4 # convert perl data structures into perl syntax suitable for both printing
7 # Documentation at the __END__
13 $VERSION = '2.167_02'; # Don't forget to set version and release
14 } # date in POD below!
21 use constant IS_PRE_520_PERL => $] < 5.020;
28 @EXPORT_OK = qw(DumperX);
30 # if run under miniperl, or otherwise lacking dynamic loading,
31 # XSLoader should be attempted to load, or the pure perl flag
32 # toggled on load failure.
35 XSLoader::load( 'Data::Dumper' );
41 my $IS_ASCII = ord 'A' == 65;
43 # module vars and their defaults
44 $Indent = 2 unless defined $Indent;
45 $Trailingcomma = 0 unless defined $Trailingcomma;
46 $Purity = 0 unless defined $Purity;
47 $Pad = "" unless defined $Pad;
48 $Varname = "VAR" unless defined $Varname;
49 $Useqq = 0 unless defined $Useqq;
50 $Terse = 0 unless defined $Terse;
51 $Freezer = "" unless defined $Freezer;
52 $Toaster = "" unless defined $Toaster;
53 $Deepcopy = 0 unless defined $Deepcopy;
54 $Quotekeys = 1 unless defined $Quotekeys;
55 $Bless = "bless" unless defined $Bless;
56 #$Expdepth = 0 unless defined $Expdepth;
57 $Maxdepth = 0 unless defined $Maxdepth;
58 $Pair = ' => ' unless defined $Pair;
59 $Useperl = 0 unless defined $Useperl;
60 $Sortkeys = 0 unless defined $Sortkeys;
61 $Deparse = 0 unless defined $Deparse;
62 $Sparseseen = 0 unless defined $Sparseseen;
63 $Maxrecurse = 1000 unless defined $Maxrecurse;
66 # expects an arrayref of values to be dumped.
67 # can optionally pass an arrayref of names for the values.
68 # names must have leading $ sign stripped. begin the name with *
69 # to cause output of arrays and hashes rather than refs.
74 Carp::croak("Usage: PACKAGE->new(ARRAYREF, [ARRAYREF])")
75 unless (defined($v) && (ref($v) eq 'ARRAY'));
76 $n = [] unless (defined($n) && (ref($n) eq 'ARRAY'));
79 level => 0, # current recursive depth
80 indent => $Indent, # various styles of indenting
81 trailingcomma => $Trailingcomma, # whether to add comma after last elem
82 pad => $Pad, # all lines prefixed by this string
83 xpad => "", # padding-per-level
84 apad => "", # added padding for hash keys n such
85 sep => "", # list separator
86 pair => $Pair, # hash key/value separator: defaults to ' => '
87 seen => {}, # local (nested) refs (id => [name, val])
88 todump => $v, # values to dump []
89 names => $n, # optional names for values []
90 varname => $Varname, # prefix to use for tagging nameless ones
91 purity => $Purity, # degree to which output is evalable
92 useqq => $Useqq, # use "" for strings (backslashitis ensues)
93 terse => $Terse, # avoid name output (where feasible)
94 freezer => $Freezer, # name of Freezer method for objects
95 toaster => $Toaster, # name of method to revive objects
96 deepcopy => $Deepcopy, # do not cross-ref, except to stop recursion
97 quotekeys => $Quotekeys, # quote hash keys
98 'bless' => $Bless, # keyword to use for "bless"
99 # expdepth => $Expdepth, # cutoff depth for explicit dumping
100 maxdepth => $Maxdepth, # depth beyond which we give up
101 maxrecurse => $Maxrecurse, # depth beyond which we abort
102 useperl => $Useperl, # use the pure Perl implementation
103 sortkeys => $Sortkeys, # flag or filter for sorting hash keys
104 deparse => $Deparse, # use B::Deparse for coderefs
105 noseen => $Sparseseen, # do not populate the seen hash unless necessary
112 return bless($s, $c);
115 # Packed numeric addresses take less memory. Plus pack is faster than sprintf
117 # Most users of current versions of Data::Dumper will be 5.008 or later.
118 # Anyone on 5.6.1 and 5.6.2 upgrading will be rare (particularly judging by
119 # the bug reports from users on those platforms), so for the common case avoid
120 # complexity, and avoid even compiling the unneeded code.
122 sub init_refaddr_format {
126 require Scalar::Util;
127 pack "J", Scalar::Util::refaddr(shift);
132 no warnings 'redefine';
134 sub init_refaddr_format {
136 my $f = $Config::Config{uvxformat};
138 $refaddr_format = "0x%" . $f;
142 require Scalar::Util;
143 sprintf $refaddr_format, Scalar::Util::refaddr(shift);
151 # add-to or query the table of already seen references
155 if (defined($g) && (ref($g) eq 'HASH')) {
156 init_refaddr_format();
158 while (($k, $v) = each %$g) {
161 $id = format_refaddr($v);
162 if ($k =~ /^[*](.*)$/) {
163 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
164 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
165 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
168 elsif ($k !~ /^\$/) {
171 $s->{seen}{$id} = [$k, $v];
174 Carp::carp("Only refs supported, ignoring non-ref item \$$k");
178 Carp::carp("Value of ref must be defined; ignoring undefined item \$$k");
184 return map { @$_ } values %{$s->{seen}};
189 # set or query the values to be dumped
194 if (ref($v) eq 'ARRAY') {
195 $s->{todump} = [@$v]; # make a copy
199 Carp::croak("Argument to Values, if provided, must be array ref");
203 return @{$s->{todump}};
208 # set or query the names of the values to be dumped
213 if (ref($n) eq 'ARRAY') {
214 $s->{names} = [@$n]; # make a copy
218 Carp::croak("Argument to Names, if provided, must be array ref");
222 return @{$s->{names}};
229 # On old versions of perl, the xs-deparse support can fail
230 # mysteriously. Barring copious spare time, it's best to revert
231 # to the previously standard behavior of using the pure perl dumper
232 # for deparsing on old perls. --Steffen
233 if (IS_PRE_520_PERL and ($Data::Dumper::Deparse or (ref($_[0]) && $_[0]->{deparse}))) {
238 unless $Data::Dumper::Useperl || (ref($_[0]) && $_[0]->{useperl})
239 # Use pure perl version on earlier releases on EBCDIC platforms
240 || (! $IS_ASCII && $] lt 5.021_010);
245 # dump the refs in the current dumper object.
246 # expects same args as new() if called via package name.
250 my(@out, $val, $name);
253 init_refaddr_format();
255 $s = $s->new(@_) unless ref $s;
257 for $val (@{$s->{todump}}) {
259 $name = $s->{names}[$i++];
260 $name = $s->_refine_name($name, $val, $i);
264 local($s->{apad}) = $s->{apad};
265 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2 and !$s->{terse};
266 $valstr = $s->_dump($val, $name);
269 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
270 my $out = $s->_compose_out($valstr, \@post);
274 return wantarray ? @out : join('', @out);
277 # wrap string in single quotes (escaping if needed)
280 $val =~ s/([\\\'])/\\$1/g;
281 return "'" . $val . "'";
284 # Old Perls (5.14-) have trouble resetting vstring magic when it is no
286 use constant _bad_vsmg => defined &_vstring && (_vstring(~v0)||'') eq "v0";
289 # twist, toil and turn;
290 # and recurse, of course.
291 # sometimes sordidly;
292 # and curse if no recourse.
295 my($s, $val, $name) = @_;
296 my($out, $type, $id, $sname);
303 # Call the freezer method if it's specified and the object has the
304 # method. Trap errors and warn() instead of die()ing, like the XS
306 my $freezer = $s->{freezer};
307 if ($freezer and UNIVERSAL::can($val, $freezer)) {
308 eval { $val->$freezer() };
309 warn "WARNING(Freezer method call failed): $@" if $@;
312 require Scalar::Util;
313 my $realpack = Scalar::Util::blessed($val);
314 my $realtype = $realpack ? Scalar::Util::reftype($val) : ref $val;
315 $id = format_refaddr($val);
317 # Note: By this point $name is always defined and of non-zero length.
318 # Keep a tab on it so that we do not fall into recursive pit.
319 if (exists $s->{seen}{$id}) {
320 if ($s->{purity} and $s->{level} > 0) {
321 $out = ($realtype eq 'HASH') ? '{}' :
322 ($realtype eq 'ARRAY') ? '[]' :
324 push @post, $name . " = " . $s->{seen}{$id}[0];
327 $out = $s->{seen}{$id}[0];
328 if ($name =~ /^([\@\%])/) {
330 if ($out =~ /^\\$start/) {
331 $out = substr($out, 1);
334 $out = $start . '{' . $out . '}';
342 $s->{seen}{$id} = [ (
345 : ($realtype eq 'CODE' and $name =~ /^[*](.*)$/)
352 if ( $realpack and ($] >= 5.009005 ? re::is_regexp($val) : $realpack eq 'Regexp') ) {
354 $no_bless = $realpack eq 'Regexp';
357 # If purity is not set and maxdepth is set, then check depth:
358 # if we have reached maximum depth, return the string
359 # representation of the thing we are currently examining
360 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
362 and defined($s->{maxdepth})
363 and $s->{maxdepth} > 0
364 and $s->{level} >= $s->{maxdepth})
369 # avoid recursing infinitely [perl #122111]
370 if ($s->{maxrecurse} > 0
371 and $s->{level} >= $s->{maxrecurse}) {
372 die "Recursion limit of $s->{maxrecurse} exceeded";
375 # we have a blessed ref
377 if ($realpack and !$no_bless) {
378 $out = $s->{'bless'} . '( ';
379 $blesspad = $s->{apad};
380 $s->{apad} .= ' ' if ($s->{indent} >= 2);
384 my $ipad = $s->{xpad} x $s->{level};
389 if (defined(*re::regexp_pattern{CODE})) {
390 ($pat, $flags) = re::regexp_pattern($val);
395 $pat =~ s <(\\.)|/> { $1 || '\\/' }ge;
396 $out .= "qr/$pat/$flags";
398 elsif ($realtype eq 'SCALAR' || $realtype eq 'REF'
399 || $realtype eq 'VSTRING') {
401 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
404 $out .= '\\' . $s->_dump($$val, "\${$name}");
407 elsif ($realtype eq 'GLOB') {
408 $out .= '\\' . $s->_dump($$val, "*{$name}");
410 elsif ($realtype eq 'ARRAY') {
413 $out .= ($name =~ /^\@/) ? '(' : '[';
414 $pad = $s->{sep} . $s->{pad} . $s->{apad};
415 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
416 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
417 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
418 ($mname = $name . '->');
419 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
421 $sname = $mname . '[' . $i . ']';
422 $out .= $pad . $ipad . '#' . $i
423 if $s->{indent} >= 3;
424 $out .= $pad . $ipad . $s->_dump($v, $sname);
427 || ($s->{trailingcomma} && $s->{indent} >= 1);
429 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
430 $out .= ($name =~ /^\@/) ? ')' : ']';
432 elsif ($realtype eq 'HASH') {
433 my ($k, $v, $pad, $lpad, $mname, $pair);
434 $out .= ($name =~ /^\%/) ? '(' : '{';
435 $pad = $s->{sep} . $s->{pad} . $s->{apad};
438 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
439 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
440 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
441 ($mname = $name . '->');
442 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
443 my $sortkeys = defined($s->{sortkeys}) ? $s->{sortkeys} : '';
446 if (ref($s->{sortkeys}) eq 'CODE') {
447 $keys = $s->{sortkeys}($val);
448 unless (ref($keys) eq 'ARRAY') {
449 Carp::carp("Sortkeys subroutine did not return ARRAYREF");
454 $keys = [ sort keys %$val ];
458 # Ensure hash iterator is reset
462 while (($k, $v) = ! $sortkeys ? (each %$val) :
463 @$keys ? ($key = shift(@$keys), $val->{$key}) :
466 my $nk = $s->_dump($k, "");
468 # _dump doesn't quote numbers of this form
469 if ($s->{quotekeys} && $nk =~ /^(?:0|-?[1-9][0-9]{0,8})\z/) {
470 $nk = $s->{useqq} ? qq("$nk") : qq('$nk');
472 elsif (!$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/) {
476 $sname = $mname . '{' . $nk . '}';
477 $out .= $pad . $ipad . $nk . $pair;
479 # temporarily alter apad
480 $s->{apad} .= (" " x (length($nk) + 4))
481 if $s->{indent} >= 2;
482 $out .= $s->_dump($val->{$k}, $sname) . ",";
484 if $s->{indent} >= 2;
486 if (substr($out, -1) eq ',') {
487 chop $out if !$s->{trailingcomma} || !$s->{indent};
488 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
490 $out .= ($name =~ /^\%/) ? ')' : '}';
492 elsif ($realtype eq 'CODE') {
495 my $sub = 'sub ' . (B::Deparse->new)->coderef2text($val);
496 $pad = $s->{sep} . $s->{pad} . $s->{apad} . $s->{xpad} x ($s->{level} - 1);
497 $sub =~ s/\n/$pad/gs;
501 $out .= 'sub { "DUMMY" }';
502 Carp::carp("Encountered CODE ref, using dummy placeholder") if $s->{purity};
506 Carp::croak("Can't handle '$realtype' type");
509 if ($realpack and !$no_bless) { # we have a blessed ref
510 $out .= ', ' . _quote($realpack) . ' )';
511 $out .= '->' . $s->{toaster} . '()'
512 if $s->{toaster} ne '';
513 $s->{apad} = $blesspad;
517 else { # simple scalar
521 # first, catalog the scalar
523 $id = format_refaddr($ref);
524 if (exists $s->{seen}{$id}) {
525 if ($s->{seen}{$id}[2]) {
526 $out = $s->{seen}{$id}[0];
532 #warn "[>\\$name]\n";
533 $s->{seen}{$id} = ["\\$name", $ref];
537 if (ref($ref) eq 'GLOB') { # glob
538 my $name = substr($val, 1);
539 if ($name =~ /^[A-Za-z_][\w:]*$/ && $name ne 'main::') {
540 $name =~ s/^main::/::/;
545 $name eq 'main::' || $] < 5.007 && $name eq "main::\0"
550 $sname = '{' . $sname . '}';
554 local ($s->{level}) = 0;
555 for $k (qw(SCALAR ARRAY HASH)) {
556 my $gval = *$val{$k};
557 next unless defined $gval;
558 next if $k eq "SCALAR" && ! defined $$gval; # always there
560 # _dump can push into @post, so we hold our place using $postlen
561 my $postlen = scalar @post;
562 $post[$postlen] = "\*$sname = ";
563 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
564 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
567 $out .= '*' . $sname;
569 elsif (!defined($val)) {
572 elsif (defined &_vstring and $v = _vstring($val)
573 and !_bad_vsmg || eval $v eq $val) {
576 elsif (!defined &_vstring
577 and ref $ref eq 'VSTRING' || eval{Scalar::Util::isvstring($val)}) {
578 $out .= sprintf "%vd", $val;
580 # \d here would treat "1\x{660}" as a safe decimal number
581 elsif ($val =~ /^(?:0|-?[1-9][0-9]{0,8})\z/) { # safe decimal number
585 if ($s->{useqq} or $val =~ tr/\0-\377//c) {
586 # Fall back to qq if there's Unicode
587 $out .= qquote($val, $s->{useqq});
590 $out .= _quote($val);
595 # if we made it this far, $id was added to seen list at current
596 # level, so remove it to get deep copies
597 if ($s->{deepcopy}) {
598 delete($s->{seen}{$id});
601 $s->{seen}{$id}[2] = 1;
608 # non-OO style of earlier version
611 return Data::Dumper->Dump([@_]);
616 return Data::Dumper->Dumpxs([@_], []);
620 # reset the "seen" cache
649 defined($v) ? (($s->{trailingcomma} = $v), return $s) : $s->{trailingcomma};
654 defined($v) ? (($s->{pair} = $v), return $s) : $s->{pair};
659 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
664 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
669 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
674 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
679 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
684 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
689 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
694 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
699 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
704 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
709 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
714 defined($v) ? (($s->{'maxrecurse'} = $v), return $s) : $s->{'maxrecurse'};
719 defined($v) ? (($s->{'useperl'} = $v), return $s) : $s->{'useperl'};
724 defined($v) ? (($s->{'sortkeys'} = $v), return $s) : $s->{'sortkeys'};
729 defined($v) ? (($s->{'deparse'} = $v), return $s) : $s->{'deparse'};
734 defined($v) ? (($s->{'noseen'} = $v), return $s) : $s->{'noseen'};
737 # used by qquote below
748 my $low_controls = ($IS_ASCII)
750 # This includes \177, because traditionally it has been
751 # output as octal, even though it isn't really a "low"
755 # EBCDIC low controls.
758 # put a string value in double quotes
761 s/([\\\"\@\$])/\\$1/g;
763 # This efficiently changes the high ordinal characters to \x{} if the utf8
764 # flag is on. On ASCII platforms, the high ordinals are all the
765 # non-ASCII's. On EBCDIC platforms, we don't include in these the non-ASCII
766 # controls whose ordinals are less than SPACE, excluded below by the range
767 # \0-\x3f. On ASCII platforms this range just compiles as part of :ascii:.
768 # On EBCDIC platforms, there is just one outlier high ordinal control, and
769 # it gets output as \x{}.
770 my $bytes; { use bytes; $bytes = length }
771 s/([^[:ascii:]\0-\x3f])/sprintf("\\x{%x}",ord($1))/ge
774 # The above doesn't get the EBCDIC outlier high ordinal control when
775 # the string is UTF-8 but there are no UTF-8 variant characters in it.
776 # We want that to come out as \x{} anyway. We need is_utf8() to do
778 || (! $IS_ASCII && $] ge 5.008_001 && utf8::is_utf8($_));
780 return qq("$_") unless /[[:^print:]]/; # fast exit if only printables
782 # Here, there is at least one non-printable to output. First, translate the
784 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
786 # no need for 3 digits in escape for octals not followed by a digit.
787 s/($low_controls)(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
789 # But otherwise use 3 digits
790 s/($low_controls)/'\\'.sprintf('%03o',ord($1))/eg;
792 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
793 my $high = shift || "";
794 if ($high eq "iso8859") { # Doesn't escape the Latin1 printables
796 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
798 elsif ($] ge 5.007_003) {
799 my $high_control = utf8::unicode_to_native(0x9F);
800 s/$high_control/sprintf('\\%o',ord($1))/eg;
802 } elsif ($high eq "utf8") {
803 # Some discussion of what to do here is in
804 # https://rt.perl.org/Ticket/Display.html?id=113088
806 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
807 } elsif ($high eq "8bit") {
810 s/([[:^ascii:]])/'\\'.sprintf('%03o',ord($1))/eg;
811 #s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
817 # helper sub to sort hash keys in Perl < 5.8.0 where we don't have
818 # access to sortsv() from XS
819 sub _sortkeys { [ sort keys %{$_[0]} ] }
823 my ($name, $val, $i) = @_;
825 if ($name =~ /^[*](.*)$/) {
827 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
828 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
829 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
836 elsif ($name !~ /^\$/) {
837 $name = "\$" . $name;
840 else { # no names provided
841 $name = "\$" . $s->{varname} . $i;
848 my ($valstr, $postref) = @_;
850 $out .= $s->{pad} . $valstr . $s->{sep};
853 join(';' . $s->{sep} . $s->{pad}, @{$postref}) .
865 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
871 # simple procedural interface
872 print Dumper($foo, $bar);
874 # extended usage with names
875 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
877 # configuration variables
879 local $Data::Dumper::Purity = 1;
880 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
884 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
888 $d->Purity(1)->Terse(1)->Deepcopy(1);
894 Given a list of scalars or reference variables, writes out their contents in
895 perl syntax. The references can also be objects. The content of each
896 variable is output in a single Perl statement. Handles self-referential
897 structures correctly.
899 The return value can be C<eval>ed to get back an identical copy of the
900 original reference structure. (Please do consider the security implications
901 of eval'ing code from untrusted sources!)
903 Any references that are the same as one of those passed in will be named
904 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
905 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
906 notation. You can specify names for individual values to be dumped if you
907 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
908 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
911 The default output of self-referential structures can be C<eval>ed, but the
912 nested references to C<$VAR>I<n> will be undefined, since a recursive
913 structure cannot be constructed using one Perl statement. You should set the
914 C<Purity> flag to 1 to get additional statements that will correctly fill in
915 these references. Moreover, if C<eval>ed when strictures are in effect,
916 you need to ensure that any variables it accesses are previously declared.
918 In the extended usage form, the references to be dumped can be given
919 user-specified names. If a name begins with a C<*>, the output will
920 describe the dereferenced type of the supplied reference for hashes and
921 arrays, and coderefs. Output of names will be avoided where possible if
922 the C<Terse> flag is set.
924 In many cases, methods that are used to set the internal state of the
925 object will return the object itself, so method calls can be conveniently
928 Several styles of output are possible, all controlled by setting
929 the C<Indent> flag. See L<Configuration Variables or Methods> below
937 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
939 Returns a newly created C<Data::Dumper> object. The first argument is an
940 anonymous array of values to be dumped. The optional second argument is an
941 anonymous array of names for the values. The names need not have a leading
942 C<$> sign, and must be comprised of alphanumeric characters. You can begin
943 a name with a C<*> to specify that the dereferenced type must be dumped
944 instead of the reference itself, for ARRAY and HASH references.
946 The prefix specified by C<$Data::Dumper::Varname> will be used with a
947 numeric suffix if the name for a value is undefined.
949 Data::Dumper will catalog all references encountered while dumping the
950 values. Cross-references (in the form of names of substructures in perl
951 syntax) will be inserted at all possible points, preserving any structural
952 interdependencies in the original set of values. Structure traversal is
953 depth-first, and proceeds in order from the first supplied value to
956 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
958 Returns the stringified form of the values stored in the object (preserving
959 the order in which they were supplied to C<new>), subject to the
960 configuration options below. In a list context, it returns a list
961 of strings corresponding to the supplied values.
963 The second form, for convenience, simply calls the C<new> method on its
964 arguments before dumping the object immediately.
966 =item I<$OBJ>->Seen(I<[HASHREF]>)
968 Queries or adds to the internal table of already encountered references.
969 You must use C<Reset> to explicitly clear the table if needed. Such
970 references are not dumped; instead, their names are inserted wherever they
971 are encountered subsequently. This is useful especially for properly
972 dumping subroutine references.
974 Expects an anonymous hash of name => value pairs. Same rules apply for names
975 as in C<new>. If no argument is supplied, will return the "seen" list of
976 name => value pairs, in a list context. Otherwise, returns the object
979 =item I<$OBJ>->Values(I<[ARRAYREF]>)
981 Queries or replaces the internal array of values that will be dumped. When
982 called without arguments, returns the values as a list. When called with a
983 reference to an array of replacement values, returns the object itself. When
984 called with any other type of argument, dies.
986 =item I<$OBJ>->Names(I<[ARRAYREF]>)
988 Queries or replaces the internal array of user supplied names for the values
989 that will be dumped. When called without arguments, returns the names. When
990 called with an array of replacement names, returns the object itself. If the
991 number of replacement names exceeds the number of values to be named, the
992 excess names will not be used. If the number of replacement names falls short
993 of the number of values to be named, the list of replacement names will be
994 exhausted and remaining values will not be renamed. When
995 called with any other type of argument, dies.
999 Clears the internal table of "seen" references and returns the object
1008 =item Dumper(I<LIST>)
1010 Returns the stringified form of the values in the list, subject to the
1011 configuration options below. The values will be named C<$VAR>I<n> in the
1012 output, where I<n> is a numeric suffix. Will return a list of strings
1017 =head2 Configuration Variables or Methods
1019 Several configuration variables can be used to control the kind of output
1020 generated when using the procedural interface. These variables are usually
1021 C<local>ized in a block so that other parts of the code are not affected by
1024 These variables determine the default state of the object created by calling
1025 the C<new> method, but cannot be used to alter the state of the object
1026 thereafter. The equivalent method names should be used instead to query
1027 or set the internal state of the object.
1029 The method forms return the object itself when called with arguments,
1030 so that they can be chained together nicely.
1036 $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
1038 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
1039 spews output without any newlines, indentation, or spaces between list
1040 items. It is the most compact format possible that can still be called
1041 valid perl. Style 1 outputs a readable form with newlines but no fancy
1042 indentation (each level in the structure is simply indented by a fixed
1043 amount of whitespace). Style 2 (the default) outputs a very readable form
1044 which takes into account the length of hash keys (so the hash value lines
1045 up). Style 3 is like style 2, but also annotates the elements of arrays
1046 with their index (but the comment is on its own line, so array output
1047 consumes twice the number of lines). Style 2 is the default.
1051 $Data::Dumper::Trailingcomma I<or> I<$OBJ>->Trailingcomma(I<[NEWVAL]>)
1053 Controls whether a comma is added after the last element of an array or
1054 hash. Even when true, no comma is added between the last element of an array
1055 or hash and a closing bracket when they appear on the same line. The default
1060 $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
1062 Controls the degree to which the output can be C<eval>ed to recreate the
1063 supplied reference structures. Setting it to 1 will output additional perl
1064 statements that will correctly recreate nested references. The default is
1069 $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
1071 Specifies the string that will be prefixed to every line of the output.
1072 Empty string by default.
1076 $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
1078 Contains the prefix to use for tagging variable names in the output. The
1083 $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
1085 When set, enables the use of double quotes for representing string values.
1086 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
1087 characters will be backslashed, and unprintable characters will be output as
1088 quoted octal integers. The default is 0.
1092 $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
1094 When set, Data::Dumper will emit single, non-self-referential values as
1095 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
1096 will be avoided where possible, but be advised that such output may not
1097 always be parseable by C<eval>.
1101 $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
1103 Can be set to a method name, or to an empty string to disable the feature.
1104 Data::Dumper will invoke that method via the object before attempting to
1105 stringify it. This method can alter the contents of the object (if, for
1106 instance, it contains data allocated from C), and even rebless it in a
1107 different package. The client is responsible for making sure the specified
1108 method can be called via the object, and that the object ends up containing
1109 only perl data types after the method has been called. Defaults to an empty
1112 If an object does not support the method specified (determined using
1113 UNIVERSAL::can()) then the call will be skipped. If the method dies a
1114 warning will be generated.
1118 $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
1120 Can be set to a method name, or to an empty string to disable the feature.
1121 Data::Dumper will emit a method call for any objects that are to be dumped
1122 using the syntax C<bless(DATA, CLASS)-E<gt>METHOD()>. Note that this means that
1123 the method specified will have to perform any modifications required on the
1124 object (like creating new state within it, and/or reblessing it in a
1125 different package) and then return it. The client is responsible for making
1126 sure the method can be called via the object, and that it returns a valid
1127 object. Defaults to an empty string.
1131 $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
1133 Can be set to a boolean value to enable deep copies of structures.
1134 Cross-referencing will then only be done when absolutely essential
1135 (i.e., to break reference cycles). Default is 0.
1139 $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
1141 Can be set to a boolean value to control whether hash keys are quoted.
1142 A defined false value will avoid quoting hash keys when it looks like a simple
1143 string. Default is 1, which will always enclose hash keys in quotes.
1147 $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
1149 Can be set to a string that specifies an alternative to the C<bless>
1150 builtin operator used to create objects. A function with the specified
1151 name should exist, and should accept the same arguments as the builtin.
1152 Default is C<bless>.
1156 $Data::Dumper::Pair I<or> $I<OBJ>->Pair(I<[NEWVAL]>)
1158 Can be set to a string that specifies the separator between hash keys
1159 and values. To dump nested hash, array and scalar values to JavaScript,
1160 use: C<$Data::Dumper::Pair = ' : ';>. Implementing C<bless> in JavaScript
1161 is left as an exercise for the reader.
1162 A function with the specified name exists, and accepts the same arguments
1165 Default is: C< =E<gt> >.
1169 $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
1171 Can be set to a positive integer that specifies the depth beyond which
1172 we don't venture into a structure. Has no effect when
1173 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
1174 want to see more than enough). Default is 0, which means there is
1179 $Data::Dumper::Maxrecurse I<or> $I<OBJ>->Maxrecurse(I<[NEWVAL]>)
1181 Can be set to a positive integer that specifies the depth beyond which
1182 recursion into a structure will throw an exception. This is intended
1183 as a security measure to prevent perl running out of stack space when
1184 dumping an excessively deep structure. Can be set to 0 to remove the
1185 limit. Default is 1000.
1189 $Data::Dumper::Useperl I<or> $I<OBJ>->Useperl(I<[NEWVAL]>)
1191 Can be set to a boolean value which controls whether the pure Perl
1192 implementation of C<Data::Dumper> is used. The C<Data::Dumper> module is
1193 a dual implementation, with almost all functionality written in both
1194 pure Perl and also in XS ('C'). Since the XS version is much faster, it
1195 will always be used if possible. This option lets you override the
1196 default behavior, usually for testing purposes only. Default is 0, which
1197 means the XS implementation will be used if possible.
1201 $Data::Dumper::Sortkeys I<or> $I<OBJ>->Sortkeys(I<[NEWVAL]>)
1203 Can be set to a boolean value to control whether hash keys are dumped in
1204 sorted order. A true value will cause the keys of all hashes to be
1205 dumped in Perl's default sort order. Can also be set to a subroutine
1206 reference which will be called for each hash that is dumped. In this
1207 case C<Data::Dumper> will call the subroutine once for each hash,
1208 passing it the reference of the hash. The purpose of the subroutine is
1209 to return a reference to an array of the keys that will be dumped, in
1210 the order that they should be dumped. Using this feature, you can
1211 control both the order of the keys, and which keys are actually used. In
1212 other words, this subroutine acts as a filter by which you can exclude
1213 certain keys from being dumped. Default is 0, which means that hash keys
1218 $Data::Dumper::Deparse I<or> $I<OBJ>->Deparse(I<[NEWVAL]>)
1220 Can be set to a boolean value to control whether code references are
1221 turned into perl source code. If set to a true value, C<B::Deparse>
1222 will be used to get the source of the code reference. In older versions,
1223 using this option imposed a significant performance penalty when dumping
1224 parts of a data structure other than code references, but that is no
1227 Caution : use this option only if you know that your coderefs will be
1228 properly reconstructed by C<B::Deparse>.
1232 $Data::Dumper::Sparseseen I<or> $I<OBJ>->Sparseseen(I<[NEWVAL]>)
1234 By default, Data::Dumper builds up the "seen" hash of scalars that
1235 it has encountered during serialization. This is very expensive.
1236 This seen hash is necessary to support and even just detect circular
1237 references. It is exposed to the user via the C<Seen()> call both
1238 for writing and reading.
1240 If you, as a user, do not need explicit access to the "seen" hash,
1241 then you can set the C<Sparseseen> option to allow Data::Dumper
1242 to eschew building the "seen" hash for scalars that are known not
1243 to possess more than one reference. This speeds up serialization
1244 considerably if you use the XS implementation.
1246 Note: If you turn on C<Sparseseen>, then you must not rely on the
1247 content of the seen hash since its contents will be an
1248 implementation detail!
1262 Run these code snippets to get a quick feel for the behavior of this
1263 module. When you are through with these examples, you may want to
1264 add or change the various configuration variables described above,
1265 to see their behavior. (See the testsuite in the Data::Dumper
1266 distribution for more examples.)
1272 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
1274 package Fuz; # a weird REF-REF-SCALAR object
1275 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
1280 $boo = [ 1, [], "abcd", \*foo,
1281 {1 => 'a', 023 => 'b', 0x45 => 'c'},
1282 \\"p\q\'r", $foo, $fuz];
1288 $bar = eval(Dumper($boo));
1290 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
1292 $Data::Dumper::Terse = 1; # don't output names where feasible
1293 $Data::Dumper::Indent = 0; # turn off all pretty print
1294 print Dumper($boo), "\n";
1296 $Data::Dumper::Indent = 1; # mild pretty print
1299 $Data::Dumper::Indent = 3; # pretty print with array indices
1302 $Data::Dumper::Useqq = 1; # print strings in double quotes
1305 $Data::Dumper::Pair = " : "; # specify hash key/value separator
1310 # recursive structures
1320 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
1323 $Data::Dumper::Purity = 1; # fill in the holes for eval
1324 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
1325 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
1328 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
1329 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1332 $Data::Dumper::Purity = 0; # avoid cross-refs
1333 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1345 print Data::Dumper->Dump([$f], [qw(f)]);
1347 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
1348 print Data::Dumper->Dump([$f], [qw(f)]);
1352 # object-oriented usage
1355 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
1356 $d->Seen({'*c' => $c}); # stash a ref without printing it
1359 $d->Reset->Purity(0); # empty the seen cache
1360 print join "----\n", $d->Dump;
1368 sub new { bless { state => 'awake' }, shift }
1371 print STDERR "preparing to sleep\n";
1372 $s->{state} = 'asleep';
1373 return bless $s, 'Foo::ZZZ';
1379 print STDERR "waking up\n";
1380 $s->{state} = 'awake';
1381 return bless $s, 'Foo';
1387 $b = Data::Dumper->new([$a], ['c']);
1388 $b->Freezer('Freeze');
1389 $b->Toaster('Thaw');
1393 print Data::Dumper->Dump([$d], ['d']);
1397 # symbol substitution (useful for recreating CODE refs)
1400 sub foo { print "foo speaking\n" }
1403 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1404 $d->Seen({ '*foo' => \&foo });
1409 # sorting and filtering hash keys
1412 $Data::Dumper::Sortkeys = \&my_filter;
1413 my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' };
1414 my $bar = { %$foo };
1415 my $baz = { reverse %$foo };
1416 print Dumper [ $foo, $bar, $baz ];
1420 # return an array ref containing the hash keys to dump
1421 # in the order that you want them to be dumped
1423 # Sort the keys of %$foo in reverse numeric order
1424 $hash eq $foo ? (sort {$b <=> $a} keys %$hash) :
1425 # Only dump the odd number keys of %$bar
1426 $hash eq $bar ? (grep {$_ % 2} keys %$hash) :
1427 # Sort keys in default order for all other hashes
1434 Due to limitations of Perl subroutine call semantics, you cannot pass an
1435 array or hash. Prepend it with a C<\> to pass its reference instead. This
1436 will be remedied in time, now that Perl has subroutine prototypes.
1437 For now, you need to use the extended usage form, and prepend the
1438 name with a C<*> to output it as a hash or array.
1440 C<Data::Dumper> cheats with CODE references. If a code reference is
1441 encountered in the structure being processed (and if you haven't set
1442 the C<Deparse> flag), an anonymous subroutine that
1443 contains the string '"DUMMY"' will be inserted in its place, and a warning
1444 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1445 in mind that the anonymous sub that gets created is just a placeholder.
1446 Even using the C<Deparse> flag will in some cases produce results that
1447 behave differently after being passed to C<eval>; see the documentation
1450 SCALAR objects have the weirdest looking C<bless> workaround.
1452 Pure Perl version of C<Data::Dumper> escapes UTF-8 strings correctly
1453 only in Perl 5.8.0 and later.
1457 Starting from Perl 5.8.1 different runs of Perl will have different
1458 ordering of hash keys. The change was done for greater security,
1459 see L<perlsec/"Algorithmic Complexity Attacks">. This means that
1460 different runs of Perl will have different Data::Dumper outputs if
1461 the data contains hashes. If you need to have identical Data::Dumper
1462 outputs from different runs of Perl, use the environment variable
1463 PERL_HASH_SEED, see L<perlrun/PERL_HASH_SEED>. Using this restores
1464 the old (platform-specific) ordering: an even prettier solution might
1465 be to use the C<Sortkeys> filter of Data::Dumper.
1469 Gurusamy Sarathy gsar@activestate.com
1471 Copyright (c) 1996-2017 Gurusamy Sarathy. All rights reserved.
1472 This program is free software; you can redistribute it and/or
1473 modify it under the same terms as Perl itself.