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1 | ;# $Id: Storable.pm,v 1.0 2000/09/01 19:40:41 ram Exp $ |
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2 | ;# |
3 | ;# Copyright (c) 1995-2000, Raphael Manfredi |
4 | ;# |
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5 | ;# You may redistribute only under the same terms as Perl 5, as specified |
6 | ;# in the README file that comes with the distribution. |
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7 | ;# |
8 | ;# $Log: Storable.pm,v $ |
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9 | ;# Revision 1.0 2000/09/01 19:40:41 ram |
10 | ;# Baseline for first official release. |
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11 | ;# |
12 | |
13 | require DynaLoader; |
14 | require Exporter; |
15 | package Storable; @ISA = qw(Exporter DynaLoader); |
16 | |
17 | @EXPORT = qw(store retrieve); |
18 | @EXPORT_OK = qw( |
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19 | nstore store_fd nstore_fd fd_retrieve |
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20 | freeze nfreeze thaw |
21 | dclone |
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22 | retrieve_fd |
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23 | ); |
24 | |
25 | use AutoLoader; |
26 | use vars qw($forgive_me $VERSION); |
27 | |
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28 | $VERSION = '1.000'; |
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29 | *AUTOLOAD = \&AutoLoader::AUTOLOAD; # Grrr... |
30 | |
31 | # |
32 | # Use of Log::Agent is optional |
33 | # |
34 | |
35 | eval "use Log::Agent"; |
36 | |
37 | unless (defined @Log::Agent::EXPORT) { |
38 | eval q{ |
39 | sub logcroak { |
40 | require Carp; |
41 | Carp::croak(@_); |
42 | } |
43 | }; |
44 | } |
45 | |
46 | sub logcroak; |
47 | |
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48 | sub retrieve_fd { &fd_retrieve } # Backward compatibility |
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49 | |
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50 | bootstrap Storable; |
51 | 1; |
52 | __END__ |
53 | |
54 | # |
55 | # store |
56 | # |
57 | # Store target object hierarchy, identified by a reference to its root. |
58 | # The stored object tree may later be retrieved to memory via retrieve. |
59 | # Returns undef if an I/O error occurred, in which case the file is |
60 | # removed. |
61 | # |
62 | sub store { |
63 | return _store(\&pstore, @_); |
64 | } |
65 | |
66 | # |
67 | # nstore |
68 | # |
69 | # Same as store, but in network order. |
70 | # |
71 | sub nstore { |
72 | return _store(\&net_pstore, @_); |
73 | } |
74 | |
75 | # Internal store to file routine |
76 | sub _store { |
77 | my $xsptr = shift; |
78 | my $self = shift; |
79 | my ($file) = @_; |
80 | logcroak "not a reference" unless ref($self); |
81 | logcroak "too many arguments" unless @_ == 1; # No @foo in arglist |
82 | local *FILE; |
83 | open(FILE, ">$file") || logcroak "can't create $file: $!"; |
84 | binmode FILE; # Archaic systems... |
85 | my $da = $@; # Don't mess if called from exception handler |
86 | my $ret; |
87 | # Call C routine nstore or pstore, depending on network order |
88 | eval { $ret = &$xsptr(*FILE, $self) }; |
89 | close(FILE) or $ret = undef; |
90 | unlink($file) or warn "Can't unlink $file: $!\n" if $@ || !defined $ret; |
91 | logcroak $@ if $@ =~ s/\.?\n$/,/; |
92 | $@ = $da; |
93 | return $ret ? $ret : undef; |
94 | } |
95 | |
96 | # |
97 | # store_fd |
98 | # |
99 | # Same as store, but perform on an already opened file descriptor instead. |
100 | # Returns undef if an I/O error occurred. |
101 | # |
102 | sub store_fd { |
103 | return _store_fd(\&pstore, @_); |
104 | } |
105 | |
106 | # |
107 | # nstore_fd |
108 | # |
109 | # Same as store_fd, but in network order. |
110 | # |
111 | sub nstore_fd { |
112 | my ($self, $file) = @_; |
113 | return _store_fd(\&net_pstore, @_); |
114 | } |
115 | |
116 | # Internal store routine on opened file descriptor |
117 | sub _store_fd { |
118 | my $xsptr = shift; |
119 | my $self = shift; |
120 | my ($file) = @_; |
121 | logcroak "not a reference" unless ref($self); |
122 | logcroak "too many arguments" unless @_ == 1; # No @foo in arglist |
123 | my $fd = fileno($file); |
124 | logcroak "not a valid file descriptor" unless defined $fd; |
125 | my $da = $@; # Don't mess if called from exception handler |
126 | my $ret; |
127 | # Call C routine nstore or pstore, depending on network order |
128 | eval { $ret = &$xsptr($file, $self) }; |
129 | logcroak $@ if $@ =~ s/\.?\n$/,/; |
130 | $@ = $da; |
131 | return $ret ? $ret : undef; |
132 | } |
133 | |
134 | # |
135 | # freeze |
136 | # |
137 | # Store oject and its hierarchy in memory and return a scalar |
138 | # containing the result. |
139 | # |
140 | sub freeze { |
141 | _freeze(\&mstore, @_); |
142 | } |
143 | |
144 | # |
145 | # nfreeze |
146 | # |
147 | # Same as freeze but in network order. |
148 | # |
149 | sub nfreeze { |
150 | _freeze(\&net_mstore, @_); |
151 | } |
152 | |
153 | # Internal freeze routine |
154 | sub _freeze { |
155 | my $xsptr = shift; |
156 | my $self = shift; |
157 | logcroak "not a reference" unless ref($self); |
158 | logcroak "too many arguments" unless @_ == 0; # No @foo in arglist |
159 | my $da = $@; # Don't mess if called from exception handler |
160 | my $ret; |
161 | # Call C routine mstore or net_mstore, depending on network order |
162 | eval { $ret = &$xsptr($self) }; |
163 | logcroak $@ if $@ =~ s/\.?\n$/,/; |
164 | $@ = $da; |
165 | return $ret ? $ret : undef; |
166 | } |
167 | |
168 | # |
169 | # retrieve |
170 | # |
171 | # Retrieve object hierarchy from disk, returning a reference to the root |
172 | # object of that tree. |
173 | # |
174 | sub retrieve { |
175 | my ($file) = @_; |
176 | local *FILE; |
177 | open(FILE, "$file") || logcroak "can't open $file: $!"; |
178 | binmode FILE; # Archaic systems... |
179 | my $self; |
180 | my $da = $@; # Could be from exception handler |
181 | eval { $self = pretrieve(*FILE) }; # Call C routine |
182 | close(FILE); |
183 | logcroak $@ if $@ =~ s/\.?\n$/,/; |
184 | $@ = $da; |
185 | return $self; |
186 | } |
187 | |
188 | # |
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189 | # fd_retrieve |
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190 | # |
191 | # Same as retrieve, but perform from an already opened file descriptor instead. |
192 | # |
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193 | sub fd_retrieve { |
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194 | my ($file) = @_; |
195 | my $fd = fileno($file); |
196 | logcroak "not a valid file descriptor" unless defined $fd; |
197 | my $self; |
198 | my $da = $@; # Could be from exception handler |
199 | eval { $self = pretrieve($file) }; # Call C routine |
200 | logcroak $@ if $@ =~ s/\.?\n$/,/; |
201 | $@ = $da; |
202 | return $self; |
203 | } |
204 | |
205 | # |
206 | # thaw |
207 | # |
208 | # Recreate objects in memory from an existing frozen image created |
209 | # by freeze. If the frozen image passed is undef, return undef. |
210 | # |
211 | sub thaw { |
212 | my ($frozen) = @_; |
213 | return undef unless defined $frozen; |
214 | my $self; |
215 | my $da = $@; # Could be from exception handler |
216 | eval { $self = mretrieve($frozen) }; # Call C routine |
217 | logcroak $@ if $@ =~ s/\.?\n$/,/; |
218 | $@ = $da; |
219 | return $self; |
220 | } |
221 | |
222 | =head1 NAME |
223 | |
224 | Storable - persistency for perl data structures |
225 | |
226 | =head1 SYNOPSIS |
227 | |
228 | use Storable; |
229 | store \%table, 'file'; |
230 | $hashref = retrieve('file'); |
231 | |
232 | use Storable qw(nstore store_fd nstore_fd freeze thaw dclone); |
233 | |
234 | # Network order |
235 | nstore \%table, 'file'; |
236 | $hashref = retrieve('file'); # There is NO nretrieve() |
237 | |
238 | # Storing to and retrieving from an already opened file |
239 | store_fd \@array, \*STDOUT; |
240 | nstore_fd \%table, \*STDOUT; |
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241 | $aryref = fd_retrieve(\*SOCKET); |
242 | $hashref = fd_retrieve(\*SOCKET); |
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243 | |
244 | # Serializing to memory |
245 | $serialized = freeze \%table; |
246 | %table_clone = %{ thaw($serialized) }; |
247 | |
248 | # Deep (recursive) cloning |
249 | $cloneref = dclone($ref); |
250 | |
251 | =head1 DESCRIPTION |
252 | |
253 | The Storable package brings persistency to your perl data structures |
254 | containing SCALAR, ARRAY, HASH or REF objects, i.e. anything that can be |
255 | convenientely stored to disk and retrieved at a later time. |
256 | |
257 | It can be used in the regular procedural way by calling C<store> with |
258 | a reference to the object to be stored, along with the file name where |
259 | the image should be written. |
260 | The routine returns C<undef> for I/O problems or other internal error, |
261 | a true value otherwise. Serious errors are propagated as a C<die> exception. |
262 | |
263 | To retrieve data stored to disk, use C<retrieve> with a file name, |
264 | and the objects stored into that file are recreated into memory for you, |
265 | a I<reference> to the root object being returned. In case an I/O error |
266 | occurs while reading, C<undef> is returned instead. Other serious |
267 | errors are propagated via C<die>. |
268 | |
269 | Since storage is performed recursively, you might want to stuff references |
270 | to objects that share a lot of common data into a single array or hash |
271 | table, and then store that object. That way, when you retrieve back the |
272 | whole thing, the objects will continue to share what they originally shared. |
273 | |
274 | At the cost of a slight header overhead, you may store to an already |
275 | opened file descriptor using the C<store_fd> routine, and retrieve |
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276 | from a file via C<fd_retrieve>. Those names aren't imported by default, |
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277 | so you will have to do that explicitely if you need those routines. |
278 | The file descriptor you supply must be already opened, for read |
279 | if you're going to retrieve and for write if you wish to store. |
280 | |
281 | store_fd(\%table, *STDOUT) || die "can't store to stdout\n"; |
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282 | $hashref = fd_retrieve(*STDIN); |
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283 | |
284 | You can also store data in network order to allow easy sharing across |
285 | multiple platforms, or when storing on a socket known to be remotely |
286 | connected. The routines to call have an initial C<n> prefix for I<network>, |
287 | as in C<nstore> and C<nstore_fd>. At retrieval time, your data will be |
288 | correctly restored so you don't have to know whether you're restoring |
289 | from native or network ordered data. |
290 | |
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291 | When using C<fd_retrieve>, objects are retrieved in sequence, one |
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292 | object (i.e. one recursive tree) per associated C<store_fd>. |
293 | |
294 | If you're more from the object-oriented camp, you can inherit from |
295 | Storable and directly store your objects by invoking C<store> as |
296 | a method. The fact that the root of the to-be-stored tree is a |
297 | blessed reference (i.e. an object) is special-cased so that the |
298 | retrieve does not provide a reference to that object but rather the |
299 | blessed object reference itself. (Otherwise, you'd get a reference |
300 | to that blessed object). |
301 | |
302 | =head1 MEMORY STORE |
303 | |
304 | The Storable engine can also store data into a Perl scalar instead, to |
305 | later retrieve them. This is mainly used to freeze a complex structure in |
306 | some safe compact memory place (where it can possibly be sent to another |
307 | process via some IPC, since freezing the structure also serializes it in |
308 | effect). Later on, and maybe somewhere else, you can thaw the Perl scalar |
309 | out and recreate the original complex structure in memory. |
310 | |
311 | Surprisingly, the routines to be called are named C<freeze> and C<thaw>. |
312 | If you wish to send out the frozen scalar to another machine, use |
313 | C<nfreeze> instead to get a portable image. |
314 | |
315 | Note that freezing an object structure and immediately thawing it |
316 | actually achieves a deep cloning of that structure: |
317 | |
318 | dclone(.) = thaw(freeze(.)) |
319 | |
320 | Storable provides you with a C<dclone> interface which does not create |
321 | that intermediary scalar but instead freezes the structure in some |
322 | internal memory space and then immediatly thaws it out. |
323 | |
324 | =head1 SPEED |
325 | |
326 | The heart of Storable is written in C for decent speed. Extra low-level |
327 | optimization have been made when manipulating perl internals, to |
328 | sacrifice encapsulation for the benefit of a greater speed. |
329 | |
330 | =head1 CANONICAL REPRESENTATION |
331 | |
332 | Normally Storable stores elements of hashes in the order they are |
333 | stored internally by Perl, i.e. pseudo-randomly. If you set |
334 | C<$Storable::canonical> to some C<TRUE> value, Storable will store |
335 | hashes with the elements sorted by their key. This allows you to |
336 | compare data structures by comparing their frozen representations (or |
337 | even the compressed frozen representations), which can be useful for |
338 | creating lookup tables for complicated queries. |
339 | |
340 | Canonical order does not imply network order, those are two orthogonal |
341 | settings. |
342 | |
343 | =head1 ERROR REPORTING |
344 | |
345 | Storable uses the "exception" paradigm, in that it does not try to workaround |
346 | failures: if something bad happens, an exception is generated from the |
347 | caller's perspective (see L<Carp> and C<croak()>). Use eval {} to trap |
348 | those exceptions. |
349 | |
350 | When Storable croaks, it tries to report the error via the C<logcroak()> |
351 | routine from the C<Log::Agent> package, if it is available. |
352 | |
353 | =head1 WIZARDS ONLY |
354 | |
355 | =head2 Hooks |
356 | |
357 | Any class may define hooks that will be called during the serialization |
358 | and deserialization process on objects that are instances of that class. |
359 | Those hooks can redefine the way serialization is performed (and therefore, |
360 | how the symetrical deserialization should be conducted). |
361 | |
362 | Since we said earlier: |
363 | |
364 | dclone(.) = thaw(freeze(.)) |
365 | |
366 | everything we say about hooks should also hold for deep cloning. However, |
367 | hooks get to know whether the operation is a mere serialization, or a cloning. |
368 | |
369 | Therefore, when serializing hooks are involved, |
370 | |
371 | dclone(.) <> thaw(freeze(.)) |
372 | |
373 | Well, you could keep them in sync, but there's no guarantee it will always |
374 | hold on classes somebody else wrote. Besides, there is little to gain in |
375 | doing so: a serializing hook could only keep one attribute of an object, |
376 | which is probably not what should happen during a deep cloning of that |
377 | same object. |
378 | |
379 | Here is the hooking interface: |
380 | |
381 | =over |
382 | |
383 | =item C<STORABLE_freeze> I<obj>, I<cloning> |
384 | |
385 | The serializing hook, called on the object during serialization. It can be |
386 | inherited, or defined in the class itself, like any other method. |
387 | |
388 | Arguments: I<obj> is the object to serialize, I<cloning> is a flag indicating |
389 | whether we're in a dclone() or a regular serialization via store() or freeze(). |
390 | |
391 | Returned value: A LIST C<($serialized, $ref1, $ref2, ...)> where $serialized |
392 | is the serialized form to be used, and the optional $ref1, $ref2, etc... are |
393 | extra references that you wish to let the Storable engine serialize. |
394 | |
395 | At deserialization time, you will be given back the same LIST, but all the |
396 | extra references will be pointing into the deserialized structure. |
397 | |
398 | The B<first time> the hook is hit in a serialization flow, you may have it |
399 | return an empty list. That will signal the Storable engine to further |
400 | discard that hook for this class and to therefore revert to the default |
401 | serialization of the underlying Perl data. The hook will again be normally |
402 | processed in the next serialization. |
403 | |
404 | Unless you know better, serializing hook should always say: |
405 | |
406 | sub STORABLE_freeze { |
407 | my ($self, $cloning) = @_; |
408 | return if $cloning; # Regular default serialization |
409 | .... |
410 | } |
411 | |
412 | in order to keep reasonable dclone() semantics. |
413 | |
414 | =item C<STORABLE_thaw> I<obj>, I<cloning>, I<serialized>, ... |
415 | |
416 | The deserializing hook called on the object during deserialization. |
417 | But wait. If we're deserializing, there's no object yet... right? |
418 | |
419 | Wrong: the Storable engine creates an empty one for you. If you know Eiffel, |
420 | you can view C<STORABLE_thaw> as an alternate creation routine. |
421 | |
422 | This means the hook can be inherited like any other method, and that |
423 | I<obj> is your blessed reference for this particular instance. |
424 | |
425 | The other arguments should look familiar if you know C<STORABLE_freeze>: |
426 | I<cloning> is true when we're part of a deep clone operation, I<serialized> |
427 | is the serialized string you returned to the engine in C<STORABLE_freeze>, |
428 | and there may be an optional list of references, in the same order you gave |
429 | them at serialization time, pointing to the deserialized objects (which |
430 | have been processed courtesy of the Storable engine). |
431 | |
432 | It is up to you to use these information to populate I<obj> the way you want. |
433 | |
434 | Returned value: none. |
435 | |
436 | =back |
437 | |
438 | =head2 Predicates |
439 | |
440 | Predicates are not exportable. They must be called by explicitely prefixing |
441 | them with the Storable package name. |
442 | |
443 | =over |
444 | |
445 | =item C<Storable::last_op_in_netorder> |
446 | |
447 | The C<Storable::last_op_in_netorder()> predicate will tell you whether |
448 | network order was used in the last store or retrieve operation. If you |
449 | don't know how to use this, just forget about it. |
450 | |
451 | =item C<Storable::is_storing> |
452 | |
453 | Returns true if within a store operation (via STORABLE_freeze hook). |
454 | |
455 | =item C<Storable::is_retrieving> |
456 | |
457 | Returns true if within a retrieve operation, (via STORABLE_thaw hook). |
458 | |
459 | =back |
460 | |
461 | =head2 Recursion |
462 | |
463 | With hooks comes the ability to recurse back to the Storable engine. Indeed, |
464 | hooks are regular Perl code, and Storable is convenient when it comes to |
465 | serialize and deserialize things, so why not use it to handle the |
466 | serialization string? |
467 | |
468 | There are a few things you need to know however: |
469 | |
470 | =over |
471 | |
472 | =item * |
473 | |
474 | You can create endless loops if the things you serialize via freeze() |
475 | (for instance) point back to the object we're trying to serialize in the hook. |
476 | |
477 | =item * |
478 | |
479 | Shared references among objects will not stay shared: if we're serializing |
480 | the list of object [A, C] where both object A and C refer to the SAME object |
481 | B, and if there is a serializing hook in A that says freeze(B), then when |
482 | deserializing, we'll get [A', C'] where A' refers to B', but C' refers to D, |
483 | a deep clone of B'. The topology was not preserved. |
484 | |
485 | =back |
486 | |
487 | That's why C<STORABLE_freeze> lets you provide a list of references |
488 | to serialize. The engine guarantees that those will be serialized in the |
489 | same context as the other objects, and therefore that shared objects will |
490 | stay shared. |
491 | |
492 | In the above [A, C] example, the C<STORABLE_freeze> hook could return: |
493 | |
494 | ("something", $self->{B}) |
495 | |
496 | and the B part would be serialized by the engine. In C<STORABLE_thaw>, you |
497 | would get back the reference to the B' object, deserialized for you. |
498 | |
499 | Therefore, recursion should normally be avoided, but is nonetheless supported. |
500 | |
501 | =head2 Deep Cloning |
502 | |
503 | There is a new Clone module available on CPAN which implements deep cloning |
504 | natively, i.e. without freezing to memory and thawing the result. It is |
505 | aimed to replace Storable's dclone() some day. However, it does not currently |
506 | support Storable hooks to redefine the way deep cloning is performed. |
507 | |
508 | =head1 EXAMPLES |
509 | |
510 | Here are some code samples showing a possible usage of Storable: |
511 | |
512 | use Storable qw(store retrieve freeze thaw dclone); |
513 | |
514 | %color = ('Blue' => 0.1, 'Red' => 0.8, 'Black' => 0, 'White' => 1); |
515 | |
516 | store(\%color, '/tmp/colors') or die "Can't store %a in /tmp/colors!\n"; |
517 | |
518 | $colref = retrieve('/tmp/colors'); |
519 | die "Unable to retrieve from /tmp/colors!\n" unless defined $colref; |
520 | printf "Blue is still %lf\n", $colref->{'Blue'}; |
521 | |
522 | $colref2 = dclone(\%color); |
523 | |
524 | $str = freeze(\%color); |
525 | printf "Serialization of %%color is %d bytes long.\n", length($str); |
526 | $colref3 = thaw($str); |
527 | |
528 | which prints (on my machine): |
529 | |
530 | Blue is still 0.100000 |
531 | Serialization of %color is 102 bytes long. |
532 | |
533 | =head1 WARNING |
534 | |
535 | If you're using references as keys within your hash tables, you're bound |
536 | to disapointment when retrieving your data. Indeed, Perl stringifies |
537 | references used as hash table keys. If you later wish to access the |
538 | items via another reference stringification (i.e. using the same |
539 | reference that was used for the key originally to record the value into |
540 | the hash table), it will work because both references stringify to the |
541 | same string. |
542 | |
543 | It won't work across a C<store> and C<retrieve> operations however, because |
544 | the addresses in the retrieved objects, which are part of the stringified |
545 | references, will probably differ from the original addresses. The |
546 | topology of your structure is preserved, but not hidden semantics |
547 | like those. |
548 | |
549 | On platforms where it matters, be sure to call C<binmode()> on the |
550 | descriptors that you pass to Storable functions. |
551 | |
552 | Storing data canonically that contains large hashes can be |
553 | significantly slower than storing the same data normally, as |
554 | temprorary arrays to hold the keys for each hash have to be allocated, |
555 | populated, sorted and freed. Some tests have shown a halving of the |
556 | speed of storing -- the exact penalty will depend on the complexity of |
557 | your data. There is no slowdown on retrieval. |
558 | |
559 | =head1 BUGS |
560 | |
561 | You can't store GLOB, CODE, FORMLINE, etc... If you can define |
562 | semantics for those operations, feel free to enhance Storable so that |
563 | it can deal with them. |
564 | |
565 | The store functions will C<croak> if they run into such references |
566 | unless you set C<$Storable::forgive_me> to some C<TRUE> value. In that |
567 | case, the fatal message is turned in a warning and some |
568 | meaningless string is stored instead. |
569 | |
570 | Setting C<$Storable::canonical> may not yield frozen strings that |
571 | compare equal due to possible stringification of numbers. When the |
572 | string version of a scalar exists, it is the form stored, therefore |
573 | if you happen to use your numbers as strings between two freezing |
574 | operations on the same data structures, you will get different |
575 | results. |
576 | |
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577 | =head1 CREDITS |
578 | |
579 | Thank you to (in chronological order): |
580 | |
581 | Jarkko Hietaniemi <jhi@iki.fi> |
582 | Ulrich Pfeifer <pfeifer@charly.informatik.uni-dortmund.de> |
583 | Benjamin A. Holzman <bah@ecnvantage.com> |
584 | Andrew Ford <A.Ford@ford-mason.co.uk> |
585 | Gisle Aas <gisle@aas.no> |
586 | Jeff Gresham <gresham_jeffrey@jpmorgan.com> |
587 | Murray Nesbitt <murray@activestate.com> |
588 | Marc Lehmann <pcg@opengroup.org> |
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589 | Justin Banks <justinb@wamnet.com> |
590 | Jarkko Hietaniemi <jhi@iki.fi> (AGAIN, as perl 5.7.0 Pumpkin!) |
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591 | |
592 | for their bug reports, suggestions and contributions. |
593 | |
594 | Benjamin Holzman contributed the tied variable support, Andrew Ford |
595 | contributed the canonical order for hashes, and Gisle Aas fixed |
596 | a few misunderstandings of mine regarding the Perl internals, |
597 | and optimized the emission of "tags" in the output streams by |
598 | simply counting the objects instead of tagging them (leading to |
599 | a binary incompatibility for the Storable image starting at version |
600 | 0.6--older images are of course still properly understood). |
601 | Murray Nesbitt made Storable thread-safe. Marc Lehmann added overloading |
602 | and reference to tied items support. |
603 | |
604 | =head1 TRANSLATIONS |
605 | |
606 | There is a Japanese translation of this man page available at |
607 | http://member.nifty.ne.jp/hippo2000/perltips/storable.htm , |
608 | courtesy of Kawai, Takanori <kawai@nippon-rad.co.jp>. |
609 | |
610 | =head1 AUTHOR |
611 | |
612 | Raphael Manfredi F<E<lt>Raphael_Manfredi@pobox.comE<gt>> |
613 | |
614 | =head1 SEE ALSO |
615 | |
616 | Clone(3). |
617 | |
618 | =cut |
619 | |