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[perl5.git] / ext / Data / Dumper / Dumper.pm
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1#
2# Data/Dumper.pm
3#
4# convert perl data structures into perl syntax suitable for both printing
5# and eval
6#
7# Documentation at the __END__
8#
9
10package Data::Dumper;
11
c8984b0b 12$VERSION = $VERSION = '2.101';
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13
14#$| = 1;
15
982af928 16require 5.004_02;
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17require Exporter;
18require DynaLoader;
19require overload;
20
21use Carp;
22
23@ISA = qw(Exporter DynaLoader);
24@EXPORT = qw(Dumper);
25@EXPORT_OK = qw(DumperX);
26
27bootstrap Data::Dumper;
28
29# module vars and their defaults
30$Indent = 2 unless defined $Indent;
31$Purity = 0 unless defined $Purity;
32$Pad = "" unless defined $Pad;
33$Varname = "VAR" unless defined $Varname;
34$Useqq = 0 unless defined $Useqq;
35$Terse = 0 unless defined $Terse;
36$Freezer = "" unless defined $Freezer;
37$Toaster = "" unless defined $Toaster;
38$Deepcopy = 0 unless defined $Deepcopy;
39$Quotekeys = 1 unless defined $Quotekeys;
40$Bless = "bless" unless defined $Bless;
41#$Expdepth = 0 unless defined $Expdepth;
a2126434 42$Maxdepth = 0 unless defined $Maxdepth;
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43
44#
45# expects an arrayref of values to be dumped.
46# can optionally pass an arrayref of names for the values.
47# names must have leading $ sign stripped. begin the name with *
48# to cause output of arrays and hashes rather than refs.
49#
50sub new {
51 my($c, $v, $n) = @_;
52
53 croak "Usage: PACKAGE->new(ARRAYREF, [ARRAYREF])"
54 unless (defined($v) && (ref($v) eq 'ARRAY'));
55 $n = [] unless (defined($n) && (ref($v) eq 'ARRAY'));
56
57 my($s) = {
58 level => 0, # current recursive depth
59 indent => $Indent, # various styles of indenting
60 pad => $Pad, # all lines prefixed by this string
61 xpad => "", # padding-per-level
62 apad => "", # added padding for hash keys n such
63 sep => "", # list separator
64 seen => {}, # local (nested) refs (id => [name, val])
65 todump => $v, # values to dump []
66 names => $n, # optional names for values []
67 varname => $Varname, # prefix to use for tagging nameless ones
68 purity => $Purity, # degree to which output is evalable
69 useqq => $Useqq, # use "" for strings (backslashitis ensues)
70 terse => $Terse, # avoid name output (where feasible)
71 freezer => $Freezer, # name of Freezer method for objects
72 toaster => $Toaster, # name of method to revive objects
73 deepcopy => $Deepcopy, # dont cross-ref, except to stop recursion
74 quotekeys => $Quotekeys, # quote hash keys
75 'bless' => $Bless, # keyword to use for "bless"
76# expdepth => $Expdepth, # cutoff depth for explicit dumping
a2126434 77 maxdepth => $Maxdepth, # depth beyond which we give up
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78 };
79
80 if ($Indent > 0) {
81 $s->{xpad} = " ";
82 $s->{sep} = "\n";
83 }
84 return bless($s, $c);
85}
86
87#
88# add-to or query the table of already seen references
89#
90sub Seen {
91 my($s, $g) = @_;
92 if (defined($g) && (ref($g) eq 'HASH')) {
93 my($k, $v, $id);
94 while (($k, $v) = each %$g) {
95 if (defined $v and ref $v) {
96 ($id) = (overload::StrVal($v) =~ /\((.*)\)$/);
97 if ($k =~ /^[*](.*)$/) {
98 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
99 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
100 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
101 ( "\$" . $1 ) ;
102 }
103 elsif ($k !~ /^\$/) {
104 $k = "\$" . $k;
105 }
106 $s->{seen}{$id} = [$k, $v];
107 }
108 else {
109 carp "Only refs supported, ignoring non-ref item \$$k";
110 }
111 }
112 return $s;
113 }
114 else {
115 return map { @$_ } values %{$s->{seen}};
116 }
117}
118
119#
120# set or query the values to be dumped
121#
122sub Values {
123 my($s, $v) = @_;
124 if (defined($v) && (ref($v) eq 'ARRAY')) {
125 $s->{todump} = [@$v]; # make a copy
126 return $s;
127 }
128 else {
129 return @{$s->{todump}};
130 }
131}
132
133#
134# set or query the names of the values to be dumped
135#
136sub Names {
137 my($s, $n) = @_;
138 if (defined($n) && (ref($n) eq 'ARRAY')) {
139 $s->{names} = [@$n]; # make a copy
140 return $s;
141 }
142 else {
143 return @{$s->{names}};
144 }
145}
146
147sub DESTROY {}
148
149#
150# dump the refs in the current dumper object.
151# expects same args as new() if called via package name.
152#
153sub Dump {
154 my($s) = shift;
155 my(@out, $val, $name);
156 my($i) = 0;
157 local(@post);
158
159 $s = $s->new(@_) unless ref $s;
160
161 for $val (@{$s->{todump}}) {
162 my $out = "";
163 @post = ();
164 $name = $s->{names}[$i++];
165 if (defined $name) {
166 if ($name =~ /^[*](.*)$/) {
167 if (defined $val) {
168 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
169 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
170 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
171 ( "\$" . $1 ) ;
172 }
173 else {
174 $name = "\$" . $1;
175 }
176 }
177 elsif ($name !~ /^\$/) {
178 $name = "\$" . $name;
179 }
180 }
181 else {
182 $name = "\$" . $s->{varname} . $i;
183 }
184
185 my $valstr;
186 {
187 local($s->{apad}) = $s->{apad};
188 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
189 $valstr = $s->_dump($val, $name);
190 }
191
192 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
193 $out .= $s->{pad} . $valstr . $s->{sep};
194 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
195 . ';' . $s->{sep} if @post;
196
197 push @out, $out;
198 }
199 return wantarray ? @out : join('', @out);
200}
201
202#
203# twist, toil and turn;
204# and recurse, of course.
205#
206sub _dump {
207 my($s, $val, $name) = @_;
208 my($sname);
209 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
210
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211 $type = ref $val;
212 $out = "";
213
214 if ($type) {
215
216 # prep it, if it looks like an object
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217 if (my $freezer = $s->{freezer}) {
218 $val->$freezer() if UNIVERSAL::can($val, $freezer);
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219 }
220
221 ($realpack, $realtype, $id) =
222 (overload::StrVal($val) =~ /^(?:(.*)\=)?([^=]*)\(([^\(]*)\)$/);
a2126434 223
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224 # if it has a name, we need to either look it up, or keep a tab
225 # on it so we know when we hit it later
226 if (defined($name) and length($name)) {
227 # keep a tab on it so that we dont fall into recursive pit
228 if (exists $s->{seen}{$id}) {
229# if ($s->{expdepth} < $s->{level}) {
230 if ($s->{purity} and $s->{level} > 0) {
231 $out = ($realtype eq 'HASH') ? '{}' :
232 ($realtype eq 'ARRAY') ? '[]' :
233 "''" ;
234 push @post, $name . " = " . $s->{seen}{$id}[0];
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235 }
236 else {
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237 $out = $s->{seen}{$id}[0];
238 if ($name =~ /^([\@\%])/) {
239 my $start = $1;
240 if ($out =~ /^\\$start/) {
241 $out = substr($out, 1);
242 }
243 else {
244 $out = $start . '{' . $out . '}';
245 }
246 }
247 }
248 return $out;
249# }
250 }
251 else {
252 # store our name
253 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
254 ($realtype eq 'CODE' and
255 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
256 $name ),
257 $val ];
823edd99 258 }
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259 }
260
a2126434 261 if ($realpack and $realpack eq 'Regexp') {
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262 $out = "$val";
263 $out =~ s,/,\\/,g;
264 return "qr/$out/";
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265 }
266
267 # If purity is not set and maxdepth is set, then check depth:
268 # if we have reached maximum depth, return the string
269 # representation of the thing we are currently examining
270 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
271 if (!$s->{purity}
272 and $s->{maxdepth} > 0
273 and $s->{level} >= $s->{maxdepth})
274 {
275 return qq['$val'];
276 }
277
278 # we have a blessed ref
279 if ($realpack) {
280 $out = $s->{'bless'} . '( ';
281 $blesspad = $s->{apad};
282 $s->{apad} .= ' ' if ($s->{indent} >= 2);
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283 }
284
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285 $s->{level}++;
286 $ipad = $s->{xpad} x $s->{level};
287
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288
289 if ($realtype eq 'SCALAR') {
290 if ($realpack) {
7820172a 291 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
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292 }
293 else {
7820172a 294 $out .= '\\' . $s->_dump($$val, "\${$name}");
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295 }
296 }
297 elsif ($realtype eq 'GLOB') {
7820172a 298 $out .= '\\' . $s->_dump($$val, "*{$name}");
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299 }
300 elsif ($realtype eq 'ARRAY') {
301 my($v, $pad, $mname);
302 my($i) = 0;
303 $out .= ($name =~ /^\@/) ? '(' : '[';
304 $pad = $s->{sep} . $s->{pad} . $s->{apad};
305 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
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306 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
307 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
308 ($mname = $name . '->');
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309 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
310 for $v (@$val) {
311 $sname = $mname . '[' . $i . ']';
312 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
313 $out .= $pad . $ipad . $s->_dump($v, $sname);
314 $out .= "," if $i++ < $#$val;
315 }
316 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
317 $out .= ($name =~ /^\@/) ? ')' : ']';
318 }
319 elsif ($realtype eq 'HASH') {
320 my($k, $v, $pad, $lpad, $mname);
321 $out .= ($name =~ /^\%/) ? '(' : '{';
322 $pad = $s->{sep} . $s->{pad} . $s->{apad};
323 $lpad = $s->{apad};
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324 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
325 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
326 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
327 ($mname = $name . '->');
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328 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
329 while (($k, $v) = each %$val) {
330 my $nk = $s->_dump($k, "");
331 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
332 $sname = $mname . '{' . $nk . '}';
333 $out .= $pad . $ipad . $nk . " => ";
334
335 # temporarily alter apad
336 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
337 $out .= $s->_dump($val->{$k}, $sname) . ",";
338 $s->{apad} = $lpad if $s->{indent} >= 2;
339 }
340 if (substr($out, -1) eq ',') {
341 chop $out;
342 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
343 }
344 $out .= ($name =~ /^\%/) ? ')' : '}';
345 }
346 elsif ($realtype eq 'CODE') {
c8984b0b 347 $out .= 'sub { "DUMMY" }';
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348 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
349 }
350 else {
351 croak "Can\'t handle $realtype type.";
352 }
353
354 if ($realpack) { # we have a blessed ref
355 $out .= ', \'' . $realpack . '\'' . ' )';
356 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
357 $s->{apad} = $blesspad;
358 }
359 $s->{level}--;
360
361 }
362 else { # simple scalar
363
364 my $ref = \$_[1];
365 # first, catalog the scalar
366 if ($name ne '') {
367 ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
368 if (exists $s->{seen}{$id}) {
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369 if ($s->{seen}{$id}[2]) {
370 $out = $s->{seen}{$id}[0];
371 #warn "[<$out]\n";
372 return "\${$out}";
373 }
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374 }
375 else {
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376 #warn "[>\\$name]\n";
377 $s->{seen}{$id} = ["\\$name", $ref];
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378 }
379 }
380 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
381 my $name = substr($val, 1);
382 if ($name =~ /^[A-Za-z_][\w:]*$/) {
383 $name =~ s/^main::/::/;
384 $sname = $name;
385 }
386 else {
387 $sname = $s->_dump($name, "");
388 $sname = '{' . $sname . '}';
389 }
390 if ($s->{purity}) {
391 my $k;
392 local ($s->{level}) = 0;
393 for $k (qw(SCALAR ARRAY HASH)) {
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394 my $gval = *$val{$k};
395 next unless defined $gval;
396 next if $k eq "SCALAR" && ! defined $$gval; # always there
397
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398 # _dump can push into @post, so we hold our place using $postlen
399 my $postlen = scalar @post;
400 $post[$postlen] = "\*$sname = ";
401 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
7820172a 402 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
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403 }
404 }
405 $out .= '*' . $sname;
406 }
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407 elsif (!defined($val)) {
408 $out .= "undef";
409 }
45b49486 410 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})$/) { # safe decimal number
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411 $out .= $val;
412 }
413 else { # string
414 if ($s->{useqq}) {
7820172a 415 $out .= qquote($val, $s->{useqq});
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416 }
417 else {
418 $val =~ s/([\\\'])/\\$1/g;
419 $out .= '\'' . $val . '\'';
420 }
421 }
422 }
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423 if ($id) {
424 # if we made it this far, $id was added to seen list at current
425 # level, so remove it to get deep copies
426 if ($s->{deepcopy}) {
427 delete($s->{seen}{$id});
428 }
429 elsif ($name) {
430 $s->{seen}{$id}[2] = 1;
431 }
432 }
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433 return $out;
434}
435
436#
437# non-OO style of earlier version
438#
439sub Dumper {
440 return Data::Dumper->Dump([@_]);
441}
442
443#
444# same, only calls the XS version
445#
446sub DumperX {
447 return Data::Dumper->Dumpxs([@_], []);
448}
449
450sub Dumpf { return Data::Dumper->Dump(@_) }
451
452sub Dumpp { print Data::Dumper->Dump(@_) }
453
454#
455# reset the "seen" cache
456#
457sub Reset {
458 my($s) = shift;
459 $s->{seen} = {};
460 return $s;
461}
462
463sub Indent {
464 my($s, $v) = @_;
465 if (defined($v)) {
466 if ($v == 0) {
467 $s->{xpad} = "";
468 $s->{sep} = "";
469 }
470 else {
471 $s->{xpad} = " ";
472 $s->{sep} = "\n";
473 }
474 $s->{indent} = $v;
475 return $s;
476 }
477 else {
478 return $s->{indent};
479 }
480}
481
482sub Pad {
483 my($s, $v) = @_;
484 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
485}
486
487sub Varname {
488 my($s, $v) = @_;
489 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
490}
491
492sub Purity {
493 my($s, $v) = @_;
494 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
495}
496
497sub Useqq {
498 my($s, $v) = @_;
499 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
500}
501
502sub Terse {
503 my($s, $v) = @_;
504 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
505}
506
507sub Freezer {
508 my($s, $v) = @_;
509 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
510}
511
512sub Toaster {
513 my($s, $v) = @_;
514 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
515}
516
517sub Deepcopy {
518 my($s, $v) = @_;
519 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
520}
521
522sub Quotekeys {
523 my($s, $v) = @_;
524 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
525}
526
527sub Bless {
528 my($s, $v) = @_;
529 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
530}
531
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532sub Maxdepth {
533 my($s, $v) = @_;
534 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
535}
536
537
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538# used by qquote below
539my %esc = (
540 "\a" => "\\a",
541 "\b" => "\\b",
542 "\t" => "\\t",
543 "\n" => "\\n",
544 "\f" => "\\f",
545 "\r" => "\\r",
546 "\e" => "\\e",
547);
548
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549# put a string value in double quotes
550sub qquote {
551 local($_) = shift;
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552 s/([\\\"\@\$])/\\$1/g;
553 return qq("$_") unless /[^\040-\176]/; # fast exit
554
555 my $high = shift || "";
556 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
557
558 # no need for 3 digits in escape for these
559 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
560
561 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
562 if ($high eq "iso8859") {
563 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
564 } elsif ($high eq "utf8") {
565# use utf8;
566# $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
567 } elsif ($high eq "8bit") {
568 # leave it as it is
569 } else {
570 s/([\0-\037\177-\377])/'\\'.sprintf('%03o',ord($1))/eg;
571 }
572 return qq("$_");
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573}
574
5751;
576__END__
577
578=head1 NAME
579
580Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
581
582
583=head1 SYNOPSIS
584
585 use Data::Dumper;
586
587 # simple procedural interface
588 print Dumper($foo, $bar);
589
590 # extended usage with names
591 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
592
593 # configuration variables
594 {
595 local $Data::Dump::Purity = 1;
596 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
597 }
598
599 # OO usage
600 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
601 ...
602 print $d->Dump;
603 ...
604 $d->Purity(1)->Terse(1)->Deepcopy(1);
605 eval $d->Dump;
606
607
608=head1 DESCRIPTION
609
610Given a list of scalars or reference variables, writes out their contents in
611perl syntax. The references can also be objects. The contents of each
612variable is output in a single Perl statement. Handles self-referential
613structures correctly.
614
615The return value can be C<eval>ed to get back an identical copy of the
616original reference structure.
617
618Any references that are the same as one of those passed in will be named
619C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
620to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
621notation. You can specify names for individual values to be dumped if you
622use the C<Dump()> method, or you can change the default C<$VAR> prefix to
623something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
624below.
625
626The default output of self-referential structures can be C<eval>ed, but the
627nested references to C<$VAR>I<n> will be undefined, since a recursive
628structure cannot be constructed using one Perl statement. You should set the
629C<Purity> flag to 1 to get additional statements that will correctly fill in
630these references.
631
632In the extended usage form, the references to be dumped can be given
633user-specified names. If a name begins with a C<*>, the output will
634describe the dereferenced type of the supplied reference for hashes and
635arrays, and coderefs. Output of names will be avoided where possible if
636the C<Terse> flag is set.
637
638In many cases, methods that are used to set the internal state of the
639object will return the object itself, so method calls can be conveniently
640chained together.
641
642Several styles of output are possible, all controlled by setting
643the C<Indent> flag. See L<Configuration Variables or Methods> below
644for details.
645
646
647=head2 Methods
648
649=over 4
650
651=item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
652
653Returns a newly created C<Data::Dumper> object. The first argument is an
654anonymous array of values to be dumped. The optional second argument is an
655anonymous array of names for the values. The names need not have a leading
656C<$> sign, and must be comprised of alphanumeric characters. You can begin
657a name with a C<*> to specify that the dereferenced type must be dumped
658instead of the reference itself, for ARRAY and HASH references.
659
660The prefix specified by C<$Data::Dumper::Varname> will be used with a
661numeric suffix if the name for a value is undefined.
662
663Data::Dumper will catalog all references encountered while dumping the
664values. Cross-references (in the form of names of substructures in perl
665syntax) will be inserted at all possible points, preserving any structural
666interdependencies in the original set of values. Structure traversal is
667depth-first, and proceeds in order from the first supplied value to
668the last.
669
670=item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
671
672Returns the stringified form of the values stored in the object (preserving
673the order in which they were supplied to C<new>), subject to the
674configuration options below. In an array context, it returns a list
675of strings corresponding to the supplied values.
676
677The second form, for convenience, simply calls the C<new> method on its
678arguments before dumping the object immediately.
679
680=item I<$OBJ>->Dumpxs I<or> I<PACKAGE>->Dumpxs(I<ARRAYREF [>, I<ARRAYREF]>)
681
682This method is available if you were able to compile and install the XSUB
683extension to C<Data::Dumper>. It is exactly identical to the C<Dump> method
684above, only about 4 to 5 times faster, since it is written entirely in C.
685
686=item I<$OBJ>->Seen(I<[HASHREF]>)
687
688Queries or adds to the internal table of already encountered references.
689You must use C<Reset> to explicitly clear the table if needed. Such
690references are not dumped; instead, their names are inserted wherever they
691are encountered subsequently. This is useful especially for properly
692dumping subroutine references.
693
694Expects a anonymous hash of name => value pairs. Same rules apply for names
695as in C<new>. If no argument is supplied, will return the "seen" list of
696name => value pairs, in an array context. Otherwise, returns the object
697itself.
698
699=item I<$OBJ>->Values(I<[ARRAYREF]>)
700
701Queries or replaces the internal array of values that will be dumped.
702When called without arguments, returns the values. Otherwise, returns the
703object itself.
704
705=item I<$OBJ>->Names(I<[ARRAYREF]>)
706
707Queries or replaces the internal array of user supplied names for the values
708that will be dumped. When called without arguments, returns the names.
709Otherwise, returns the object itself.
710
711=item I<$OBJ>->Reset
712
713Clears the internal table of "seen" references and returns the object
714itself.
715
716=back
717
718=head2 Functions
719
720=over 4
721
722=item Dumper(I<LIST>)
723
724Returns the stringified form of the values in the list, subject to the
725configuration options below. The values will be named C<$VAR>I<n> in the
726output, where I<n> is a numeric suffix. Will return a list of strings
727in an array context.
728
729=item DumperX(I<LIST>)
730
731Identical to the C<Dumper()> function above, but this calls the XSUB
732implementation. Only available if you were able to compile and install
733the XSUB extensions in C<Data::Dumper>.
734
735=back
736
737=head2 Configuration Variables or Methods
738
739Several configuration variables can be used to control the kind of output
740generated when using the procedural interface. These variables are usually
741C<local>ized in a block so that other parts of the code are not affected by
742the change.
743
744These variables determine the default state of the object created by calling
745the C<new> method, but cannot be used to alter the state of the object
746thereafter. The equivalent method names should be used instead to query
747or set the internal state of the object.
748
749The method forms return the object itself when called with arguments,
750so that they can be chained together nicely.
751
752=over 4
753
754=item $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
755
756Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
757spews output without any newlines, indentation, or spaces between list
758items. It is the most compact format possible that can still be called
759valid perl. Style 1 outputs a readable form with newlines but no fancy
760indentation (each level in the structure is simply indented by a fixed
761amount of whitespace). Style 2 (the default) outputs a very readable form
762which takes into account the length of hash keys (so the hash value lines
763up). Style 3 is like style 2, but also annotates the elements of arrays
764with their index (but the comment is on its own line, so array output
765consumes twice the number of lines). Style 2 is the default.
766
767=item $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
768
769Controls the degree to which the output can be C<eval>ed to recreate the
770supplied reference structures. Setting it to 1 will output additional perl
771statements that will correctly recreate nested references. The default is
7720.
773
774=item $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
775
776Specifies the string that will be prefixed to every line of the output.
777Empty string by default.
778
779=item $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
780
781Contains the prefix to use for tagging variable names in the output. The
782default is "VAR".
783
784=item $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
785
786When set, enables the use of double quotes for representing string values.
787Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
788characters will be backslashed, and unprintable characters will be output as
789quoted octal integers. Since setting this variable imposes a performance
790penalty, the default is 0. The C<Dumpxs()> method does not honor this
791flag yet.
792
793=item $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
794
795When set, Data::Dumper will emit single, non-self-referential values as
796atoms/terms rather than statements. This means that the C<$VAR>I<n> names
797will be avoided where possible, but be advised that such output may not
798always be parseable by C<eval>.
799
800=item $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
801
802Can be set to a method name, or to an empty string to disable the feature.
803Data::Dumper will invoke that method via the object before attempting to
804stringify it. This method can alter the contents of the object (if, for
805instance, it contains data allocated from C), and even rebless it in a
806different package. The client is responsible for making sure the specified
807method can be called via the object, and that the object ends up containing
808only perl data types after the method has been called. Defaults to an empty
809string.
810
811=item $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
812
813Can be set to a method name, or to an empty string to disable the feature.
814Data::Dumper will emit a method call for any objects that are to be dumped
815using the syntax C<bless(DATA, CLASS)->METHOD()>. Note that this means that
816the method specified will have to perform any modifications required on the
817object (like creating new state within it, and/or reblessing it in a
818different package) and then return it. The client is responsible for making
819sure the method can be called via the object, and that it returns a valid
820object. Defaults to an empty string.
821
822=item $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
823
824Can be set to a boolean value to enable deep copies of structures.
825Cross-referencing will then only be done when absolutely essential
826(i.e., to break reference cycles). Default is 0.
827
828=item $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
829
830Can be set to a boolean value to control whether hash keys are quoted.
831A false value will avoid quoting hash keys when it looks like a simple
832string. Default is 1, which will always enclose hash keys in quotes.
833
834=item $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
835
836Can be set to a string that specifies an alternative to the C<bless>
837builtin operator used to create objects. A function with the specified
838name should exist, and should accept the same arguments as the builtin.
839Default is C<bless>.
840
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841=item $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
842
843Can be set to a positive integer that specifies the depth beyond which
844which we don't venture into a structure. Has no effect when
845C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
846want to see more than enough). Default is 0, which means there is
847no maximum depth.
848
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849=back
850
851=head2 Exports
852
853=over 4
854
855=item Dumper
856
857=back
858
859=head1 EXAMPLES
860
861Run these code snippets to get a quick feel for the behavior of this
862module. When you are through with these examples, you may want to
863add or change the various configuration variables described above,
864to see their behavior. (See the testsuite in the Data::Dumper
865distribution for more examples.)
866
867
868 use Data::Dumper;
869
870 package Foo;
871 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
872
873 package Fuz; # a weird REF-REF-SCALAR object
874 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
875
876 package main;
877 $foo = Foo->new;
878 $fuz = Fuz->new;
879 $boo = [ 1, [], "abcd", \*foo,
880 {1 => 'a', 023 => 'b', 0x45 => 'c'},
881 \\"p\q\'r", $foo, $fuz];
882
883 ########
884 # simple usage
885 ########
886
887 $bar = eval(Dumper($boo));
888 print($@) if $@;
889 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
890
891 $Data::Dumper::Terse = 1; # don't output names where feasible
892 $Data::Dumper::Indent = 0; # turn off all pretty print
893 print Dumper($boo), "\n";
894
895 $Data::Dumper::Indent = 1; # mild pretty print
896 print Dumper($boo);
897
898 $Data::Dumper::Indent = 3; # pretty print with array indices
899 print Dumper($boo);
900
901 $Data::Dumper::Useqq = 1; # print strings in double quotes
902 print Dumper($boo);
903
904
905 ########
906 # recursive structures
907 ########
908
909 @c = ('c');
910 $c = \@c;
911 $b = {};
912 $a = [1, $b, $c];
913 $b->{a} = $a;
914 $b->{b} = $a->[1];
915 $b->{c} = $a->[2];
916 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
917
918
919 $Data::Dumper::Purity = 1; # fill in the holes for eval
920 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
921 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
922
923
924 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
925 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
926
927
928 $Data::Dumper::Purity = 0; # avoid cross-refs
929 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
930
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931 ########
932 # deep structures
933 ########
934
935 $a = "pearl";
936 $b = [ $a ];
937 $c = { 'b' => $b };
938 $d = [ $c ];
939 $e = { 'd' => $d };
940 $f = { 'e' => $e };
941 print Data::Dumper->Dump([$f], [qw(f)]);
942
943 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
944 print Data::Dumper->Dump([$f], [qw(f)]);
945
823edd99
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946
947 ########
948 # object-oriented usage
949 ########
950
951 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
952 $d->Seen({'*c' => $c}); # stash a ref without printing it
953 $d->Indent(3);
954 print $d->Dump;
955 $d->Reset->Purity(0); # empty the seen cache
956 print join "----\n", $d->Dump;
957
958
959 ########
960 # persistence
961 ########
962
963 package Foo;
964 sub new { bless { state => 'awake' }, shift }
965 sub Freeze {
966 my $s = shift;
967 print STDERR "preparing to sleep\n";
968 $s->{state} = 'asleep';
969 return bless $s, 'Foo::ZZZ';
970 }
971
972 package Foo::ZZZ;
973 sub Thaw {
974 my $s = shift;
975 print STDERR "waking up\n";
976 $s->{state} = 'awake';
977 return bless $s, 'Foo';
978 }
979
980 package Foo;
981 use Data::Dumper;
982 $a = Foo->new;
983 $b = Data::Dumper->new([$a], ['c']);
984 $b->Freezer('Freeze');
985 $b->Toaster('Thaw');
986 $c = $b->Dump;
987 print $c;
988 $d = eval $c;
989 print Data::Dumper->Dump([$d], ['d']);
990
991
992 ########
993 # symbol substitution (useful for recreating CODE refs)
994 ########
995
996 sub foo { print "foo speaking\n" }
997 *other = \&foo;
998 $bar = [ \&other ];
999 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1000 $d->Seen({ '*foo' => \&foo });
1001 print $d->Dump;
1002
1003
1004=head1 BUGS
1005
1006Due to limitations of Perl subroutine call semantics, you cannot pass an
1007array or hash. Prepend it with a C<\> to pass its reference instead. This
1008will be remedied in time, with the arrival of prototypes in later versions
1009of Perl. For now, you need to use the extended usage form, and prepend the
1010name with a C<*> to output it as a hash or array.
1011
1012C<Data::Dumper> cheats with CODE references. If a code reference is
1013encountered in the structure being processed, an anonymous subroutine that
1014contains the string '"DUMMY"' will be inserted in its place, and a warning
1015will be printed if C<Purity> is set. You can C<eval> the result, but bear
1016in mind that the anonymous sub that gets created is just a placeholder.
1017Someday, perl will have a switch to cache-on-demand the string
1018representation of a compiled piece of code, I hope. If you have prior
1019knowledge of all the code refs that your data structures are likely
1020to have, you can use the C<Seen> method to pre-seed the internal reference
1021table and make the dumped output point to them, instead. See L<EXAMPLES>
1022above.
1023
1024The C<Useqq> flag is not honored by C<Dumpxs()> (it always outputs
1025strings in single quotes).
1026
1027SCALAR objects have the weirdest looking C<bless> workaround.
1028
1029
1030=head1 AUTHOR
1031
1032Gurusamy Sarathy gsar@umich.edu
1033
1034Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1035This program is free software; you can redistribute it and/or
1036modify it under the same terms as Perl itself.
1037
1038
1039=head1 VERSION
1040
a2126434 1041Version 2.11 (unreleased)
823edd99
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1042
1043=head1 SEE ALSO
1044
1045perl(1)
1046
1047=cut