4 # convert perl data structures into perl syntax suitable for both printing
7 # Documentation at the __END__
12 $VERSION = '2.121_18';
25 @EXPORT_OK = qw(DumperX);
27 # if run under miniperl, or otherwise lacking dynamic loading,
28 # XSLoader should be attempted to load, or the pure perl flag
29 # toggled on load failure.
36 XSLoader::load( 'Data::Dumper' ) unless $Useperl;
38 # module vars and their defaults
39 $Indent = 2 unless defined $Indent;
40 $Purity = 0 unless defined $Purity;
41 $Pad = "" unless defined $Pad;
42 $Varname = "VAR" unless defined $Varname;
43 $Useqq = 0 unless defined $Useqq;
44 $Terse = 0 unless defined $Terse;
45 $Freezer = "" unless defined $Freezer;
46 $Toaster = "" unless defined $Toaster;
47 $Deepcopy = 0 unless defined $Deepcopy;
48 $Quotekeys = 1 unless defined $Quotekeys;
49 $Bless = "bless" unless defined $Bless;
50 #$Expdepth = 0 unless defined $Expdepth;
51 $Maxdepth = 0 unless defined $Maxdepth;
52 $Pair = ' => ' unless defined $Pair;
53 $Useperl = 0 unless defined $Useperl;
54 $Sortkeys = 0 unless defined $Sortkeys;
55 $Deparse = 0 unless defined $Deparse;
58 # expects an arrayref of values to be dumped.
59 # can optionally pass an arrayref of names for the values.
60 # names must have leading $ sign stripped. begin the name with *
61 # to cause output of arrays and hashes rather than refs.
66 croak "Usage: PACKAGE->new(ARRAYREF, [ARRAYREF])"
67 unless (defined($v) && (ref($v) eq 'ARRAY'));
68 $n = [] unless (defined($n) && (ref($n) eq 'ARRAY'));
71 level => 0, # current recursive depth
72 indent => $Indent, # various styles of indenting
73 pad => $Pad, # all lines prefixed by this string
74 xpad => "", # padding-per-level
75 apad => "", # added padding for hash keys n such
76 sep => "", # list separator
77 pair => $Pair, # hash key/value separator: defaults to ' => '
78 seen => {}, # local (nested) refs (id => [name, val])
79 todump => $v, # values to dump []
80 names => $n, # optional names for values []
81 varname => $Varname, # prefix to use for tagging nameless ones
82 purity => $Purity, # degree to which output is evalable
83 useqq => $Useqq, # use "" for strings (backslashitis ensues)
84 terse => $Terse, # avoid name output (where feasible)
85 freezer => $Freezer, # name of Freezer method for objects
86 toaster => $Toaster, # name of method to revive objects
87 deepcopy => $Deepcopy, # dont cross-ref, except to stop recursion
88 quotekeys => $Quotekeys, # quote hash keys
89 'bless' => $Bless, # keyword to use for "bless"
90 # expdepth => $Expdepth, # cutoff depth for explicit dumping
91 maxdepth => $Maxdepth, # depth beyond which we give up
92 useperl => $Useperl, # use the pure Perl implementation
93 sortkeys => $Sortkeys, # flag or filter for sorting hash keys
94 deparse => $Deparse, # use B::Deparse for coderefs
101 return bless($s, $c);
105 # Packed numeric addresses take less memory. Plus pack is faster than sprintf
106 *init_refaddr_format = sub {};
108 *format_refaddr = sub {
109 require Scalar::Util;
110 pack "J", Scalar::Util::refaddr(shift);
113 *init_refaddr_format = sub {
115 my $f = $Config::Config{uvxformat};
117 our $refaddr_format = "0x%" . $f;
120 *format_refaddr = sub {
121 require Scalar::Util;
122 sprintf our $refaddr_format, Scalar::Util::refaddr(shift);
127 # add-to or query the table of already seen references
131 if (defined($g) && (ref($g) eq 'HASH')) {
132 init_refaddr_format();
134 while (($k, $v) = each %$g) {
135 if (defined $v and ref $v) {
136 $id = format_refaddr($v);
137 if ($k =~ /^[*](.*)$/) {
138 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
139 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
140 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
143 elsif ($k !~ /^\$/) {
146 $s->{seen}{$id} = [$k, $v];
149 carp "Only refs supported, ignoring non-ref item \$$k";
155 return map { @$_ } values %{$s->{seen}};
160 # set or query the values to be dumped
164 if (defined($v) && (ref($v) eq 'ARRAY')) {
165 $s->{todump} = [@$v]; # make a copy
169 return @{$s->{todump}};
174 # set or query the names of the values to be dumped
178 if (defined($n) && (ref($n) eq 'ARRAY')) {
179 $s->{names} = [@$n]; # make a copy
183 return @{$s->{names}};
191 unless $Data::Dumper::Useperl || (ref($_[0]) && $_[0]->{useperl}) ||
192 $Data::Dumper::Useqq || (ref($_[0]) && $_[0]->{useqq}) ||
193 $Data::Dumper::Deparse || (ref($_[0]) && $_[0]->{deparse});
198 # dump the refs in the current dumper object.
199 # expects same args as new() if called via package name.
203 my(@out, $val, $name);
206 init_refaddr_format();
208 $s = $s->new(@_) unless ref $s;
210 for $val (@{$s->{todump}}) {
213 $name = $s->{names}[$i++];
215 if ($name =~ /^[*](.*)$/) {
217 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
218 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
219 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
226 elsif ($name !~ /^\$/) {
227 $name = "\$" . $name;
231 $name = "\$" . $s->{varname} . $i;
234 # Ensure hash iterator is reset
235 if (ref($val) eq 'HASH') {
241 local($s->{apad}) = $s->{apad};
242 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
243 $valstr = $s->_dump($val, $name);
246 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
247 $out .= $s->{pad} . $valstr . $s->{sep};
248 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
249 . ';' . $s->{sep} if @post;
253 return wantarray ? @out : join('', @out);
256 # wrap string in single quotes (escaping if needed)
259 $val =~ s/([\\\'])/\\$1/g;
260 return "'" . $val . "'";
264 # twist, toil and turn;
265 # and recurse, of course.
266 # sometimes sordidly;
267 # and curse if no recourse.
270 my($s, $val, $name) = @_;
272 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
279 # Call the freezer method if it's specified and the object has the
280 # method. Trap errors and warn() instead of die()ing, like the XS
282 my $freezer = $s->{freezer};
283 if ($freezer and UNIVERSAL::can($val, $freezer)) {
284 eval { $val->$freezer() };
285 warn "WARNING(Freezer method call failed): $@" if $@;
288 require Scalar::Util;
289 $realpack = Scalar::Util::blessed($val);
290 $realtype = $realpack ? Scalar::Util::reftype($val) : ref $val;
291 $id = format_refaddr($val);
293 # if it has a name, we need to either look it up, or keep a tab
294 # on it so we know when we hit it later
295 if (defined($name) and length($name)) {
296 # keep a tab on it so that we dont fall into recursive pit
297 if (exists $s->{seen}{$id}) {
298 # if ($s->{expdepth} < $s->{level}) {
299 if ($s->{purity} and $s->{level} > 0) {
300 $out = ($realtype eq 'HASH') ? '{}' :
301 ($realtype eq 'ARRAY') ? '[]' :
303 push @post, $name . " = " . $s->{seen}{$id}[0];
306 $out = $s->{seen}{$id}[0];
307 if ($name =~ /^([\@\%])/) {
309 if ($out =~ /^\\$start/) {
310 $out = substr($out, 1);
313 $out = $start . '{' . $out . '}';
322 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
323 ($realtype eq 'CODE' and
324 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
331 if ( $realpack and ($] >= 5.009005 ? re::is_regexp($val) : $realpack eq 'Regexp') ) {
333 $no_bless = $realpack eq 'Regexp';
336 # If purity is not set and maxdepth is set, then check depth:
337 # if we have reached maximum depth, return the string
338 # representation of the thing we are currently examining
339 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
341 and $s->{maxdepth} > 0
342 and $s->{level} >= $s->{maxdepth})
347 # we have a blessed ref
348 if ($realpack and !$no_bless) {
349 $out = $s->{'bless'} . '( ';
350 $blesspad = $s->{apad};
351 $s->{apad} .= ' ' if ($s->{indent} >= 2);
355 $ipad = $s->{xpad} x $s->{level};
359 # This really sucks, re:regexp_pattern is in ext/re/re.xs and not in
360 # universal.c, and even worse we cant just require that re to be loaded
361 # we *have* to use() it.
362 # We should probably move it to universal.c for 5.10.1 and fix this.
363 # Currently we only use re::regexp_pattern when the re is blessed into another
364 # package. This has the disadvantage of meaning that a DD dump won't round trip
365 # as the pattern will be repeatedly wrapped with the same modifiers.
366 # This is an aesthetic issue so we will leave it for now, but we could use
367 # regexp_pattern() in list context to get the modifiers separately.
368 # But since this means loading the full debugging engine in process we wont
369 # bother unless its necessary for accuracy.
370 if (($realpack ne 'Regexp') && defined(*re::regexp_pattern{CODE})) {
371 $pat = re::regexp_pattern($val);
378 elsif ($realtype eq 'SCALAR' || $realtype eq 'REF') {
380 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
383 $out .= '\\' . $s->_dump($$val, "\${$name}");
386 elsif ($realtype eq 'GLOB') {
387 $out .= '\\' . $s->_dump($$val, "*{$name}");
389 elsif ($realtype eq 'ARRAY') {
390 my($v, $pad, $mname);
392 $out .= ($name =~ /^\@/) ? '(' : '[';
393 $pad = $s->{sep} . $s->{pad} . $s->{apad};
394 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
395 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
396 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
397 ($mname = $name . '->');
398 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
400 $sname = $mname . '[' . $i . ']';
401 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
402 $out .= $pad . $ipad . $s->_dump($v, $sname);
403 $out .= "," if $i++ < $#$val;
405 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
406 $out .= ($name =~ /^\@/) ? ')' : ']';
408 elsif ($realtype eq 'HASH') {
409 my($k, $v, $pad, $lpad, $mname, $pair);
410 $out .= ($name =~ /^\%/) ? '(' : '{';
411 $pad = $s->{sep} . $s->{pad} . $s->{apad};
414 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
415 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
416 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
417 ($mname = $name . '->');
418 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
419 my ($sortkeys, $keys, $key) = ("$s->{sortkeys}");
421 if (ref($s->{sortkeys}) eq 'CODE') {
422 $keys = $s->{sortkeys}($val);
423 unless (ref($keys) eq 'ARRAY') {
424 carp "Sortkeys subroutine did not return ARRAYREF";
429 $keys = [ sort keys %$val ];
432 while (($k, $v) = ! $sortkeys ? (each %$val) :
433 @$keys ? ($key = shift(@$keys), $val->{$key}) :
436 my $nk = $s->_dump($k, "");
437 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
438 $sname = $mname . '{' . $nk . '}';
439 $out .= $pad . $ipad . $nk . $pair;
441 # temporarily alter apad
442 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
443 $out .= $s->_dump($val->{$k}, $sname) . ",";
444 $s->{apad} = $lpad if $s->{indent} >= 2;
446 if (substr($out, -1) eq ',') {
448 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
450 $out .= ($name =~ /^\%/) ? ')' : '}';
452 elsif ($realtype eq 'CODE') {
455 my $sub = 'sub ' . (B::Deparse->new)->coderef2text($val);
456 $pad = $s->{sep} . $s->{pad} . $s->{apad} . $s->{xpad} x ($s->{level} - 1);
457 $sub =~ s/\n/$pad/gse;
460 $out .= 'sub { "DUMMY" }';
461 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
465 croak "Can\'t handle $realtype type.";
468 if ($realpack and !$no_bless) { # we have a blessed ref
469 $out .= ', ' . _quote($realpack) . ' )';
470 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
471 $s->{apad} = $blesspad;
476 else { # simple scalar
479 # first, catalog the scalar
481 $id = format_refaddr($ref);
482 if (exists $s->{seen}{$id}) {
483 if ($s->{seen}{$id}[2]) {
484 $out = $s->{seen}{$id}[0];
490 #warn "[>\\$name]\n";
491 $s->{seen}{$id} = ["\\$name", $ref];
494 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
495 my $name = substr($val, 1);
496 if ($name =~ /^[A-Za-z_][\w:]*$/) {
497 $name =~ s/^main::/::/;
501 $sname = $s->_dump($name, "");
502 $sname = '{' . $sname . '}';
506 local ($s->{level}) = 0;
507 for $k (qw(SCALAR ARRAY HASH)) {
508 my $gval = *$val{$k};
509 next unless defined $gval;
510 next if $k eq "SCALAR" && ! defined $$gval; # always there
512 # _dump can push into @post, so we hold our place using $postlen
513 my $postlen = scalar @post;
514 $post[$postlen] = "\*$sname = ";
515 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
516 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
519 $out .= '*' . $sname;
521 elsif (!defined($val)) {
524 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})\z/) { # safe decimal number
528 if ($s->{useqq} or $val =~ tr/\0-\377//c) {
529 # Fall back to qq if there's Unicode
530 $out .= qquote($val, $s->{useqq});
533 $out .= _quote($val);
538 # if we made it this far, $id was added to seen list at current
539 # level, so remove it to get deep copies
540 if ($s->{deepcopy}) {
541 delete($s->{seen}{$id});
544 $s->{seen}{$id}[2] = 1;
551 # non-OO style of earlier version
554 return Data::Dumper->Dump([@_]);
559 return Data::Dumper->Dumpxs([@_], []);
562 sub Dumpf { return Data::Dumper->Dump(@_) }
564 sub Dumpp { print Data::Dumper->Dump(@_) }
567 # reset the "seen" cache
596 defined($v) ? (($s->{pair} = $v), return $s) : $s->{pair};
601 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
606 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
611 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
616 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
621 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
626 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
631 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
636 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
641 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
646 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
651 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
656 defined($v) ? (($s->{'useperl'} = $v), return $s) : $s->{'useperl'};
661 defined($v) ? (($s->{'sortkeys'} = $v), return $s) : $s->{'sortkeys'};
666 defined($v) ? (($s->{'deparse'} = $v), return $s) : $s->{'deparse'};
669 # used by qquote below
680 # put a string value in double quotes
683 s/([\\\"\@\$])/\\$1/g;
684 my $bytes; { use bytes; $bytes = length }
685 s/([^\x00-\x7f])/'\x{'.sprintf("%x",ord($1)).'}'/ge if $bytes > length;
686 return qq("$_") unless
687 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
689 my $high = shift || "";
690 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
692 if (ord('^')==94) { # ascii
693 # no need for 3 digits in escape for these
694 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
695 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
696 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
697 if ($high eq "iso8859") {
698 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
699 } elsif ($high eq "utf8") {
701 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
702 } elsif ($high eq "8bit") {
705 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
706 s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
710 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
711 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
712 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
713 {'\\'.sprintf('%03o',ord($1))}eg;
719 # helper sub to sort hash keys in Perl < 5.8.0 where we don't have
720 # access to sortsv() from XS
721 sub _sortkeys { [ sort keys %{$_[0]} ] }
728 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
734 # simple procedural interface
735 print Dumper($foo, $bar);
737 # extended usage with names
738 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
740 # configuration variables
742 local $Data::Dumper::Purity = 1;
743 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
747 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
751 $d->Purity(1)->Terse(1)->Deepcopy(1);
757 Given a list of scalars or reference variables, writes out their contents in
758 perl syntax. The references can also be objects. The contents of each
759 variable is output in a single Perl statement. Handles self-referential
760 structures correctly.
762 The return value can be C<eval>ed to get back an identical copy of the
763 original reference structure.
765 Any references that are the same as one of those passed in will be named
766 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
767 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
768 notation. You can specify names for individual values to be dumped if you
769 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
770 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
773 The default output of self-referential structures can be C<eval>ed, but the
774 nested references to C<$VAR>I<n> will be undefined, since a recursive
775 structure cannot be constructed using one Perl statement. You should set the
776 C<Purity> flag to 1 to get additional statements that will correctly fill in
777 these references. Moreover, if C<eval>ed when strictures are in effect,
778 you need to ensure that any variables it accesses are previously declared.
780 In the extended usage form, the references to be dumped can be given
781 user-specified names. If a name begins with a C<*>, the output will
782 describe the dereferenced type of the supplied reference for hashes and
783 arrays, and coderefs. Output of names will be avoided where possible if
784 the C<Terse> flag is set.
786 In many cases, methods that are used to set the internal state of the
787 object will return the object itself, so method calls can be conveniently
790 Several styles of output are possible, all controlled by setting
791 the C<Indent> flag. See L<Configuration Variables or Methods> below
799 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
801 Returns a newly created C<Data::Dumper> object. The first argument is an
802 anonymous array of values to be dumped. The optional second argument is an
803 anonymous array of names for the values. The names need not have a leading
804 C<$> sign, and must be comprised of alphanumeric characters. You can begin
805 a name with a C<*> to specify that the dereferenced type must be dumped
806 instead of the reference itself, for ARRAY and HASH references.
808 The prefix specified by C<$Data::Dumper::Varname> will be used with a
809 numeric suffix if the name for a value is undefined.
811 Data::Dumper will catalog all references encountered while dumping the
812 values. Cross-references (in the form of names of substructures in perl
813 syntax) will be inserted at all possible points, preserving any structural
814 interdependencies in the original set of values. Structure traversal is
815 depth-first, and proceeds in order from the first supplied value to
818 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
820 Returns the stringified form of the values stored in the object (preserving
821 the order in which they were supplied to C<new>), subject to the
822 configuration options below. In a list context, it returns a list
823 of strings corresponding to the supplied values.
825 The second form, for convenience, simply calls the C<new> method on its
826 arguments before dumping the object immediately.
828 =item I<$OBJ>->Seen(I<[HASHREF]>)
830 Queries or adds to the internal table of already encountered references.
831 You must use C<Reset> to explicitly clear the table if needed. Such
832 references are not dumped; instead, their names are inserted wherever they
833 are encountered subsequently. This is useful especially for properly
834 dumping subroutine references.
836 Expects an anonymous hash of name => value pairs. Same rules apply for names
837 as in C<new>. If no argument is supplied, will return the "seen" list of
838 name => value pairs, in a list context. Otherwise, returns the object
841 =item I<$OBJ>->Values(I<[ARRAYREF]>)
843 Queries or replaces the internal array of values that will be dumped.
844 When called without arguments, returns the values. Otherwise, returns the
847 =item I<$OBJ>->Names(I<[ARRAYREF]>)
849 Queries or replaces the internal array of user supplied names for the values
850 that will be dumped. When called without arguments, returns the names.
851 Otherwise, returns the object itself.
855 Clears the internal table of "seen" references and returns the object
864 =item Dumper(I<LIST>)
866 Returns the stringified form of the values in the list, subject to the
867 configuration options below. The values will be named C<$VAR>I<n> in the
868 output, where I<n> is a numeric suffix. Will return a list of strings
873 =head2 Configuration Variables or Methods
875 Several configuration variables can be used to control the kind of output
876 generated when using the procedural interface. These variables are usually
877 C<local>ized in a block so that other parts of the code are not affected by
880 These variables determine the default state of the object created by calling
881 the C<new> method, but cannot be used to alter the state of the object
882 thereafter. The equivalent method names should be used instead to query
883 or set the internal state of the object.
885 The method forms return the object itself when called with arguments,
886 so that they can be chained together nicely.
892 $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
894 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
895 spews output without any newlines, indentation, or spaces between list
896 items. It is the most compact format possible that can still be called
897 valid perl. Style 1 outputs a readable form with newlines but no fancy
898 indentation (each level in the structure is simply indented by a fixed
899 amount of whitespace). Style 2 (the default) outputs a very readable form
900 which takes into account the length of hash keys (so the hash value lines
901 up). Style 3 is like style 2, but also annotates the elements of arrays
902 with their index (but the comment is on its own line, so array output
903 consumes twice the number of lines). Style 2 is the default.
907 $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
909 Controls the degree to which the output can be C<eval>ed to recreate the
910 supplied reference structures. Setting it to 1 will output additional perl
911 statements that will correctly recreate nested references. The default is
916 $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
918 Specifies the string that will be prefixed to every line of the output.
919 Empty string by default.
923 $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
925 Contains the prefix to use for tagging variable names in the output. The
930 $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
932 When set, enables the use of double quotes for representing string values.
933 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
934 characters will be backslashed, and unprintable characters will be output as
935 quoted octal integers. Since setting this variable imposes a performance
936 penalty, the default is 0. C<Dump()> will run slower if this flag is set,
937 since the fast XSUB implementation doesn't support it yet.
941 $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
943 When set, Data::Dumper will emit single, non-self-referential values as
944 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
945 will be avoided where possible, but be advised that such output may not
946 always be parseable by C<eval>.
950 $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
952 Can be set to a method name, or to an empty string to disable the feature.
953 Data::Dumper will invoke that method via the object before attempting to
954 stringify it. This method can alter the contents of the object (if, for
955 instance, it contains data allocated from C), and even rebless it in a
956 different package. The client is responsible for making sure the specified
957 method can be called via the object, and that the object ends up containing
958 only perl data types after the method has been called. Defaults to an empty
961 If an object does not support the method specified (determined using
962 UNIVERSAL::can()) then the call will be skipped. If the method dies a
963 warning will be generated.
967 $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
969 Can be set to a method name, or to an empty string to disable the feature.
970 Data::Dumper will emit a method call for any objects that are to be dumped
971 using the syntax C<bless(DATA, CLASS)-E<gt>METHOD()>. Note that this means that
972 the method specified will have to perform any modifications required on the
973 object (like creating new state within it, and/or reblessing it in a
974 different package) and then return it. The client is responsible for making
975 sure the method can be called via the object, and that it returns a valid
976 object. Defaults to an empty string.
980 $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
982 Can be set to a boolean value to enable deep copies of structures.
983 Cross-referencing will then only be done when absolutely essential
984 (i.e., to break reference cycles). Default is 0.
988 $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
990 Can be set to a boolean value to control whether hash keys are quoted.
991 A false value will avoid quoting hash keys when it looks like a simple
992 string. Default is 1, which will always enclose hash keys in quotes.
996 $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
998 Can be set to a string that specifies an alternative to the C<bless>
999 builtin operator used to create objects. A function with the specified
1000 name should exist, and should accept the same arguments as the builtin.
1001 Default is C<bless>.
1005 $Data::Dumper::Pair I<or> $I<OBJ>->Pair(I<[NEWVAL]>)
1007 Can be set to a string that specifies the separator between hash keys
1008 and values. To dump nested hash, array and scalar values to JavaScript,
1009 use: C<$Data::Dumper::Pair = ' : ';>. Implementing C<bless> in JavaScript
1010 is left as an exercise for the reader.
1011 A function with the specified name exists, and accepts the same arguments
1014 Default is: C< =E<gt> >.
1018 $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
1020 Can be set to a positive integer that specifies the depth beyond which
1021 which we don't venture into a structure. Has no effect when
1022 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
1023 want to see more than enough). Default is 0, which means there is
1028 $Data::Dumper::Useperl I<or> $I<OBJ>->Useperl(I<[NEWVAL]>)
1030 Can be set to a boolean value which controls whether the pure Perl
1031 implementation of C<Data::Dumper> is used. The C<Data::Dumper> module is
1032 a dual implementation, with almost all functionality written in both
1033 pure Perl and also in XS ('C'). Since the XS version is much faster, it
1034 will always be used if possible. This option lets you override the
1035 default behavior, usually for testing purposes only. Default is 0, which
1036 means the XS implementation will be used if possible.
1040 $Data::Dumper::Sortkeys I<or> $I<OBJ>->Sortkeys(I<[NEWVAL]>)
1042 Can be set to a boolean value to control whether hash keys are dumped in
1043 sorted order. A true value will cause the keys of all hashes to be
1044 dumped in Perl's default sort order. Can also be set to a subroutine
1045 reference which will be called for each hash that is dumped. In this
1046 case C<Data::Dumper> will call the subroutine once for each hash,
1047 passing it the reference of the hash. The purpose of the subroutine is
1048 to return a reference to an array of the keys that will be dumped, in
1049 the order that they should be dumped. Using this feature, you can
1050 control both the order of the keys, and which keys are actually used. In
1051 other words, this subroutine acts as a filter by which you can exclude
1052 certain keys from being dumped. Default is 0, which means that hash keys
1057 $Data::Dumper::Deparse I<or> $I<OBJ>->Deparse(I<[NEWVAL]>)
1059 Can be set to a boolean value to control whether code references are
1060 turned into perl source code. If set to a true value, C<B::Deparse>
1061 will be used to get the source of the code reference. Using this option
1062 will force using the Perl implementation of the dumper, since the fast
1063 XSUB implementation doesn't support it.
1065 Caution : use this option only if you know that your coderefs will be
1066 properly reconstructed by C<B::Deparse>.
1080 Run these code snippets to get a quick feel for the behavior of this
1081 module. When you are through with these examples, you may want to
1082 add or change the various configuration variables described above,
1083 to see their behavior. (See the testsuite in the Data::Dumper
1084 distribution for more examples.)
1090 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
1092 package Fuz; # a weird REF-REF-SCALAR object
1093 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
1098 $boo = [ 1, [], "abcd", \*foo,
1099 {1 => 'a', 023 => 'b', 0x45 => 'c'},
1100 \\"p\q\'r", $foo, $fuz];
1106 $bar = eval(Dumper($boo));
1108 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
1110 $Data::Dumper::Terse = 1; # don't output names where feasible
1111 $Data::Dumper::Indent = 0; # turn off all pretty print
1112 print Dumper($boo), "\n";
1114 $Data::Dumper::Indent = 1; # mild pretty print
1117 $Data::Dumper::Indent = 3; # pretty print with array indices
1120 $Data::Dumper::Useqq = 1; # print strings in double quotes
1123 $Data::Dumper::Pair = " : "; # specify hash key/value separator
1128 # recursive structures
1138 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
1141 $Data::Dumper::Purity = 1; # fill in the holes for eval
1142 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
1143 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
1146 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
1147 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1150 $Data::Dumper::Purity = 0; # avoid cross-refs
1151 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1163 print Data::Dumper->Dump([$f], [qw(f)]);
1165 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
1166 print Data::Dumper->Dump([$f], [qw(f)]);
1170 # object-oriented usage
1173 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
1174 $d->Seen({'*c' => $c}); # stash a ref without printing it
1177 $d->Reset->Purity(0); # empty the seen cache
1178 print join "----\n", $d->Dump;
1186 sub new { bless { state => 'awake' }, shift }
1189 print STDERR "preparing to sleep\n";
1190 $s->{state} = 'asleep';
1191 return bless $s, 'Foo::ZZZ';
1197 print STDERR "waking up\n";
1198 $s->{state} = 'awake';
1199 return bless $s, 'Foo';
1205 $b = Data::Dumper->new([$a], ['c']);
1206 $b->Freezer('Freeze');
1207 $b->Toaster('Thaw');
1211 print Data::Dumper->Dump([$d], ['d']);
1215 # symbol substitution (useful for recreating CODE refs)
1218 sub foo { print "foo speaking\n" }
1221 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1222 $d->Seen({ '*foo' => \&foo });
1227 # sorting and filtering hash keys
1230 $Data::Dumper::Sortkeys = \&my_filter;
1231 my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' };
1232 my $bar = { %$foo };
1233 my $baz = { reverse %$foo };
1234 print Dumper [ $foo, $bar, $baz ];
1238 # return an array ref containing the hash keys to dump
1239 # in the order that you want them to be dumped
1241 # Sort the keys of %$foo in reverse numeric order
1242 $hash eq $foo ? (sort {$b <=> $a} keys %$hash) :
1243 # Only dump the odd number keys of %$bar
1244 $hash eq $bar ? (grep {$_ % 2} keys %$hash) :
1245 # Sort keys in default order for all other hashes
1252 Due to limitations of Perl subroutine call semantics, you cannot pass an
1253 array or hash. Prepend it with a C<\> to pass its reference instead. This
1254 will be remedied in time, now that Perl has subroutine prototypes.
1255 For now, you need to use the extended usage form, and prepend the
1256 name with a C<*> to output it as a hash or array.
1258 C<Data::Dumper> cheats with CODE references. If a code reference is
1259 encountered in the structure being processed (and if you haven't set
1260 the C<Deparse> flag), an anonymous subroutine that
1261 contains the string '"DUMMY"' will be inserted in its place, and a warning
1262 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1263 in mind that the anonymous sub that gets created is just a placeholder.
1264 Someday, perl will have a switch to cache-on-demand the string
1265 representation of a compiled piece of code, I hope. If you have prior
1266 knowledge of all the code refs that your data structures are likely
1267 to have, you can use the C<Seen> method to pre-seed the internal reference
1268 table and make the dumped output point to them, instead. See L</EXAMPLES>
1271 The C<Useqq> and C<Deparse> flags makes Dump() run slower, since the
1272 XSUB implementation does not support them.
1274 SCALAR objects have the weirdest looking C<bless> workaround.
1276 Pure Perl version of C<Data::Dumper> escapes UTF-8 strings correctly
1277 only in Perl 5.8.0 and later.
1281 Starting from Perl 5.8.1 different runs of Perl will have different
1282 ordering of hash keys. The change was done for greater security,
1283 see L<perlsec/"Algorithmic Complexity Attacks">. This means that
1284 different runs of Perl will have different Data::Dumper outputs if
1285 the data contains hashes. If you need to have identical Data::Dumper
1286 outputs from different runs of Perl, use the environment variable
1287 PERL_HASH_SEED, see L<perlrun/PERL_HASH_SEED>. Using this restores
1288 the old (platform-specific) ordering: an even prettier solution might
1289 be to use the C<Sortkeys> filter of Data::Dumper.
1293 Gurusamy Sarathy gsar@activestate.com
1295 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1296 This program is free software; you can redistribute it and/or
1297 modify it under the same terms as Perl itself.
1301 Version 2.121 (Aug 24 2003)