4 # convert perl data structures into perl syntax suitable for both printing
7 # Documentation at the __END__
12 $VERSION = '2.121_13';
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($v) 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 . ';' . $s->{sep} if @post;
253 return wantarray ? @out : join('', @out);
257 # twist, toil and turn;
258 # and recurse, of course.
259 # sometimes sordidly;
260 # and curse if no recourse.
263 my($s, $val, $name) = @_;
265 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
272 # Call the freezer method if it's specified and the object has the
273 # method. Trap errors and warn() instead of die()ing, like the XS
275 my $freezer = $s->{freezer};
276 if ($freezer and UNIVERSAL::can($val, $freezer)) {
277 eval { $val->$freezer() };
278 warn "WARNING(Freezer method call failed): $@" if $@;
281 require Scalar::Util;
282 $realpack = Scalar::Util::blessed($val);
283 $realtype = $realpack ? Scalar::Util::reftype($val) : ref $val;
284 $id = format_refaddr($val);
286 # if it has a name, we need to either look it up, or keep a tab
287 # on it so we know when we hit it later
288 if (defined($name) and length($name)) {
289 # keep a tab on it so that we dont fall into recursive pit
290 if (exists $s->{seen}{$id}) {
291 # if ($s->{expdepth} < $s->{level}) {
292 if ($s->{purity} and $s->{level} > 0) {
293 $out = ($realtype eq 'HASH') ? '{}' :
294 ($realtype eq 'ARRAY') ? '[]' :
296 push @post, $name . " = " . $s->{seen}{$id}[0];
299 $out = $s->{seen}{$id}[0];
300 if ($name =~ /^([\@\%])/) {
302 if ($out =~ /^\\$start/) {
303 $out = substr($out, 1);
306 $out = $start . '{' . $out . '}';
315 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
316 ($realtype eq 'CODE' and
317 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
323 if ($realpack and $realpack eq 'Regexp') {
329 # If purity is not set and maxdepth is set, then check depth:
330 # if we have reached maximum depth, return the string
331 # representation of the thing we are currently examining
332 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
334 and $s->{maxdepth} > 0
335 and $s->{level} >= $s->{maxdepth})
340 # we have a blessed ref
342 $out = $s->{'bless'} . '( ';
343 $blesspad = $s->{apad};
344 $s->{apad} .= ' ' if ($s->{indent} >= 2);
348 $ipad = $s->{xpad} x $s->{level};
350 if ($realtype eq 'SCALAR' || $realtype eq 'REF') {
352 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
355 $out .= '\\' . $s->_dump($$val, "\${$name}");
358 elsif ($realtype eq 'GLOB') {
359 $out .= '\\' . $s->_dump($$val, "*{$name}");
361 elsif ($realtype eq 'ARRAY') {
362 my($v, $pad, $mname);
364 $out .= ($name =~ /^\@/) ? '(' : '[';
365 $pad = $s->{sep} . $s->{pad} . $s->{apad};
366 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
367 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
368 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
369 ($mname = $name . '->');
370 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
372 $sname = $mname . '[' . $i . ']';
373 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
374 $out .= $pad . $ipad . $s->_dump($v, $sname);
375 $out .= "," if $i++ < $#$val;
377 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
378 $out .= ($name =~ /^\@/) ? ')' : ']';
380 elsif ($realtype eq 'HASH') {
381 my($k, $v, $pad, $lpad, $mname, $pair);
382 $out .= ($name =~ /^\%/) ? '(' : '{';
383 $pad = $s->{sep} . $s->{pad} . $s->{apad};
386 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
387 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
388 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
389 ($mname = $name . '->');
390 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
391 my ($sortkeys, $keys, $key) = ("$s->{sortkeys}");
393 if (ref($s->{sortkeys}) eq 'CODE') {
394 $keys = $s->{sortkeys}($val);
395 unless (ref($keys) eq 'ARRAY') {
396 carp "Sortkeys subroutine did not return ARRAYREF";
401 $keys = [ sort keys %$val ];
404 while (($k, $v) = ! $sortkeys ? (each %$val) :
405 @$keys ? ($key = shift(@$keys), $val->{$key}) :
408 my $nk = $s->_dump($k, "");
409 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
410 $sname = $mname . '{' . $nk . '}';
411 $out .= $pad . $ipad . $nk . $pair;
413 # temporarily alter apad
414 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
415 $out .= $s->_dump($val->{$k}, $sname) . ",";
416 $s->{apad} = $lpad if $s->{indent} >= 2;
418 if (substr($out, -1) eq ',') {
420 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
422 $out .= ($name =~ /^\%/) ? ')' : '}';
424 elsif ($realtype eq 'CODE') {
427 my $sub = 'sub ' . (B::Deparse->new)->coderef2text($val);
428 $pad = $s->{sep} . $s->{pad} . $s->{apad} . $s->{xpad} x ($s->{level} - 1);
429 $sub =~ s/\n/$pad/gse;
432 $out .= 'sub { "DUMMY" }';
433 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
437 croak "Can\'t handle $realtype type.";
440 if ($realpack) { # we have a blessed ref
441 $out .= ', \'' . $realpack . '\'' . ' )';
442 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
443 $s->{apad} = $blesspad;
448 else { # simple scalar
451 # first, catalog the scalar
453 $id = format_refaddr($ref);
454 if (exists $s->{seen}{$id}) {
455 if ($s->{seen}{$id}[2]) {
456 $out = $s->{seen}{$id}[0];
462 #warn "[>\\$name]\n";
463 $s->{seen}{$id} = ["\\$name", $ref];
466 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
467 my $name = substr($val, 1);
468 if ($name =~ /^[A-Za-z_][\w:]*$/) {
469 $name =~ s/^main::/::/;
473 $sname = $s->_dump($name, "");
474 $sname = '{' . $sname . '}';
478 local ($s->{level}) = 0;
479 for $k (qw(SCALAR ARRAY HASH)) {
480 my $gval = *$val{$k};
481 next unless defined $gval;
482 next if $k eq "SCALAR" && ! defined $$gval; # always there
484 # _dump can push into @post, so we hold our place using $postlen
485 my $postlen = scalar @post;
486 $post[$postlen] = "\*$sname = ";
487 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
488 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
491 $out .= '*' . $sname;
493 elsif (!defined($val)) {
496 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})\z/) { # safe decimal number
500 if ($s->{useqq} or $val =~ tr/\0-\377//c) {
501 # Fall back to qq if there's Unicode
502 $out .= qquote($val, $s->{useqq});
505 $val =~ s/([\\\'])/\\$1/g;
506 $out .= '\'' . $val . '\'';
511 # if we made it this far, $id was added to seen list at current
512 # level, so remove it to get deep copies
513 if ($s->{deepcopy}) {
514 delete($s->{seen}{$id});
517 $s->{seen}{$id}[2] = 1;
524 # non-OO style of earlier version
527 return Data::Dumper->Dump([@_]);
532 return Data::Dumper->Dumpxs([@_], []);
535 sub Dumpf { return Data::Dumper->Dump(@_) }
537 sub Dumpp { print Data::Dumper->Dump(@_) }
540 # reset the "seen" cache
569 defined($v) ? (($s->{pair} = $v), return $s) : $s->{pair};
574 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
579 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
584 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
589 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
594 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
599 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
604 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
609 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
614 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
619 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
624 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
629 defined($v) ? (($s->{'useperl'} = $v), return $s) : $s->{'useperl'};
634 defined($v) ? (($s->{'sortkeys'} = $v), return $s) : $s->{'sortkeys'};
639 defined($v) ? (($s->{'deparse'} = $v), return $s) : $s->{'deparse'};
642 # used by qquote below
653 # put a string value in double quotes
656 s/([\\\"\@\$])/\\$1/g;
657 my $bytes; { use bytes; $bytes = length }
658 s/([^\x00-\x7f])/'\x{'.sprintf("%x",ord($1)).'}'/ge if $bytes > length;
659 return qq("$_") unless
660 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
662 my $high = shift || "";
663 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
665 if (ord('^')==94) { # ascii
666 # no need for 3 digits in escape for these
667 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
668 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
669 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
670 if ($high eq "iso8859") {
671 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
672 } elsif ($high eq "utf8") {
674 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
675 } elsif ($high eq "8bit") {
678 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
679 s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
683 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
684 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
685 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
686 {'\\'.sprintf('%03o',ord($1))}eg;
692 # helper sub to sort hash keys in Perl < 5.8.0 where we don't have
693 # access to sortsv() from XS
694 sub _sortkeys { [ sort keys %{$_[0]} ] }
701 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
707 # simple procedural interface
708 print Dumper($foo, $bar);
710 # extended usage with names
711 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
713 # configuration variables
715 local $Data::Dumper::Purity = 1;
716 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
720 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
724 $d->Purity(1)->Terse(1)->Deepcopy(1);
730 Given a list of scalars or reference variables, writes out their contents in
731 perl syntax. The references can also be objects. The contents of each
732 variable is output in a single Perl statement. Handles self-referential
733 structures correctly.
735 The return value can be C<eval>ed to get back an identical copy of the
736 original reference structure.
738 Any references that are the same as one of those passed in will be named
739 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
740 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
741 notation. You can specify names for individual values to be dumped if you
742 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
743 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
746 The default output of self-referential structures can be C<eval>ed, but the
747 nested references to C<$VAR>I<n> will be undefined, since a recursive
748 structure cannot be constructed using one Perl statement. You should set the
749 C<Purity> flag to 1 to get additional statements that will correctly fill in
750 these references. Moreover, if C<eval>ed when strictures are in effect,
751 you need to ensure that any variables it accesses are previously declared.
753 In the extended usage form, the references to be dumped can be given
754 user-specified names. If a name begins with a C<*>, the output will
755 describe the dereferenced type of the supplied reference for hashes and
756 arrays, and coderefs. Output of names will be avoided where possible if
757 the C<Terse> flag is set.
759 In many cases, methods that are used to set the internal state of the
760 object will return the object itself, so method calls can be conveniently
763 Several styles of output are possible, all controlled by setting
764 the C<Indent> flag. See L<Configuration Variables or Methods> below
772 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
774 Returns a newly created C<Data::Dumper> object. The first argument is an
775 anonymous array of values to be dumped. The optional second argument is an
776 anonymous array of names for the values. The names need not have a leading
777 C<$> sign, and must be comprised of alphanumeric characters. You can begin
778 a name with a C<*> to specify that the dereferenced type must be dumped
779 instead of the reference itself, for ARRAY and HASH references.
781 The prefix specified by C<$Data::Dumper::Varname> will be used with a
782 numeric suffix if the name for a value is undefined.
784 Data::Dumper will catalog all references encountered while dumping the
785 values. Cross-references (in the form of names of substructures in perl
786 syntax) will be inserted at all possible points, preserving any structural
787 interdependencies in the original set of values. Structure traversal is
788 depth-first, and proceeds in order from the first supplied value to
791 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
793 Returns the stringified form of the values stored in the object (preserving
794 the order in which they were supplied to C<new>), subject to the
795 configuration options below. In a list context, it returns a list
796 of strings corresponding to the supplied values.
798 The second form, for convenience, simply calls the C<new> method on its
799 arguments before dumping the object immediately.
801 =item I<$OBJ>->Seen(I<[HASHREF]>)
803 Queries or adds to the internal table of already encountered references.
804 You must use C<Reset> to explicitly clear the table if needed. Such
805 references are not dumped; instead, their names are inserted wherever they
806 are encountered subsequently. This is useful especially for properly
807 dumping subroutine references.
809 Expects an anonymous hash of name => value pairs. Same rules apply for names
810 as in C<new>. If no argument is supplied, will return the "seen" list of
811 name => value pairs, in a list context. Otherwise, returns the object
814 =item I<$OBJ>->Values(I<[ARRAYREF]>)
816 Queries or replaces the internal array of values that will be dumped.
817 When called without arguments, returns the values. Otherwise, returns the
820 =item I<$OBJ>->Names(I<[ARRAYREF]>)
822 Queries or replaces the internal array of user supplied names for the values
823 that will be dumped. When called without arguments, returns the names.
824 Otherwise, returns the object itself.
828 Clears the internal table of "seen" references and returns the object
837 =item Dumper(I<LIST>)
839 Returns the stringified form of the values in the list, subject to the
840 configuration options below. The values will be named C<$VAR>I<n> in the
841 output, where I<n> is a numeric suffix. Will return a list of strings
846 =head2 Configuration Variables or Methods
848 Several configuration variables can be used to control the kind of output
849 generated when using the procedural interface. These variables are usually
850 C<local>ized in a block so that other parts of the code are not affected by
853 These variables determine the default state of the object created by calling
854 the C<new> method, but cannot be used to alter the state of the object
855 thereafter. The equivalent method names should be used instead to query
856 or set the internal state of the object.
858 The method forms return the object itself when called with arguments,
859 so that they can be chained together nicely.
865 $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
867 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
868 spews output without any newlines, indentation, or spaces between list
869 items. It is the most compact format possible that can still be called
870 valid perl. Style 1 outputs a readable form with newlines but no fancy
871 indentation (each level in the structure is simply indented by a fixed
872 amount of whitespace). Style 2 (the default) outputs a very readable form
873 which takes into account the length of hash keys (so the hash value lines
874 up). Style 3 is like style 2, but also annotates the elements of arrays
875 with their index (but the comment is on its own line, so array output
876 consumes twice the number of lines). Style 2 is the default.
880 $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
882 Controls the degree to which the output can be C<eval>ed to recreate the
883 supplied reference structures. Setting it to 1 will output additional perl
884 statements that will correctly recreate nested references. The default is
889 $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
891 Specifies the string that will be prefixed to every line of the output.
892 Empty string by default.
896 $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
898 Contains the prefix to use for tagging variable names in the output. The
903 $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
905 When set, enables the use of double quotes for representing string values.
906 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
907 characters will be backslashed, and unprintable characters will be output as
908 quoted octal integers. Since setting this variable imposes a performance
909 penalty, the default is 0. C<Dump()> will run slower if this flag is set,
910 since the fast XSUB implementation doesn't support it yet.
914 $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
916 When set, Data::Dumper will emit single, non-self-referential values as
917 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
918 will be avoided where possible, but be advised that such output may not
919 always be parseable by C<eval>.
923 $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
925 Can be set to a method name, or to an empty string to disable the feature.
926 Data::Dumper will invoke that method via the object before attempting to
927 stringify it. This method can alter the contents of the object (if, for
928 instance, it contains data allocated from C), and even rebless it in a
929 different package. The client is responsible for making sure the specified
930 method can be called via the object, and that the object ends up containing
931 only perl data types after the method has been called. Defaults to an empty
934 If an object does not support the method specified (determined using
935 UNIVERSAL::can()) then the call will be skipped. If the method dies a
936 warning will be generated.
940 $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
942 Can be set to a method name, or to an empty string to disable the feature.
943 Data::Dumper will emit a method call for any objects that are to be dumped
944 using the syntax C<bless(DATA, CLASS)-E<gt>METHOD()>. Note that this means that
945 the method specified will have to perform any modifications required on the
946 object (like creating new state within it, and/or reblessing it in a
947 different package) and then return it. The client is responsible for making
948 sure the method can be called via the object, and that it returns a valid
949 object. Defaults to an empty string.
953 $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
955 Can be set to a boolean value to enable deep copies of structures.
956 Cross-referencing will then only be done when absolutely essential
957 (i.e., to break reference cycles). Default is 0.
961 $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
963 Can be set to a boolean value to control whether hash keys are quoted.
964 A false value will avoid quoting hash keys when it looks like a simple
965 string. Default is 1, which will always enclose hash keys in quotes.
969 $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
971 Can be set to a string that specifies an alternative to the C<bless>
972 builtin operator used to create objects. A function with the specified
973 name should exist, and should accept the same arguments as the builtin.
978 $Data::Dumper::Pair I<or> $I<OBJ>->Pair(I<[NEWVAL]>)
980 Can be set to a string that specifies the separator between hash keys
981 and values. To dump nested hash, array and scalar values to JavaScript,
982 use: C<$Data::Dumper::Pair = ' : ';>. Implementing C<bless> in JavaScript
983 is left as an exercise for the reader.
984 A function with the specified name exists, and accepts the same arguments
987 Default is: C< =E<gt> >.
991 $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
993 Can be set to a positive integer that specifies the depth beyond which
994 which we don't venture into a structure. Has no effect when
995 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
996 want to see more than enough). Default is 0, which means there is
1001 $Data::Dumper::Useperl I<or> $I<OBJ>->Useperl(I<[NEWVAL]>)
1003 Can be set to a boolean value which controls whether the pure Perl
1004 implementation of C<Data::Dumper> is used. The C<Data::Dumper> module is
1005 a dual implementation, with almost all functionality written in both
1006 pure Perl and also in XS ('C'). Since the XS version is much faster, it
1007 will always be used if possible. This option lets you override the
1008 default behavior, usually for testing purposes only. Default is 0, which
1009 means the XS implementation will be used if possible.
1013 $Data::Dumper::Sortkeys I<or> $I<OBJ>->Sortkeys(I<[NEWVAL]>)
1015 Can be set to a boolean value to control whether hash keys are dumped in
1016 sorted order. A true value will cause the keys of all hashes to be
1017 dumped in Perl's default sort order. Can also be set to a subroutine
1018 reference which will be called for each hash that is dumped. In this
1019 case C<Data::Dumper> will call the subroutine once for each hash,
1020 passing it the reference of the hash. The purpose of the subroutine is
1021 to return a reference to an array of the keys that will be dumped, in
1022 the order that they should be dumped. Using this feature, you can
1023 control both the order of the keys, and which keys are actually used. In
1024 other words, this subroutine acts as a filter by which you can exclude
1025 certain keys from being dumped. Default is 0, which means that hash keys
1030 $Data::Dumper::Deparse I<or> $I<OBJ>->Deparse(I<[NEWVAL]>)
1032 Can be set to a boolean value to control whether code references are
1033 turned into perl source code. If set to a true value, C<B::Deparse>
1034 will be used to get the source of the code reference. Using this option
1035 will force using the Perl implementation of the dumper, since the fast
1036 XSUB implementation doesn't support it.
1038 Caution : use this option only if you know that your coderefs will be
1039 properly reconstructed by C<B::Deparse>.
1053 Run these code snippets to get a quick feel for the behavior of this
1054 module. When you are through with these examples, you may want to
1055 add or change the various configuration variables described above,
1056 to see their behavior. (See the testsuite in the Data::Dumper
1057 distribution for more examples.)
1063 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
1065 package Fuz; # a weird REF-REF-SCALAR object
1066 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
1071 $boo = [ 1, [], "abcd", \*foo,
1072 {1 => 'a', 023 => 'b', 0x45 => 'c'},
1073 \\"p\q\'r", $foo, $fuz];
1079 $bar = eval(Dumper($boo));
1081 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
1083 $Data::Dumper::Terse = 1; # don't output names where feasible
1084 $Data::Dumper::Indent = 0; # turn off all pretty print
1085 print Dumper($boo), "\n";
1087 $Data::Dumper::Indent = 1; # mild pretty print
1090 $Data::Dumper::Indent = 3; # pretty print with array indices
1093 $Data::Dumper::Useqq = 1; # print strings in double quotes
1096 $Data::Dumper::Pair = " : "; # specify hash key/value separator
1101 # recursive structures
1111 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
1114 $Data::Dumper::Purity = 1; # fill in the holes for eval
1115 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
1116 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
1119 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
1120 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1123 $Data::Dumper::Purity = 0; # avoid cross-refs
1124 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1136 print Data::Dumper->Dump([$f], [qw(f)]);
1138 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
1139 print Data::Dumper->Dump([$f], [qw(f)]);
1143 # object-oriented usage
1146 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
1147 $d->Seen({'*c' => $c}); # stash a ref without printing it
1150 $d->Reset->Purity(0); # empty the seen cache
1151 print join "----\n", $d->Dump;
1159 sub new { bless { state => 'awake' }, shift }
1162 print STDERR "preparing to sleep\n";
1163 $s->{state} = 'asleep';
1164 return bless $s, 'Foo::ZZZ';
1170 print STDERR "waking up\n";
1171 $s->{state} = 'awake';
1172 return bless $s, 'Foo';
1178 $b = Data::Dumper->new([$a], ['c']);
1179 $b->Freezer('Freeze');
1180 $b->Toaster('Thaw');
1184 print Data::Dumper->Dump([$d], ['d']);
1188 # symbol substitution (useful for recreating CODE refs)
1191 sub foo { print "foo speaking\n" }
1194 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1195 $d->Seen({ '*foo' => \&foo });
1200 # sorting and filtering hash keys
1203 $Data::Dumper::Sortkeys = \&my_filter;
1204 my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' };
1205 my $bar = { %$foo };
1206 my $baz = { reverse %$foo };
1207 print Dumper [ $foo, $bar, $baz ];
1211 # return an array ref containing the hash keys to dump
1212 # in the order that you want them to be dumped
1214 # Sort the keys of %$foo in reverse numeric order
1215 $hash eq $foo ? (sort {$b <=> $a} keys %$hash) :
1216 # Only dump the odd number keys of %$bar
1217 $hash eq $bar ? (grep {$_ % 2} keys %$hash) :
1218 # Sort keys in default order for all other hashes
1225 Due to limitations of Perl subroutine call semantics, you cannot pass an
1226 array or hash. Prepend it with a C<\> to pass its reference instead. This
1227 will be remedied in time, now that Perl has subroutine prototypes.
1228 For now, you need to use the extended usage form, and prepend the
1229 name with a C<*> to output it as a hash or array.
1231 C<Data::Dumper> cheats with CODE references. If a code reference is
1232 encountered in the structure being processed (and if you haven't set
1233 the C<Deparse> flag), an anonymous subroutine that
1234 contains the string '"DUMMY"' will be inserted in its place, and a warning
1235 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1236 in mind that the anonymous sub that gets created is just a placeholder.
1237 Someday, perl will have a switch to cache-on-demand the string
1238 representation of a compiled piece of code, I hope. If you have prior
1239 knowledge of all the code refs that your data structures are likely
1240 to have, you can use the C<Seen> method to pre-seed the internal reference
1241 table and make the dumped output point to them, instead. See L</EXAMPLES>
1244 The C<Useqq> and C<Deparse> flags makes Dump() run slower, since the
1245 XSUB implementation does not support them.
1247 SCALAR objects have the weirdest looking C<bless> workaround.
1249 Pure Perl version of C<Data::Dumper> escapes UTF-8 strings correctly
1250 only in Perl 5.8.0 and later.
1254 Starting from Perl 5.8.1 different runs of Perl will have different
1255 ordering of hash keys. The change was done for greater security,
1256 see L<perlsec/"Algorithmic Complexity Attacks">. This means that
1257 different runs of Perl will have different Data::Dumper outputs if
1258 the data contains hashes. If you need to have identical Data::Dumper
1259 outputs from different runs of Perl, use the environment variable
1260 PERL_HASH_SEED, see L<perlrun/PERL_HASH_SEED>. Using this restores
1261 the old (platform-specific) ordering: an even prettier solution might
1262 be to use the C<Sortkeys> filter of Data::Dumper.
1266 Gurusamy Sarathy gsar@activestate.com
1268 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1269 This program is free software; you can redistribute it and/or
1270 modify it under the same terms as Perl itself.
1274 Version 2.121 (Aug 24 2003)