open(FILE, ">>$file") || logcroak "can't write into $file: $!";
208 unless (&CAN_FLOCK) {
209 logcarp "Storable::lock_store: fcntl/flock emulation broken on $^O";
212 flock(FILE, LOCK_EX) ||
213 logcroak "can't get exclusive lock on $file: $!";
215 # Unlocking will happen when FILE is closed
217 open(FILE, ">$file") || logcroak "can't create $file: $!";
219 binmode FILE; # Archaic systems...
220 my $da = $@; # Don't mess if called from exception handler
222 # Call C routine nstore or pstore, depending on network order
223 eval { $ret = &$xsptr(*FILE, $self) };
224 close(FILE) or $ret = undef;
225 unlink($file) or warn "Can't unlink $file: $!\n" if $@ || !defined $ret;
226 logcroak $@ if $@ =~ s/\.?\n$/,/;
228 return $ret ? $ret : undef;
234 # Same as store, but perform on an already opened file descriptor instead.
235 # Returns undef if an I/O error occurred.
238 return _store_fd(\&pstore, @_);
244 # Same as store_fd, but in network order.
247 my ($self, $file) = @_;
248 return _store_fd(\&net_pstore, @_);
251 # Internal store routine on opened file descriptor
256 logcroak "not a reference" unless ref($self);
257 logcroak "too many arguments" unless @_ == 1; # No @foo in arglist
258 my $fd = fileno($file);
259 logcroak "not a valid file descriptor" unless defined $fd;
260 my $da = $@; # Don't mess if called from exception handler
262 # Call C routine nstore or pstore, depending on network order
263 eval { $ret = &$xsptr($file, $self) };
264 logcroak $@ if $@ =~ s/\.?\n$/,/;
265 local $\; print $file ''; # Autoflush the file if wanted
267 return $ret ? $ret : undef;
273 # Store oject and its hierarchy in memory and return a scalar
274 # containing the result.
277 _freeze(\&mstore, @_);
283 # Same as freeze but in network order.
286 _freeze(\&net_mstore, @_);
289 # Internal freeze routine
293 logcroak "not a reference" unless ref($self);
294 logcroak "too many arguments" unless @_ == 0; # No @foo in arglist
295 my $da = $@; # Don't mess if called from exception handler
297 # Call C routine mstore or net_mstore, depending on network order
298 eval { $ret = &$xsptr($self) };
299 logcroak $@ if $@ =~ s/\.?\n$/,/;
301 return $ret ? $ret : undef;
307 # Retrieve object hierarchy from disk, returning a reference to the root
308 # object of that tree.
317 # Same as retrieve, but with advisory locking.
323 # Internal retrieve routine
325 my ($file, $use_locking) = @_;
327 open(FILE, $file) || logcroak "can't open $file: $!";
328 binmode FILE; # Archaic systems...
330 my $da = $@; # Could be from exception handler
332 unless (&CAN_FLOCK) {
333 logcarp "Storable::lock_store: fcntl/flock emulation broken on $^O";
336 flock(FILE, LOCK_SH) || logcroak "can't get shared lock on $file: $!";
337 # Unlocking will happen when FILE is closed
339 eval { $self = pretrieve(*FILE) }; # Call C routine
341 logcroak $@ if $@ =~ s/\.?\n$/,/;
349 # Same as retrieve, but perform from an already opened file descriptor instead.
353 my $fd = fileno($file);
354 logcroak "not a valid file descriptor" unless defined $fd;
356 my $da = $@; # Could be from exception handler
357 eval { $self = pretrieve($file) }; # Call C routine
358 logcroak $@ if $@ =~ s/\.?\n$/,/;
366 # Recreate objects in memory from an existing frozen image created
367 # by freeze. If the frozen image passed is undef, return undef.
371 return undef unless defined $frozen;
373 my $da = $@; # Could be from exception handler
374 eval { $self = mretrieve($frozen) }; # Call C routine
375 logcroak $@ if $@ =~ s/\.?\n$/,/;
382 Storable - persistency for perl data structures
387 store \%table, 'file';
388 $hashref = retrieve('file');
390 use Storable qw(nstore store_fd nstore_fd freeze thaw dclone);
393 nstore \%table, 'file';
394 $hashref = retrieve('file'); # There is NO nretrieve()
396 # Storing to and retrieving from an already opened file
397 store_fd \@array, \*STDOUT;
398 nstore_fd \%table, \*STDOUT;
399 $aryref = fd_retrieve(\*SOCKET);
400 $hashref = fd_retrieve(\*SOCKET);
402 # Serializing to memory
403 $serialized = freeze \%table;
404 %table_clone = %{ thaw($serialized) };
406 # Deep (recursive) cloning
407 $cloneref = dclone($ref);
410 use Storable qw(lock_store lock_nstore lock_retrieve)
411 lock_store \%table, 'file';
412 lock_nstore \%table, 'file';
413 $hashref = lock_retrieve('file');
417 The Storable package brings persistency to your perl data structures
418 containing SCALAR, ARRAY, HASH or REF objects, i.e. anything that can be
419 convenientely stored to disk and retrieved at a later time.
421 It can be used in the regular procedural way by calling C<store> with
422 a reference to the object to be stored, along with the file name where
423 the image should be written.
424 The routine returns C<undef> for I/O problems or other internal error,
425 a true value otherwise. Serious errors are propagated as a C<die> exception.
427 To retrieve data stored to disk, use C<retrieve> with a file name,
428 and the objects stored into that file are recreated into memory for you,
429 a I<reference> to the root object being returned. In case an I/O error
430 occurs while reading, C<undef> is returned instead. Other serious
431 errors are propagated via C<die>.
433 Since storage is performed recursively, you might want to stuff references
434 to objects that share a lot of common data into a single array or hash
435 table, and then store that object. That way, when you retrieve back the
436 whole thing, the objects will continue to share what they originally shared.
438 At the cost of a slight header overhead, you may store to an already
439 opened file descriptor using the C<store_fd> routine, and retrieve
440 from a file via C<fd_retrieve>. Those names aren't imported by default,
441 so you will have to do that explicitely if you need those routines.
442 The file descriptor you supply must be already opened, for read
443 if you're going to retrieve and for write if you wish to store.
445 store_fd(\%table, *STDOUT) || die "can't store to stdout\n";
446 $hashref = fd_retrieve(*STDIN);
448 You can also store data in network order to allow easy sharing across
449 multiple platforms, or when storing on a socket known to be remotely
450 connected. The routines to call have an initial C<n> prefix for I<network>,
451 as in C<nstore> and C<nstore_fd>. At retrieval time, your data will be
452 correctly restored so you don't have to know whether you're restoring
453 from native or network ordered data. Double values are stored stringified
454 to ensure portability as well, at the slight risk of loosing some precision
455 in the last decimals.
457 When using C<fd_retrieve>, objects are retrieved in sequence, one
458 object (i.e. one recursive tree) per associated C<store_fd>.
460 If you're more from the object-oriented camp, you can inherit from
461 Storable and directly store your objects by invoking C<store> as
462 a method. The fact that the root of the to-be-stored tree is a
463 blessed reference (i.e. an object) is special-cased so that the
464 retrieve does not provide a reference to that object but rather the
465 blessed object reference itself. (Otherwise, you'd get a reference
466 to that blessed object).
470 The Storable engine can also store data into a Perl scalar instead, to
471 later retrieve them. This is mainly used to freeze a complex structure in
472 some safe compact memory place (where it can possibly be sent to another
473 process via some IPC, since freezing the structure also serializes it in
474 effect). Later on, and maybe somewhere else, you can thaw the Perl scalar
475 out and recreate the original complex structure in memory.
477 Surprisingly, the routines to be called are named C<freeze> and C<thaw>.
478 If you wish to send out the frozen scalar to another machine, use
479 C<nfreeze> instead to get a portable image.
481 Note that freezing an object structure and immediately thawing it
482 actually achieves a deep cloning of that structure:
484 dclone(.) = thaw(freeze(.))
486 Storable provides you with a C<dclone> interface which does not create
487 that intermediary scalar but instead freezes the structure in some
488 internal memory space and then immediatly thaws it out.
490 =head1 ADVISORY LOCKING
492 The C<lock_store> and C<lock_nstore> routine are equivalent to C<store>
493 and C<nstore>, only they get an exclusive lock on the file before
494 writing. Likewise, C<lock_retrieve> performs as C<retrieve>, but also
495 gets a shared lock on the file before reading.
497 Like with any advisory locking scheme, the protection only works if
498 you systematically use C<lock_store> and C<lock_retrieve>. If one
499 side of your application uses C<store> whilst the other uses C<lock_retrieve>,
500 you will get no protection at all.
502 The internal advisory locking is implemented using Perl's flock() routine.
503 If your system does not support any form of flock(), or if you share
504 your files across NFS, you might wish to use other forms of locking by
505 using modules like LockFile::Simple which lock a file using a filesystem
506 entry, instead of locking the file descriptor.
510 The heart of Storable is written in C for decent speed. Extra low-level
511 optimization have been made when manipulating perl internals, to
512 sacrifice encapsulation for the benefit of a greater speed.
514 =head1 CANONICAL REPRESENTATION
516 Normally Storable stores elements of hashes in the order they are
517 stored internally by Perl, i.e. pseudo-randomly. If you set
518 C<$Storable::canonical> to some C<TRUE> value, Storable will store
519 hashes with the elements sorted by their key. This allows you to
520 compare data structures by comparing their frozen representations (or
521 even the compressed frozen representations), which can be useful for
522 creating lookup tables for complicated queries.
524 Canonical order does not imply network order, those are two orthogonal
527 =head1 ERROR REPORTING
529 Storable uses the "exception" paradigm, in that it does not try to workaround
530 failures: if something bad happens, an exception is generated from the
531 caller's perspective (see L<Carp> and C<croak()>). Use eval {} to trap
534 When Storable croaks, it tries to report the error via the C<logcroak()>
535 routine from the C<Log::Agent> package, if it is available.
537 Normal errors are reported by having store() or retrieve() return C<undef>.
538 Such errors are usually I/O errors (or truncated stream errors at retrieval).
544 Any class may define hooks that will be called during the serialization
545 and deserialization process on objects that are instances of that class.
546 Those hooks can redefine the way serialization is performed (and therefore,
547 how the symetrical deserialization should be conducted).
549 Since we said earlier:
551 dclone(.) = thaw(freeze(.))
553 everything we say about hooks should also hold for deep cloning. However,
554 hooks get to know whether the operation is a mere serialization, or a cloning.
556 Therefore, when serializing hooks are involved,
558 dclone(.) <> thaw(freeze(.))
560 Well, you could keep them in sync, but there's no guarantee it will always
561 hold on classes somebody else wrote. Besides, there is little to gain in
562 doing so: a serializing hook could only keep one attribute of an object,
563 which is probably not what should happen during a deep cloning of that
566 Here is the hooking interface:
570 =item C<STORABLE_freeze> I<obj>, I<cloning>
572 The serializing hook, called on the object during serialization. It can be
573 inherited, or defined in the class itself, like any other method.
575 Arguments: I<obj> is the object to serialize, I<cloning> is a flag indicating
576 whether we're in a dclone() or a regular serialization via store() or freeze().
578 Returned value: A LIST C<($serialized, $ref1, $ref2, ...)> where $serialized
579 is the serialized form to be used, and the optional $ref1, $ref2, etc... are
580 extra references that you wish to let the Storable engine serialize.
582 At deserialization time, you will be given back the same LIST, but all the
583 extra references will be pointing into the deserialized structure.
585 The B<first time> the hook is hit in a serialization flow, you may have it
586 return an empty list. That will signal the Storable engine to further
587 discard that hook for this class and to therefore revert to the default
588 serialization of the underlying Perl data. The hook will again be normally
589 processed in the next serialization.
591 Unless you know better, serializing hook should always say:
593 sub STORABLE_freeze {
594 my ($self, $cloning) = @_;
595 return if $cloning; # Regular default serialization
599 in order to keep reasonable dclone() semantics.
601 =item C<STORABLE_thaw> I<obj>, I<cloning>, I<serialized>, ...
603 The deserializing hook called on the object during deserialization.
604 But wait. If we're deserializing, there's no object yet... right?
606 Wrong: the Storable engine creates an empty one for you. If you know Eiffel,
607 you can view C<STORABLE_thaw> as an alternate creation routine.
609 This means the hook can be inherited like any other method, and that
610 I<obj> is your blessed reference for this particular instance.
612 The other arguments should look familiar if you know C<STORABLE_freeze>:
613 I<cloning> is true when we're part of a deep clone operation, I<serialized>
614 is the serialized string you returned to the engine in C<STORABLE_freeze>,
615 and there may be an optional list of references, in the same order you gave
616 them at serialization time, pointing to the deserialized objects (which
617 have been processed courtesy of the Storable engine).
619 When the Storable engine does not find any C<STORABLE_thaw> hook routine,
620 it tries to load the class by requiring the package dynamically (using
621 the blessed package name), and then re-attempts the lookup. If at that
622 time the hook cannot be located, the engine croaks. Note that this mechanism
623 will fail if you define several classes in the same file, but perlmod(1)
626 It is up to you to use these information to populate I<obj> the way you want.
628 Returned value: none.
634 Predicates are not exportable. They must be called by explicitely prefixing
635 them with the Storable package name.
639 =item C<Storable::last_op_in_netorder>
641 The C<Storable::last_op_in_netorder()> predicate will tell you whether
642 network order was used in the last store or retrieve operation. If you
643 don't know how to use this, just forget about it.
645 =item C<Storable::is_storing>
647 Returns true if within a store operation (via STORABLE_freeze hook).
649 =item C<Storable::is_retrieving>
651 Returns true if within a retrieve operation, (via STORABLE_thaw hook).
657 With hooks comes the ability to recurse back to the Storable engine. Indeed,
658 hooks are regular Perl code, and Storable is convenient when it comes to
659 serialize and deserialize things, so why not use it to handle the
660 serialization string?
662 There are a few things you need to know however:
668 You can create endless loops if the things you serialize via freeze()
669 (for instance) point back to the object we're trying to serialize in the hook.
673 Shared references among objects will not stay shared: if we're serializing
674 the list of object [A, C] where both object A and C refer to the SAME object
675 B, and if there is a serializing hook in A that says freeze(B), then when
676 deserializing, we'll get [A', C'] where A' refers to B', but C' refers to D,
677 a deep clone of B'. The topology was not preserved.
681 That's why C<STORABLE_freeze> lets you provide a list of references
682 to serialize. The engine guarantees that those will be serialized in the
683 same context as the other objects, and therefore that shared objects will
686 In the above [A, C] example, the C<STORABLE_freeze> hook could return:
688 ("something", $self->{B})
690 and the B part would be serialized by the engine. In C<STORABLE_thaw>, you
691 would get back the reference to the B' object, deserialized for you.
693 Therefore, recursion should normally be avoided, but is nonetheless supported.
697 There is a new Clone module available on CPAN which implements deep cloning
698 natively, i.e. without freezing to memory and thawing the result. It is
699 aimed to replace Storable's dclone() some day. However, it does not currently
700 support Storable hooks to redefine the way deep cloning is performed.
702 =head1 Storable magic
704 Yes, there's a lot of that :-) But more precisely, in UNIX systems
705 there's a utility called C<file>, which recognizes data files based on
706 their contents (usually their first few bytes). For this to work,
707 a certain file called "magic" needs to taught about the "signature"
708 of the data. Where that configuration file lives depends on the UNIX
709 flavour, often it's something like F</usr/share/misc/magic> or
710 F</etc/magic>. Your system administrator needs to do the updating.
711 The necessary signature information is output to stdout by
712 invoking Storable::show_file_magic().
716 Here are some code samples showing a possible usage of Storable:
718 use Storable qw(store retrieve freeze thaw dclone);
720 %color = ('Blue' => 0.1, 'Red' => 0.8, 'Black' => 0, 'White' => 1);
722 store(\%color, '/tmp/colors') or die "Can't store %a in /tmp/colors!\n";
724 $colref = retrieve('/tmp/colors');
725 die "Unable to retrieve from /tmp/colors!\n" unless defined $colref;
726 printf "Blue is still %lf\n", $colref->{'Blue'};
728 $colref2 = dclone(\%color);
730 $str = freeze(\%color);
731 printf "Serialization of %%color is %d bytes long.\n", length($str);
732 $colref3 = thaw($str);
734 which prints (on my machine):
736 Blue is still 0.100000
737 Serialization of %color is 102 bytes long.
741 If you're using references as keys within your hash tables, you're bound
742 to disapointment when retrieving your data. Indeed, Perl stringifies
743 references used as hash table keys. If you later wish to access the
744 items via another reference stringification (i.e. using the same
745 reference that was used for the key originally to record the value into
746 the hash table), it will work because both references stringify to the
749 It won't work across a C<store> and C<retrieve> operations however, because
750 the addresses in the retrieved objects, which are part of the stringified
751 references, will probably differ from the original addresses. The
752 topology of your structure is preserved, but not hidden semantics
755 On platforms where it matters, be sure to call C<binmode()> on the
756 descriptors that you pass to Storable functions.
758 Storing data canonically that contains large hashes can be
759 significantly slower than storing the same data normally, as
760 temprorary arrays to hold the keys for each hash have to be allocated,
761 populated, sorted and freed. Some tests have shown a halving of the
762 speed of storing -- the exact penalty will depend on the complexity of
763 your data. There is no slowdown on retrieval.
767 You can't store GLOB, CODE, FORMLINE, etc... If you can define
768 semantics for those operations, feel free to enhance Storable so that
769 it can deal with them.
771 The store functions will C<croak> if they run into such references
772 unless you set C<$Storable::forgive_me> to some C<TRUE> value. In that
773 case, the fatal message is turned in a warning and some
774 meaningless string is stored instead.
776 Setting C<$Storable::canonical> may not yield frozen strings that
777 compare equal due to possible stringification of numbers. When the
778 string version of a scalar exists, it is the form stored, therefore
779 if you happen to use your numbers as strings between two freezing
780 operations on the same data structures, you will get different
783 When storing doubles in network order, their value is stored as text.
784 However, you should also not expect non-numeric floating-point values
785 such as infinity and "not a number" to pass successfully through a
786 nstore()/retrieve() pair.
788 As Storable neither knows nor cares about character sets (although it
789 does know that characters may be more than eight bits wide), any difference
790 in the interpretation of character codes between a host and a target
791 system is your problem. In particular, if host and target use different
792 code points to represent the characters used in the text representation
793 of floating-point numbers, you will not be able be able to exchange
794 floating-point data, even with nstore().
798 Thank you to (in chronological order):
800 Jarkko Hietaniemi <jhi@iki.fi>
801 Ulrich Pfeifer <pfeifer@charly.informatik.uni-dortmund.de>
802 Benjamin A. Holzman <bah@ecnvantage.com>
803 Andrew Ford <A.Ford@ford-mason.co.uk>
804 Gisle Aas <gisle@aas.no>
805 Jeff Gresham <gresham_jeffrey@jpmorgan.com>
806 Murray Nesbitt <murray@activestate.com>
807 Marc Lehmann <pcg@opengroup.org>
808 Justin Banks <justinb@wamnet.com>
809 Jarkko Hietaniemi <jhi@iki.fi> (AGAIN, as perl 5.7.0 Pumpkin!)
810 Salvador Ortiz Garcia <sog@msg.com.mx>
811 Dominic Dunlop <domo@computer.org>
812 Erik Haugan <erik@solbors.no>
814 for their bug reports, suggestions and contributions.
816 Benjamin Holzman contributed the tied variable support, Andrew Ford
817 contributed the canonical order for hashes, and Gisle Aas fixed
818 a few misunderstandings of mine regarding the Perl internals,
819 and optimized the emission of "tags" in the output streams by
820 simply counting the objects instead of tagging them (leading to
821 a binary incompatibility for the Storable image starting at version
822 0.6--older images are of course still properly understood).
823 Murray Nesbitt made Storable thread-safe. Marc Lehmann added overloading
824 and reference to tied items support.
828 There is a Japanese translation of this man page available at
829 http://member.nifty.ne.jp/hippo2000/perltips/storable.htm ,
830 courtesy of Kawai, Takanori <kawai@nippon-rad.co.jp>.
834 Raphael Manfredi F<E<lt>Raphael_Manfredi@pobox.comE<gt>>