4 # convert perl data structures into perl syntax suitable for both printing
7 # Documentation at the __END__
13 $VERSION = '2.137'; # Don't forget to set version and release
27 @EXPORT_OK = qw(DumperX);
29 # if run under miniperl, or otherwise lacking dynamic loading,
30 # XSLoader should be attempted to load, or the pure perl flag
31 # toggled on load failure.
34 XSLoader::load( 'Data::Dumper' );
40 # module vars and their defaults
41 $Indent = 2 unless defined $Indent;
42 $Purity = 0 unless defined $Purity;
43 $Pad = "" unless defined $Pad;
44 $Varname = "VAR" unless defined $Varname;
45 $Useqq = 0 unless defined $Useqq;
46 $Terse = 0 unless defined $Terse;
47 $Freezer = "" unless defined $Freezer;
48 $Toaster = "" unless defined $Toaster;
49 $Deepcopy = 0 unless defined $Deepcopy;
50 $Quotekeys = 1 unless defined $Quotekeys;
51 $Bless = "bless" unless defined $Bless;
52 #$Expdepth = 0 unless defined $Expdepth;
53 $Maxdepth = 0 unless defined $Maxdepth;
54 $Pair = ' => ' unless defined $Pair;
55 $Useperl = 0 unless defined $Useperl;
56 $Sortkeys = 0 unless defined $Sortkeys;
57 $Deparse = 0 unless defined $Deparse;
58 $Sparseseen = 0 unless defined $Sparseseen;
61 # expects an arrayref of values to be dumped.
62 # can optionally pass an arrayref of names for the values.
63 # names must have leading $ sign stripped. begin the name with *
64 # to cause output of arrays and hashes rather than refs.
69 croak "Usage: PACKAGE->new(ARRAYREF, [ARRAYREF])"
70 unless (defined($v) && (ref($v) eq 'ARRAY'));
71 $n = [] unless (defined($n) && (ref($n) eq 'ARRAY'));
74 level => 0, # current recursive depth
75 indent => $Indent, # various styles of indenting
76 pad => $Pad, # all lines prefixed by this string
77 xpad => "", # padding-per-level
78 apad => "", # added padding for hash keys n such
79 sep => "", # list separator
80 pair => $Pair, # hash key/value separator: defaults to ' => '
81 seen => {}, # local (nested) refs (id => [name, val])
82 todump => $v, # values to dump []
83 names => $n, # optional names for values []
84 varname => $Varname, # prefix to use for tagging nameless ones
85 purity => $Purity, # degree to which output is evalable
86 useqq => $Useqq, # use "" for strings (backslashitis ensues)
87 terse => $Terse, # avoid name output (where feasible)
88 freezer => $Freezer, # name of Freezer method for objects
89 toaster => $Toaster, # name of method to revive objects
90 deepcopy => $Deepcopy, # dont cross-ref, except to stop recursion
91 quotekeys => $Quotekeys, # quote hash keys
92 'bless' => $Bless, # keyword to use for "bless"
93 # expdepth => $Expdepth, # cutoff depth for explicit dumping
94 maxdepth => $Maxdepth, # depth beyond which we give up
95 useperl => $Useperl, # use the pure Perl implementation
96 sortkeys => $Sortkeys, # flag or filter for sorting hash keys
97 deparse => $Deparse, # use B::Deparse for coderefs
98 noseen => $Sparseseen, # do not populate the seen hash unless necessary
105 return bless($s, $c);
108 # Packed numeric addresses take less memory. Plus pack is faster than sprintf
110 # Most users of current versions of Data::Dumper will be 5.008 or later.
111 # Anyone on 5.6.1 and 5.6.2 upgrading will be rare (particularly judging by
112 # the bug reports from users on those platforms), so for the common case avoid
113 # complexity, and avoid even compiling the unneeded code.
115 sub init_refaddr_format {
119 require Scalar::Util;
120 pack "J", Scalar::Util::refaddr(shift);
125 no warnings 'redefine';
127 sub init_refaddr_format {
129 my $f = $Config::Config{uvxformat};
131 $refaddr_format = "0x%" . $f;
135 require Scalar::Util;
136 sprintf $refaddr_format, Scalar::Util::refaddr(shift);
144 # add-to or query the table of already seen references
148 if (defined($g) && (ref($g) eq 'HASH')) {
149 init_refaddr_format();
151 while (($k, $v) = each %$g) {
152 if (defined $v and ref $v) {
153 $id = format_refaddr($v);
154 if ($k =~ /^[*](.*)$/) {
155 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
156 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
157 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
160 elsif ($k !~ /^\$/) {
163 $s->{seen}{$id} = [$k, $v];
166 carp "Only refs supported, ignoring non-ref item \$$k";
172 return map { @$_ } values %{$s->{seen}};
177 # set or query the values to be dumped
181 if (defined($v) && (ref($v) eq 'ARRAY')) {
182 $s->{todump} = [@$v]; # make a copy
186 return @{$s->{todump}};
191 # set or query the names of the values to be dumped
195 if (defined($n) && (ref($n) eq 'ARRAY')) {
196 $s->{names} = [@$n]; # make a copy
200 return @{$s->{names}};
208 unless $Data::Dumper::Useperl || (ref($_[0]) && $_[0]->{useperl}) ||
209 $Data::Dumper::Useqq || (ref($_[0]) && $_[0]->{useqq}) ||
210 $Data::Dumper::Deparse || (ref($_[0]) && $_[0]->{deparse});
215 # dump the refs in the current dumper object.
216 # expects same args as new() if called via package name.
220 my(@out, $val, $name);
223 init_refaddr_format();
225 $s = $s->new(@_) unless ref $s;
227 for $val (@{$s->{todump}}) {
230 $name = $s->{names}[$i++];
232 if ($name =~ /^[*](.*)$/) {
234 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
235 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
236 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
243 elsif ($name !~ /^\$/) {
244 $name = "\$" . $name;
248 $name = "\$" . $s->{varname} . $i;
253 local($s->{apad}) = $s->{apad};
254 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2 and !$s->{terse};
255 $valstr = $s->_dump($val, $name);
258 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
259 $out .= $s->{pad} . $valstr . $s->{sep};
260 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
261 . ';' . $s->{sep} if @post;
265 return wantarray ? @out : join('', @out);
268 # wrap string in single quotes (escaping if needed)
271 $val =~ s/([\\\'])/\\$1/g;
272 return "'" . $val . "'";
275 # Old Perls (5.14-) have trouble resetting vstring magic when it is no
277 use constant _bad_vsmg => defined &_vstring && (_vstring(~v0)||'') eq "v0";
280 # twist, toil and turn;
281 # and recurse, of course.
282 # sometimes sordidly;
283 # and curse if no recourse.
286 my($s, $val, $name) = @_;
288 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
295 # Call the freezer method if it's specified and the object has the
296 # method. Trap errors and warn() instead of die()ing, like the XS
298 my $freezer = $s->{freezer};
299 if ($freezer and UNIVERSAL::can($val, $freezer)) {
300 eval { $val->$freezer() };
301 warn "WARNING(Freezer method call failed): $@" if $@;
304 require Scalar::Util;
305 $realpack = Scalar::Util::blessed($val);
306 $realtype = $realpack ? Scalar::Util::reftype($val) : ref $val;
307 $id = format_refaddr($val);
309 # if it has a name, we need to either look it up, or keep a tab
310 # on it so we know when we hit it later
311 if (defined($name) and length($name)) {
312 # keep a tab on it so that we dont fall into recursive pit
313 if (exists $s->{seen}{$id}) {
314 # if ($s->{expdepth} < $s->{level}) {
315 if ($s->{purity} and $s->{level} > 0) {
316 $out = ($realtype eq 'HASH') ? '{}' :
317 ($realtype eq 'ARRAY') ? '[]' :
319 push @post, $name . " = " . $s->{seen}{$id}[0];
322 $out = $s->{seen}{$id}[0];
323 if ($name =~ /^([\@\%])/) {
325 if ($out =~ /^\\$start/) {
326 $out = substr($out, 1);
329 $out = $start . '{' . $out . '}';
338 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
339 ($realtype eq 'CODE' and
340 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
347 if ( $realpack and ($] >= 5.009005 ? re::is_regexp($val) : $realpack eq 'Regexp') ) {
349 $no_bless = $realpack eq 'Regexp';
352 # If purity is not set and maxdepth is set, then check depth:
353 # if we have reached maximum depth, return the string
354 # representation of the thing we are currently examining
355 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
357 and $s->{maxdepth} > 0
358 and $s->{level} >= $s->{maxdepth})
363 # we have a blessed ref
364 if ($realpack and !$no_bless) {
365 $out = $s->{'bless'} . '( ';
366 $blesspad = $s->{apad};
367 $s->{apad} .= ' ' if ($s->{indent} >= 2);
371 $ipad = $s->{xpad} x $s->{level};
375 # This really sucks, re:regexp_pattern is in ext/re/re.xs and not in
376 # universal.c, and even worse we cant just require that re to be loaded
377 # we *have* to use() it.
378 # We should probably move it to universal.c for 5.10.1 and fix this.
379 # Currently we only use re::regexp_pattern when the re is blessed into another
380 # package. This has the disadvantage of meaning that a DD dump won't round trip
381 # as the pattern will be repeatedly wrapped with the same modifiers.
382 # This is an aesthetic issue so we will leave it for now, but we could use
383 # regexp_pattern() in list context to get the modifiers separately.
384 # But since this means loading the full debugging engine in process we wont
385 # bother unless its necessary for accuracy.
386 if (($realpack ne 'Regexp') && defined(*re::regexp_pattern{CODE})) {
387 $pat = re::regexp_pattern($val);
391 $pat =~ s <(\\.)|/> { $1 || '\\/' }ge;
394 elsif ($realtype eq 'SCALAR' || $realtype eq 'REF'
395 || $realtype eq 'VSTRING') {
397 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
400 $out .= '\\' . $s->_dump($$val, "\${$name}");
403 elsif ($realtype eq 'GLOB') {
404 $out .= '\\' . $s->_dump($$val, "*{$name}");
406 elsif ($realtype eq 'ARRAY') {
409 $out .= ($name =~ /^\@/) ? '(' : '[';
410 $pad = $s->{sep} . $s->{pad} . $s->{apad};
411 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
412 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
413 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
414 ($mname = $name . '->');
415 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
417 $sname = $mname . '[' . $i . ']';
418 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
419 $out .= $pad . $ipad . $s->_dump($v, $sname);
420 $out .= "," if $i++ < $#$val;
422 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
423 $out .= ($name =~ /^\@/) ? ')' : ']';
425 elsif ($realtype eq 'HASH') {
426 my($k, $v, $pad, $lpad, $mname, $pair);
427 $out .= ($name =~ /^\%/) ? '(' : '{';
428 $pad = $s->{sep} . $s->{pad} . $s->{apad};
431 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
432 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
433 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
434 ($mname = $name . '->');
435 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
436 my ($sortkeys, $keys, $key) = ("$s->{sortkeys}");
438 if (ref($s->{sortkeys}) eq 'CODE') {
439 $keys = $s->{sortkeys}($val);
440 unless (ref($keys) eq 'ARRAY') {
441 carp "Sortkeys subroutine did not return ARRAYREF";
446 $keys = [ sort keys %$val ];
450 # Ensure hash iterator is reset
453 while (($k, $v) = ! $sortkeys ? (each %$val) :
454 @$keys ? ($key = shift(@$keys), $val->{$key}) :
457 my $nk = $s->_dump($k, "");
458 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
459 $sname = $mname . '{' . $nk . '}';
460 $out .= $pad . $ipad . $nk . $pair;
462 # temporarily alter apad
463 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
464 $out .= $s->_dump($val->{$k}, $sname) . ",";
465 $s->{apad} = $lpad if $s->{indent} >= 2;
467 if (substr($out, -1) eq ',') {
469 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
471 $out .= ($name =~ /^\%/) ? ')' : '}';
473 elsif ($realtype eq 'CODE') {
476 my $sub = 'sub ' . (B::Deparse->new)->coderef2text($val);
477 $pad = $s->{sep} . $s->{pad} . $s->{apad} . $s->{xpad} x ($s->{level} - 1);
478 $sub =~ s/\n/$pad/gse;
481 $out .= 'sub { "DUMMY" }';
482 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
486 croak "Can\'t handle $realtype type.";
489 if ($realpack and !$no_bless) { # we have a blessed ref
490 $out .= ', ' . _quote($realpack) . ' )';
491 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
492 $s->{apad} = $blesspad;
497 else { # simple scalar
501 # first, catalog the scalar
503 $id = format_refaddr($ref);
504 if (exists $s->{seen}{$id}) {
505 if ($s->{seen}{$id}[2]) {
506 $out = $s->{seen}{$id}[0];
512 #warn "[>\\$name]\n";
513 $s->{seen}{$id} = ["\\$name", $ref];
517 if (ref($ref) eq 'GLOB') { # glob
518 my $name = substr($val, 1);
519 if ($name =~ /^[A-Za-z_][\w:]*$/ && $name ne 'main::') {
520 $name =~ s/^main::/::/;
525 $name eq 'main::' || $] < 5.007 && $name eq "main::\0"
530 $sname = '{' . $sname . '}';
534 local ($s->{level}) = 0;
535 for $k (qw(SCALAR ARRAY HASH)) {
536 my $gval = *$val{$k};
537 next unless defined $gval;
538 next if $k eq "SCALAR" && ! defined $$gval; # always there
540 # _dump can push into @post, so we hold our place using $postlen
541 my $postlen = scalar @post;
542 $post[$postlen] = "\*$sname = ";
543 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
544 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
547 $out .= '*' . $sname;
549 elsif (!defined($val)) {
552 elsif (defined &_vstring and $v = _vstring($val)
553 and !_bad_vsmg || eval $v eq $val) {
556 elsif (!defined &_vstring
557 and ref $ref eq 'VSTRING' || eval{Scalar::Util::isvstring($val)}) {
558 $out .= sprintf "%vd", $val;
560 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})\z/) { # safe decimal number
564 if ($s->{useqq} or $val =~ tr/\0-\377//c) {
565 # Fall back to qq if there's Unicode
566 $out .= qquote($val, $s->{useqq});
569 $out .= _quote($val);
574 # if we made it this far, $id was added to seen list at current
575 # level, so remove it to get deep copies
576 if ($s->{deepcopy}) {
577 delete($s->{seen}{$id});
580 $s->{seen}{$id}[2] = 1;
587 # non-OO style of earlier version
590 return Data::Dumper->Dump([@_]);
595 return Data::Dumper->Dumpxs([@_], []);
598 sub Dumpf { return Data::Dumper->Dump(@_) }
600 sub Dumpp { print Data::Dumper->Dump(@_) }
603 # reset the "seen" cache
632 defined($v) ? (($s->{pair} = $v), return $s) : $s->{pair};
637 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
642 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
647 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
652 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
657 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
662 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
667 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
672 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
677 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
682 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
687 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
692 defined($v) ? (($s->{'useperl'} = $v), return $s) : $s->{'useperl'};
697 defined($v) ? (($s->{'sortkeys'} = $v), return $s) : $s->{'sortkeys'};
702 defined($v) ? (($s->{'deparse'} = $v), return $s) : $s->{'deparse'};
707 defined($v) ? (($s->{'noseen'} = $v), return $s) : $s->{'noseen'};
710 # used by qquote below
721 # put a string value in double quotes
724 s/([\\\"\@\$])/\\$1/g;
725 my $bytes; { use bytes; $bytes = length }
726 s/([^\x00-\x7f])/'\x{'.sprintf("%x",ord($1)).'}'/ge if $bytes > length;
727 return qq("$_") unless
728 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
730 my $high = shift || "";
731 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
733 if (ord('^')==94) { # ascii
734 # no need for 3 digits in escape for these
735 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
736 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
737 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
738 if ($high eq "iso8859") {
739 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
740 } elsif ($high eq "utf8") {
742 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
743 } elsif ($high eq "8bit") {
746 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
747 s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
751 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
752 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
753 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
754 {'\\'.sprintf('%03o',ord($1))}eg;
760 # helper sub to sort hash keys in Perl < 5.8.0 where we don't have
761 # access to sortsv() from XS
762 sub _sortkeys { [ sort keys %{$_[0]} ] }
769 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
775 # simple procedural interface
776 print Dumper($foo, $bar);
778 # extended usage with names
779 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
781 # configuration variables
783 local $Data::Dumper::Purity = 1;
784 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
788 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
792 $d->Purity(1)->Terse(1)->Deepcopy(1);
798 Given a list of scalars or reference variables, writes out their contents in
799 perl syntax. The references can also be objects. The content of each
800 variable is output in a single Perl statement. Handles self-referential
801 structures correctly.
803 The return value can be C<eval>ed to get back an identical copy of the
804 original reference structure.
806 Any references that are the same as one of those passed in will be named
807 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
808 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
809 notation. You can specify names for individual values to be dumped if you
810 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
811 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
814 The default output of self-referential structures can be C<eval>ed, but the
815 nested references to C<$VAR>I<n> will be undefined, since a recursive
816 structure cannot be constructed using one Perl statement. You should set the
817 C<Purity> flag to 1 to get additional statements that will correctly fill in
818 these references. Moreover, if C<eval>ed when strictures are in effect,
819 you need to ensure that any variables it accesses are previously declared.
821 In the extended usage form, the references to be dumped can be given
822 user-specified names. If a name begins with a C<*>, the output will
823 describe the dereferenced type of the supplied reference for hashes and
824 arrays, and coderefs. Output of names will be avoided where possible if
825 the C<Terse> flag is set.
827 In many cases, methods that are used to set the internal state of the
828 object will return the object itself, so method calls can be conveniently
831 Several styles of output are possible, all controlled by setting
832 the C<Indent> flag. See L<Configuration Variables or Methods> below
840 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
842 Returns a newly created C<Data::Dumper> object. The first argument is an
843 anonymous array of values to be dumped. The optional second argument is an
844 anonymous array of names for the values. The names need not have a leading
845 C<$> sign, and must be comprised of alphanumeric characters. You can begin
846 a name with a C<*> to specify that the dereferenced type must be dumped
847 instead of the reference itself, for ARRAY and HASH references.
849 The prefix specified by C<$Data::Dumper::Varname> will be used with a
850 numeric suffix if the name for a value is undefined.
852 Data::Dumper will catalog all references encountered while dumping the
853 values. Cross-references (in the form of names of substructures in perl
854 syntax) will be inserted at all possible points, preserving any structural
855 interdependencies in the original set of values. Structure traversal is
856 depth-first, and proceeds in order from the first supplied value to
859 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
861 Returns the stringified form of the values stored in the object (preserving
862 the order in which they were supplied to C<new>), subject to the
863 configuration options below. In a list context, it returns a list
864 of strings corresponding to the supplied values.
866 The second form, for convenience, simply calls the C<new> method on its
867 arguments before dumping the object immediately.
869 =item I<$OBJ>->Seen(I<[HASHREF]>)
871 Queries or adds to the internal table of already encountered references.
872 You must use C<Reset> to explicitly clear the table if needed. Such
873 references are not dumped; instead, their names are inserted wherever they
874 are encountered subsequently. This is useful especially for properly
875 dumping subroutine references.
877 Expects an anonymous hash of name => value pairs. Same rules apply for names
878 as in C<new>. If no argument is supplied, will return the "seen" list of
879 name => value pairs, in a list context. Otherwise, returns the object
882 =item I<$OBJ>->Values(I<[ARRAYREF]>)
884 Queries or replaces the internal array of values that will be dumped.
885 When called without arguments, returns the values. Otherwise, returns the
888 =item I<$OBJ>->Names(I<[ARRAYREF]>)
890 Queries or replaces the internal array of user supplied names for the values
891 that will be dumped. When called without arguments, returns the names.
892 Otherwise, returns the object itself.
896 Clears the internal table of "seen" references and returns the object
905 =item Dumper(I<LIST>)
907 Returns the stringified form of the values in the list, subject to the
908 configuration options below. The values will be named C<$VAR>I<n> in the
909 output, where I<n> is a numeric suffix. Will return a list of strings
914 =head2 Configuration Variables or Methods
916 Several configuration variables can be used to control the kind of output
917 generated when using the procedural interface. These variables are usually
918 C<local>ized in a block so that other parts of the code are not affected by
921 These variables determine the default state of the object created by calling
922 the C<new> method, but cannot be used to alter the state of the object
923 thereafter. The equivalent method names should be used instead to query
924 or set the internal state of the object.
926 The method forms return the object itself when called with arguments,
927 so that they can be chained together nicely.
933 $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
935 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
936 spews output without any newlines, indentation, or spaces between list
937 items. It is the most compact format possible that can still be called
938 valid perl. Style 1 outputs a readable form with newlines but no fancy
939 indentation (each level in the structure is simply indented by a fixed
940 amount of whitespace). Style 2 (the default) outputs a very readable form
941 which takes into account the length of hash keys (so the hash value lines
942 up). Style 3 is like style 2, but also annotates the elements of arrays
943 with their index (but the comment is on its own line, so array output
944 consumes twice the number of lines). Style 2 is the default.
948 $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
950 Controls the degree to which the output can be C<eval>ed to recreate the
951 supplied reference structures. Setting it to 1 will output additional perl
952 statements that will correctly recreate nested references. The default is
957 $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
959 Specifies the string that will be prefixed to every line of the output.
960 Empty string by default.
964 $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
966 Contains the prefix to use for tagging variable names in the output. The
971 $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
973 When set, enables the use of double quotes for representing string values.
974 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
975 characters will be backslashed, and unprintable characters will be output as
976 quoted octal integers. Since setting this variable imposes a performance
977 penalty, the default is 0. C<Dump()> will run slower if this flag is set,
978 since the fast XSUB implementation doesn't support it yet.
982 $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
984 When set, Data::Dumper will emit single, non-self-referential values as
985 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
986 will be avoided where possible, but be advised that such output may not
987 always be parseable by C<eval>.
991 $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
993 Can be set to a method name, or to an empty string to disable the feature.
994 Data::Dumper will invoke that method via the object before attempting to
995 stringify it. This method can alter the contents of the object (if, for
996 instance, it contains data allocated from C), and even rebless it in a
997 different package. The client is responsible for making sure the specified
998 method can be called via the object, and that the object ends up containing
999 only perl data types after the method has been called. Defaults to an empty
1002 If an object does not support the method specified (determined using
1003 UNIVERSAL::can()) then the call will be skipped. If the method dies a
1004 warning will be generated.
1008 $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
1010 Can be set to a method name, or to an empty string to disable the feature.
1011 Data::Dumper will emit a method call for any objects that are to be dumped
1012 using the syntax C<bless(DATA, CLASS)-E<gt>METHOD()>. Note that this means that
1013 the method specified will have to perform any modifications required on the
1014 object (like creating new state within it, and/or reblessing it in a
1015 different package) and then return it. The client is responsible for making
1016 sure the method can be called via the object, and that it returns a valid
1017 object. Defaults to an empty string.
1021 $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
1023 Can be set to a boolean value to enable deep copies of structures.
1024 Cross-referencing will then only be done when absolutely essential
1025 (i.e., to break reference cycles). Default is 0.
1029 $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
1031 Can be set to a boolean value to control whether hash keys are quoted.
1032 A false value will avoid quoting hash keys when it looks like a simple
1033 string. Default is 1, which will always enclose hash keys in quotes.
1037 $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
1039 Can be set to a string that specifies an alternative to the C<bless>
1040 builtin operator used to create objects. A function with the specified
1041 name should exist, and should accept the same arguments as the builtin.
1042 Default is C<bless>.
1046 $Data::Dumper::Pair I<or> $I<OBJ>->Pair(I<[NEWVAL]>)
1048 Can be set to a string that specifies the separator between hash keys
1049 and values. To dump nested hash, array and scalar values to JavaScript,
1050 use: C<$Data::Dumper::Pair = ' : ';>. Implementing C<bless> in JavaScript
1051 is left as an exercise for the reader.
1052 A function with the specified name exists, and accepts the same arguments
1055 Default is: C< =E<gt> >.
1059 $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
1061 Can be set to a positive integer that specifies the depth beyond which
1062 we don't venture into a structure. Has no effect when
1063 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
1064 want to see more than enough). Default is 0, which means there is
1069 $Data::Dumper::Useperl I<or> $I<OBJ>->Useperl(I<[NEWVAL]>)
1071 Can be set to a boolean value which controls whether the pure Perl
1072 implementation of C<Data::Dumper> is used. The C<Data::Dumper> module is
1073 a dual implementation, with almost all functionality written in both
1074 pure Perl and also in XS ('C'). Since the XS version is much faster, it
1075 will always be used if possible. This option lets you override the
1076 default behavior, usually for testing purposes only. Default is 0, which
1077 means the XS implementation will be used if possible.
1081 $Data::Dumper::Sortkeys I<or> $I<OBJ>->Sortkeys(I<[NEWVAL]>)
1083 Can be set to a boolean value to control whether hash keys are dumped in
1084 sorted order. A true value will cause the keys of all hashes to be
1085 dumped in Perl's default sort order. Can also be set to a subroutine
1086 reference which will be called for each hash that is dumped. In this
1087 case C<Data::Dumper> will call the subroutine once for each hash,
1088 passing it the reference of the hash. The purpose of the subroutine is
1089 to return a reference to an array of the keys that will be dumped, in
1090 the order that they should be dumped. Using this feature, you can
1091 control both the order of the keys, and which keys are actually used. In
1092 other words, this subroutine acts as a filter by which you can exclude
1093 certain keys from being dumped. Default is 0, which means that hash keys
1098 $Data::Dumper::Deparse I<or> $I<OBJ>->Deparse(I<[NEWVAL]>)
1100 Can be set to a boolean value to control whether code references are
1101 turned into perl source code. If set to a true value, C<B::Deparse>
1102 will be used to get the source of the code reference. Using this option
1103 will force using the Perl implementation of the dumper, since the fast
1104 XSUB implementation doesn't support it.
1106 Caution : use this option only if you know that your coderefs will be
1107 properly reconstructed by C<B::Deparse>.
1111 $Data::Dumper::Sparseseen I<or> $I<OBJ>->Sparseseen(I<[NEWVAL]>)
1113 By default, Data::Dumper builds up the "seen" hash of scalars that
1114 it has encountered during serialization. This is very expensive.
1115 This seen hash is necessary to support and even just detect circular
1116 references. It is exposed to the user via the C<Seen()> call both
1117 for writing and reading.
1119 If you, as a user, do not need explicit access to the "seen" hash,
1120 then you can set the C<Sparseseen> option to allow Data::Dumper
1121 to eschew building the "seen" hash for scalars that are known not
1122 to possess more than one reference. This speeds up serialization
1123 considerably if you use the XS implementation.
1125 Note: If you turn on C<Sparseseen>, then you must not rely on the
1126 content of the seen hash since its contents will be an
1127 implementation detail!
1141 Run these code snippets to get a quick feel for the behavior of this
1142 module. When you are through with these examples, you may want to
1143 add or change the various configuration variables described above,
1144 to see their behavior. (See the testsuite in the Data::Dumper
1145 distribution for more examples.)
1151 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
1153 package Fuz; # a weird REF-REF-SCALAR object
1154 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
1159 $boo = [ 1, [], "abcd", \*foo,
1160 {1 => 'a', 023 => 'b', 0x45 => 'c'},
1161 \\"p\q\'r", $foo, $fuz];
1167 $bar = eval(Dumper($boo));
1169 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
1171 $Data::Dumper::Terse = 1; # don't output names where feasible
1172 $Data::Dumper::Indent = 0; # turn off all pretty print
1173 print Dumper($boo), "\n";
1175 $Data::Dumper::Indent = 1; # mild pretty print
1178 $Data::Dumper::Indent = 3; # pretty print with array indices
1181 $Data::Dumper::Useqq = 1; # print strings in double quotes
1184 $Data::Dumper::Pair = " : "; # specify hash key/value separator
1189 # recursive structures
1199 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
1202 $Data::Dumper::Purity = 1; # fill in the holes for eval
1203 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
1204 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
1207 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
1208 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1211 $Data::Dumper::Purity = 0; # avoid cross-refs
1212 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1224 print Data::Dumper->Dump([$f], [qw(f)]);
1226 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
1227 print Data::Dumper->Dump([$f], [qw(f)]);
1231 # object-oriented usage
1234 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
1235 $d->Seen({'*c' => $c}); # stash a ref without printing it
1238 $d->Reset->Purity(0); # empty the seen cache
1239 print join "----\n", $d->Dump;
1247 sub new { bless { state => 'awake' }, shift }
1250 print STDERR "preparing to sleep\n";
1251 $s->{state} = 'asleep';
1252 return bless $s, 'Foo::ZZZ';
1258 print STDERR "waking up\n";
1259 $s->{state} = 'awake';
1260 return bless $s, 'Foo';
1266 $b = Data::Dumper->new([$a], ['c']);
1267 $b->Freezer('Freeze');
1268 $b->Toaster('Thaw');
1272 print Data::Dumper->Dump([$d], ['d']);
1276 # symbol substitution (useful for recreating CODE refs)
1279 sub foo { print "foo speaking\n" }
1282 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1283 $d->Seen({ '*foo' => \&foo });
1288 # sorting and filtering hash keys
1291 $Data::Dumper::Sortkeys = \&my_filter;
1292 my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' };
1293 my $bar = { %$foo };
1294 my $baz = { reverse %$foo };
1295 print Dumper [ $foo, $bar, $baz ];
1299 # return an array ref containing the hash keys to dump
1300 # in the order that you want them to be dumped
1302 # Sort the keys of %$foo in reverse numeric order
1303 $hash eq $foo ? (sort {$b <=> $a} keys %$hash) :
1304 # Only dump the odd number keys of %$bar
1305 $hash eq $bar ? (grep {$_ % 2} keys %$hash) :
1306 # Sort keys in default order for all other hashes
1313 Due to limitations of Perl subroutine call semantics, you cannot pass an
1314 array or hash. Prepend it with a C<\> to pass its reference instead. This
1315 will be remedied in time, now that Perl has subroutine prototypes.
1316 For now, you need to use the extended usage form, and prepend the
1317 name with a C<*> to output it as a hash or array.
1319 C<Data::Dumper> cheats with CODE references. If a code reference is
1320 encountered in the structure being processed (and if you haven't set
1321 the C<Deparse> flag), an anonymous subroutine that
1322 contains the string '"DUMMY"' will be inserted in its place, and a warning
1323 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1324 in mind that the anonymous sub that gets created is just a placeholder.
1325 Someday, perl will have a switch to cache-on-demand the string
1326 representation of a compiled piece of code, I hope. If you have prior
1327 knowledge of all the code refs that your data structures are likely
1328 to have, you can use the C<Seen> method to pre-seed the internal reference
1329 table and make the dumped output point to them, instead. See L</EXAMPLES>
1332 The C<Useqq> and C<Deparse> flags makes Dump() run slower, since the
1333 XSUB implementation does not support them.
1335 SCALAR objects have the weirdest looking C<bless> workaround.
1337 Pure Perl version of C<Data::Dumper> escapes UTF-8 strings correctly
1338 only in Perl 5.8.0 and later.
1342 Starting from Perl 5.8.1 different runs of Perl will have different
1343 ordering of hash keys. The change was done for greater security,
1344 see L<perlsec/"Algorithmic Complexity Attacks">. This means that
1345 different runs of Perl will have different Data::Dumper outputs if
1346 the data contains hashes. If you need to have identical Data::Dumper
1347 outputs from different runs of Perl, use the environment variable
1348 PERL_HASH_SEED, see L<perlrun/PERL_HASH_SEED>. Using this restores
1349 the old (platform-specific) ordering: an even prettier solution might
1350 be to use the C<Sortkeys> filter of Data::Dumper.
1354 Gurusamy Sarathy gsar@activestate.com
1356 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1357 This program is free software; you can redistribute it and/or
1358 modify it under the same terms as Perl itself.
1362 Version 2.137 (October 22 2012)