4 # convert perl data structures into perl syntax suitable for both printing
7 # Documentation at the __END__
12 $VERSION = '2.121_08';
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);
104 sub init_refaddr_format {
106 my $f = $Config::Config{uvxformat};
108 our $refaddr_format = "0x%" . $f;
112 require Scalar::Util;
113 sprintf our $refaddr_format, Scalar::Util::refaddr(shift);
117 # add-to or query the table of already seen references
121 if (defined($g) && (ref($g) eq 'HASH')) {
123 while (($k, $v) = each %$g) {
124 if (defined $v and ref $v) {
125 $id = format_refaddr($v);
126 if ($k =~ /^[*](.*)$/) {
127 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
128 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
129 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
132 elsif ($k !~ /^\$/) {
135 $s->{seen}{$id} = [$k, $v];
138 carp "Only refs supported, ignoring non-ref item \$$k";
144 return map { @$_ } values %{$s->{seen}};
149 # set or query the values to be dumped
153 if (defined($v) && (ref($v) eq 'ARRAY')) {
154 $s->{todump} = [@$v]; # make a copy
158 return @{$s->{todump}};
163 # set or query the names of the values to be dumped
167 if (defined($n) && (ref($n) eq 'ARRAY')) {
168 $s->{names} = [@$n]; # make a copy
172 return @{$s->{names}};
180 unless $Data::Dumper::Useperl || (ref($_[0]) && $_[0]->{useperl}) ||
181 $Data::Dumper::Useqq || (ref($_[0]) && $_[0]->{useqq}) ||
182 $Data::Dumper::Deparse || (ref($_[0]) && $_[0]->{deparse});
187 # dump the refs in the current dumper object.
188 # expects same args as new() if called via package name.
192 my(@out, $val, $name);
195 init_refaddr_format();
197 $s = $s->new(@_) unless ref $s;
199 for $val (@{$s->{todump}}) {
202 $name = $s->{names}[$i++];
204 if ($name =~ /^[*](.*)$/) {
206 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
207 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
208 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
215 elsif ($name !~ /^\$/) {
216 $name = "\$" . $name;
220 $name = "\$" . $s->{varname} . $i;
225 local($s->{apad}) = $s->{apad};
226 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
227 $valstr = $s->_dump($val, $name);
230 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
231 $out .= $s->{pad} . $valstr . $s->{sep};
232 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
233 . ';' . $s->{sep} if @post;
237 return wantarray ? @out : join('', @out);
241 # twist, toil and turn;
242 # and recurse, of course.
243 # sometimes sordidly;
244 # and curse if no recourse.
247 my($s, $val, $name) = @_;
249 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
256 # Call the freezer method if it's specified and the object has the
257 # method. Trap errors and warn() instead of die()ing, like the XS
259 my $freezer = $s->{freezer};
260 if ($freezer and UNIVERSAL::can($val, $freezer)) {
261 eval { $val->$freezer() };
262 warn "WARNING(Freezer method call failed): $@" if $@;
265 require Scalar::Util;
266 $realpack = Scalar::Util::blessed($val);
267 $realtype = $realpack ? Scalar::Util::reftype($val) : ref $val;
268 $id = format_refaddr($val);
270 # if it has a name, we need to either look it up, or keep a tab
271 # on it so we know when we hit it later
272 if (defined($name) and length($name)) {
273 # keep a tab on it so that we dont fall into recursive pit
274 if (exists $s->{seen}{$id}) {
275 # if ($s->{expdepth} < $s->{level}) {
276 if ($s->{purity} and $s->{level} > 0) {
277 $out = ($realtype eq 'HASH') ? '{}' :
278 ($realtype eq 'ARRAY') ? '[]' :
280 push @post, $name . " = " . $s->{seen}{$id}[0];
283 $out = $s->{seen}{$id}[0];
284 if ($name =~ /^([\@\%])/) {
286 if ($out =~ /^\\$start/) {
287 $out = substr($out, 1);
290 $out = $start . '{' . $out . '}';
299 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
300 ($realtype eq 'CODE' and
301 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
307 if ($realpack and $realpack eq 'Regexp') {
313 # If purity is not set and maxdepth is set, then check depth:
314 # if we have reached maximum depth, return the string
315 # representation of the thing we are currently examining
316 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
318 and $s->{maxdepth} > 0
319 and $s->{level} >= $s->{maxdepth})
324 # we have a blessed ref
326 $out = $s->{'bless'} . '( ';
327 $blesspad = $s->{apad};
328 $s->{apad} .= ' ' if ($s->{indent} >= 2);
332 $ipad = $s->{xpad} x $s->{level};
334 if ($realtype eq 'SCALAR' || $realtype eq 'REF') {
336 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
339 $out .= '\\' . $s->_dump($$val, "\${$name}");
342 elsif ($realtype eq 'GLOB') {
343 $out .= '\\' . $s->_dump($$val, "*{$name}");
345 elsif ($realtype eq 'ARRAY') {
346 my($v, $pad, $mname);
348 $out .= ($name =~ /^\@/) ? '(' : '[';
349 $pad = $s->{sep} . $s->{pad} . $s->{apad};
350 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
351 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
352 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
353 ($mname = $name . '->');
354 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
356 $sname = $mname . '[' . $i . ']';
357 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
358 $out .= $pad . $ipad . $s->_dump($v, $sname);
359 $out .= "," if $i++ < $#$val;
361 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
362 $out .= ($name =~ /^\@/) ? ')' : ']';
364 elsif ($realtype eq 'HASH') {
365 my($k, $v, $pad, $lpad, $mname, $pair);
366 $out .= ($name =~ /^\%/) ? '(' : '{';
367 $pad = $s->{sep} . $s->{pad} . $s->{apad};
370 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
371 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
372 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
373 ($mname = $name . '->');
374 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
375 my ($sortkeys, $keys, $key) = ("$s->{sortkeys}");
377 if (ref($s->{sortkeys}) eq 'CODE') {
378 $keys = $s->{sortkeys}($val);
379 unless (ref($keys) eq 'ARRAY') {
380 carp "Sortkeys subroutine did not return ARRAYREF";
385 $keys = [ sort keys %$val ];
388 while (($k, $v) = ! $sortkeys ? (each %$val) :
389 @$keys ? ($key = shift(@$keys), $val->{$key}) :
392 my $nk = $s->_dump($k, "");
393 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
394 $sname = $mname . '{' . $nk . '}';
395 $out .= $pad . $ipad . $nk . $pair;
397 # temporarily alter apad
398 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
399 $out .= $s->_dump($val->{$k}, $sname) . ",";
400 $s->{apad} = $lpad if $s->{indent} >= 2;
402 if (substr($out, -1) eq ',') {
404 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
406 $out .= ($name =~ /^\%/) ? ')' : '}';
408 elsif ($realtype eq 'CODE') {
411 my $sub = 'sub ' . (B::Deparse->new)->coderef2text($val);
412 $pad = $s->{sep} . $s->{pad} . $s->{apad} . $s->{xpad} x ($s->{level} - 1);
413 $sub =~ s/\n/$pad/gse;
416 $out .= 'sub { "DUMMY" }';
417 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
421 croak "Can\'t handle $realtype type.";
424 if ($realpack) { # we have a blessed ref
425 $out .= ', \'' . $realpack . '\'' . ' )';
426 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
427 $s->{apad} = $blesspad;
432 else { # simple scalar
435 # first, catalog the scalar
437 $id = format_refaddr($ref);
438 if (exists $s->{seen}{$id}) {
439 if ($s->{seen}{$id}[2]) {
440 $out = $s->{seen}{$id}[0];
446 #warn "[>\\$name]\n";
447 $s->{seen}{$id} = ["\\$name", $ref];
450 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
451 my $name = substr($val, 1);
452 if ($name =~ /^[A-Za-z_][\w:]*$/) {
453 $name =~ s/^main::/::/;
457 $sname = $s->_dump($name, "");
458 $sname = '{' . $sname . '}';
462 local ($s->{level}) = 0;
463 for $k (qw(SCALAR ARRAY HASH)) {
464 my $gval = *$val{$k};
465 next unless defined $gval;
466 next if $k eq "SCALAR" && ! defined $$gval; # always there
468 # _dump can push into @post, so we hold our place using $postlen
469 my $postlen = scalar @post;
470 $post[$postlen] = "\*$sname = ";
471 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
472 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
475 $out .= '*' . $sname;
477 elsif (!defined($val)) {
480 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})\z/) { # safe decimal number
484 if ($s->{useqq} or $val =~ tr/\0-\377//c) {
485 # Fall back to qq if there's unicode
486 $out .= qquote($val, $s->{useqq});
489 $val =~ s/([\\\'])/\\$1/g;
490 $out .= '\'' . $val . '\'';
495 # if we made it this far, $id was added to seen list at current
496 # level, so remove it to get deep copies
497 if ($s->{deepcopy}) {
498 delete($s->{seen}{$id});
501 $s->{seen}{$id}[2] = 1;
508 # non-OO style of earlier version
511 return Data::Dumper->Dump([@_]);
516 return Data::Dumper->Dumpxs([@_], []);
519 sub Dumpf { return Data::Dumper->Dump(@_) }
521 sub Dumpp { print Data::Dumper->Dump(@_) }
524 # reset the "seen" cache
553 defined($v) ? (($s->{pair} = $v), return $s) : $s->{pair};
558 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
563 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
568 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
573 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
578 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
583 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
588 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
593 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
598 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
603 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
608 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
613 defined($v) ? (($s->{'useperl'} = $v), return $s) : $s->{'useperl'};
618 defined($v) ? (($s->{'sortkeys'} = $v), return $s) : $s->{'sortkeys'};
623 defined($v) ? (($s->{'deparse'} = $v), return $s) : $s->{'deparse'};
626 # used by qquote below
637 # put a string value in double quotes
640 s/([\\\"\@\$])/\\$1/g;
641 my $bytes; { use bytes; $bytes = length }
642 s/([^\x00-\x7f])/'\x{'.sprintf("%x",ord($1)).'}'/ge if $bytes > length;
643 return qq("$_") unless
644 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
646 my $high = shift || "";
647 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
649 if (ord('^')==94) { # ascii
650 # no need for 3 digits in escape for these
651 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
652 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
653 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
654 if ($high eq "iso8859") {
655 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
656 } elsif ($high eq "utf8") {
658 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
659 } elsif ($high eq "8bit") {
662 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
663 s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
667 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
668 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
669 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
670 {'\\'.sprintf('%03o',ord($1))}eg;
676 # helper sub to sort hash keys in Perl < 5.8.0 where we don't have
677 # access to sortsv() from XS
678 sub _sortkeys { [ sort keys %{$_[0]} ] }
685 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
691 # simple procedural interface
692 print Dumper($foo, $bar);
694 # extended usage with names
695 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
697 # configuration variables
699 local $Data::Dumper::Purity = 1;
700 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
704 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
708 $d->Purity(1)->Terse(1)->Deepcopy(1);
714 Given a list of scalars or reference variables, writes out their contents in
715 perl syntax. The references can also be objects. The contents of each
716 variable is output in a single Perl statement. Handles self-referential
717 structures correctly.
719 The return value can be C<eval>ed to get back an identical copy of the
720 original reference structure.
722 Any references that are the same as one of those passed in will be named
723 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
724 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
725 notation. You can specify names for individual values to be dumped if you
726 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
727 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
730 The default output of self-referential structures can be C<eval>ed, but the
731 nested references to C<$VAR>I<n> will be undefined, since a recursive
732 structure cannot be constructed using one Perl statement. You should set the
733 C<Purity> flag to 1 to get additional statements that will correctly fill in
734 these references. Moreover, if C<eval>ed when strictures are in effect,
735 you need to ensure that any variables it accesses are previously declared.
737 In the extended usage form, the references to be dumped can be given
738 user-specified names. If a name begins with a C<*>, the output will
739 describe the dereferenced type of the supplied reference for hashes and
740 arrays, and coderefs. Output of names will be avoided where possible if
741 the C<Terse> flag is set.
743 In many cases, methods that are used to set the internal state of the
744 object will return the object itself, so method calls can be conveniently
747 Several styles of output are possible, all controlled by setting
748 the C<Indent> flag. See L<Configuration Variables or Methods> below
756 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
758 Returns a newly created C<Data::Dumper> object. The first argument is an
759 anonymous array of values to be dumped. The optional second argument is an
760 anonymous array of names for the values. The names need not have a leading
761 C<$> sign, and must be comprised of alphanumeric characters. You can begin
762 a name with a C<*> to specify that the dereferenced type must be dumped
763 instead of the reference itself, for ARRAY and HASH references.
765 The prefix specified by C<$Data::Dumper::Varname> will be used with a
766 numeric suffix if the name for a value is undefined.
768 Data::Dumper will catalog all references encountered while dumping the
769 values. Cross-references (in the form of names of substructures in perl
770 syntax) will be inserted at all possible points, preserving any structural
771 interdependencies in the original set of values. Structure traversal is
772 depth-first, and proceeds in order from the first supplied value to
775 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
777 Returns the stringified form of the values stored in the object (preserving
778 the order in which they were supplied to C<new>), subject to the
779 configuration options below. In a list context, it returns a list
780 of strings corresponding to the supplied values.
782 The second form, for convenience, simply calls the C<new> method on its
783 arguments before dumping the object immediately.
785 =item I<$OBJ>->Seen(I<[HASHREF]>)
787 Queries or adds to the internal table of already encountered references.
788 You must use C<Reset> to explicitly clear the table if needed. Such
789 references are not dumped; instead, their names are inserted wherever they
790 are encountered subsequently. This is useful especially for properly
791 dumping subroutine references.
793 Expects an anonymous hash of name => value pairs. Same rules apply for names
794 as in C<new>. If no argument is supplied, will return the "seen" list of
795 name => value pairs, in a list context. Otherwise, returns the object
798 =item I<$OBJ>->Values(I<[ARRAYREF]>)
800 Queries or replaces the internal array of values that will be dumped.
801 When called without arguments, returns the values. Otherwise, returns the
804 =item I<$OBJ>->Names(I<[ARRAYREF]>)
806 Queries or replaces the internal array of user supplied names for the values
807 that will be dumped. When called without arguments, returns the names.
808 Otherwise, returns the object itself.
812 Clears the internal table of "seen" references and returns the object
821 =item Dumper(I<LIST>)
823 Returns the stringified form of the values in the list, subject to the
824 configuration options below. The values will be named C<$VAR>I<n> in the
825 output, where I<n> is a numeric suffix. Will return a list of strings
830 =head2 Configuration Variables or Methods
832 Several configuration variables can be used to control the kind of output
833 generated when using the procedural interface. These variables are usually
834 C<local>ized in a block so that other parts of the code are not affected by
837 These variables determine the default state of the object created by calling
838 the C<new> method, but cannot be used to alter the state of the object
839 thereafter. The equivalent method names should be used instead to query
840 or set the internal state of the object.
842 The method forms return the object itself when called with arguments,
843 so that they can be chained together nicely.
849 $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
851 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
852 spews output without any newlines, indentation, or spaces between list
853 items. It is the most compact format possible that can still be called
854 valid perl. Style 1 outputs a readable form with newlines but no fancy
855 indentation (each level in the structure is simply indented by a fixed
856 amount of whitespace). Style 2 (the default) outputs a very readable form
857 which takes into account the length of hash keys (so the hash value lines
858 up). Style 3 is like style 2, but also annotates the elements of arrays
859 with their index (but the comment is on its own line, so array output
860 consumes twice the number of lines). Style 2 is the default.
864 $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
866 Controls the degree to which the output can be C<eval>ed to recreate the
867 supplied reference structures. Setting it to 1 will output additional perl
868 statements that will correctly recreate nested references. The default is
873 $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
875 Specifies the string that will be prefixed to every line of the output.
876 Empty string by default.
880 $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
882 Contains the prefix to use for tagging variable names in the output. The
887 $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
889 When set, enables the use of double quotes for representing string values.
890 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
891 characters will be backslashed, and unprintable characters will be output as
892 quoted octal integers. Since setting this variable imposes a performance
893 penalty, the default is 0. C<Dump()> will run slower if this flag is set,
894 since the fast XSUB implementation doesn't support it yet.
898 $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
900 When set, Data::Dumper will emit single, non-self-referential values as
901 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
902 will be avoided where possible, but be advised that such output may not
903 always be parseable by C<eval>.
907 $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
909 Can be set to a method name, or to an empty string to disable the feature.
910 Data::Dumper will invoke that method via the object before attempting to
911 stringify it. This method can alter the contents of the object (if, for
912 instance, it contains data allocated from C), and even rebless it in a
913 different package. The client is responsible for making sure the specified
914 method can be called via the object, and that the object ends up containing
915 only perl data types after the method has been called. Defaults to an empty
918 If an object does not support the method specified (determined using
919 UNIVERSAL::can()) then the call will be skipped. If the method dies a
920 warning will be generated.
924 $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
926 Can be set to a method name, or to an empty string to disable the feature.
927 Data::Dumper will emit a method call for any objects that are to be dumped
928 using the syntax C<bless(DATA, CLASS)-E<gt>METHOD()>. Note that this means that
929 the method specified will have to perform any modifications required on the
930 object (like creating new state within it, and/or reblessing it in a
931 different package) and then return it. The client is responsible for making
932 sure the method can be called via the object, and that it returns a valid
933 object. Defaults to an empty string.
937 $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
939 Can be set to a boolean value to enable deep copies of structures.
940 Cross-referencing will then only be done when absolutely essential
941 (i.e., to break reference cycles). Default is 0.
945 $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
947 Can be set to a boolean value to control whether hash keys are quoted.
948 A false value will avoid quoting hash keys when it looks like a simple
949 string. Default is 1, which will always enclose hash keys in quotes.
953 $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
955 Can be set to a string that specifies an alternative to the C<bless>
956 builtin operator used to create objects. A function with the specified
957 name should exist, and should accept the same arguments as the builtin.
962 $Data::Dumper::Pair I<or> $I<OBJ>->Pair(I<[NEWVAL]>)
964 Can be set to a string that specifies the separator between hash keys
965 and values. To dump nested hash, array and scalar values to JavaScript,
966 use: C<$Data::Dumper::Pair = ' : ';>. Implementing C<bless> in JavaScript
967 is left as an exercise for the reader.
968 A function with the specified name exists, and accepts the same arguments
971 Default is: C< =E<gt> >.
975 $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
977 Can be set to a positive integer that specifies the depth beyond which
978 which we don't venture into a structure. Has no effect when
979 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
980 want to see more than enough). Default is 0, which means there is
985 $Data::Dumper::Useperl I<or> $I<OBJ>->Useperl(I<[NEWVAL]>)
987 Can be set to a boolean value which controls whether the pure Perl
988 implementation of C<Data::Dumper> is used. The C<Data::Dumper> module is
989 a dual implementation, with almost all functionality written in both
990 pure Perl and also in XS ('C'). Since the XS version is much faster, it
991 will always be used if possible. This option lets you override the
992 default behavior, usually for testing purposes only. Default is 0, which
993 means the XS implementation will be used if possible.
997 $Data::Dumper::Sortkeys I<or> $I<OBJ>->Sortkeys(I<[NEWVAL]>)
999 Can be set to a boolean value to control whether hash keys are dumped in
1000 sorted order. A true value will cause the keys of all hashes to be
1001 dumped in Perl's default sort order. Can also be set to a subroutine
1002 reference which will be called for each hash that is dumped. In this
1003 case C<Data::Dumper> will call the subroutine once for each hash,
1004 passing it the reference of the hash. The purpose of the subroutine is
1005 to return a reference to an array of the keys that will be dumped, in
1006 the order that they should be dumped. Using this feature, you can
1007 control both the order of the keys, and which keys are actually used. In
1008 other words, this subroutine acts as a filter by which you can exclude
1009 certain keys from being dumped. Default is 0, which means that hash keys
1014 $Data::Dumper::Deparse I<or> $I<OBJ>->Deparse(I<[NEWVAL]>)
1016 Can be set to a boolean value to control whether code references are
1017 turned into perl source code. If set to a true value, C<B::Deparse>
1018 will be used to get the source of the code reference. Using this option
1019 will force using the Perl implementation of the dumper, since the fast
1020 XSUB implementation doesn't support it.
1022 Caution : use this option only if you know that your coderefs will be
1023 properly reconstructed by C<B::Deparse>.
1037 Run these code snippets to get a quick feel for the behavior of this
1038 module. When you are through with these examples, you may want to
1039 add or change the various configuration variables described above,
1040 to see their behavior. (See the testsuite in the Data::Dumper
1041 distribution for more examples.)
1047 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
1049 package Fuz; # a weird REF-REF-SCALAR object
1050 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
1055 $boo = [ 1, [], "abcd", \*foo,
1056 {1 => 'a', 023 => 'b', 0x45 => 'c'},
1057 \\"p\q\'r", $foo, $fuz];
1063 $bar = eval(Dumper($boo));
1065 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
1067 $Data::Dumper::Terse = 1; # don't output names where feasible
1068 $Data::Dumper::Indent = 0; # turn off all pretty print
1069 print Dumper($boo), "\n";
1071 $Data::Dumper::Indent = 1; # mild pretty print
1074 $Data::Dumper::Indent = 3; # pretty print with array indices
1077 $Data::Dumper::Useqq = 1; # print strings in double quotes
1080 $Data::Dumper::Pair = " : "; # specify hash key/value separator
1085 # recursive structures
1095 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
1098 $Data::Dumper::Purity = 1; # fill in the holes for eval
1099 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
1100 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
1103 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
1104 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1107 $Data::Dumper::Purity = 0; # avoid cross-refs
1108 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1120 print Data::Dumper->Dump([$f], [qw(f)]);
1122 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
1123 print Data::Dumper->Dump([$f], [qw(f)]);
1127 # object-oriented usage
1130 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
1131 $d->Seen({'*c' => $c}); # stash a ref without printing it
1134 $d->Reset->Purity(0); # empty the seen cache
1135 print join "----\n", $d->Dump;
1143 sub new { bless { state => 'awake' }, shift }
1146 print STDERR "preparing to sleep\n";
1147 $s->{state} = 'asleep';
1148 return bless $s, 'Foo::ZZZ';
1154 print STDERR "waking up\n";
1155 $s->{state} = 'awake';
1156 return bless $s, 'Foo';
1162 $b = Data::Dumper->new([$a], ['c']);
1163 $b->Freezer('Freeze');
1164 $b->Toaster('Thaw');
1168 print Data::Dumper->Dump([$d], ['d']);
1172 # symbol substitution (useful for recreating CODE refs)
1175 sub foo { print "foo speaking\n" }
1178 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1179 $d->Seen({ '*foo' => \&foo });
1184 # sorting and filtering hash keys
1187 $Data::Dumper::Sortkeys = \&my_filter;
1188 my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' };
1189 my $bar = { %$foo };
1190 my $baz = { reverse %$foo };
1191 print Dumper [ $foo, $bar, $baz ];
1195 # return an array ref containing the hash keys to dump
1196 # in the order that you want them to be dumped
1198 # Sort the keys of %$foo in reverse numeric order
1199 $hash eq $foo ? (sort {$b <=> $a} keys %$hash) :
1200 # Only dump the odd number keys of %$bar
1201 $hash eq $bar ? (grep {$_ % 2} keys %$hash) :
1202 # Sort keys in default order for all other hashes
1209 Due to limitations of Perl subroutine call semantics, you cannot pass an
1210 array or hash. Prepend it with a C<\> to pass its reference instead. This
1211 will be remedied in time, now that Perl has subroutine prototypes.
1212 For now, you need to use the extended usage form, and prepend the
1213 name with a C<*> to output it as a hash or array.
1215 C<Data::Dumper> cheats with CODE references. If a code reference is
1216 encountered in the structure being processed (and if you haven't set
1217 the C<Deparse> flag), an anonymous subroutine that
1218 contains the string '"DUMMY"' will be inserted in its place, and a warning
1219 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1220 in mind that the anonymous sub that gets created is just a placeholder.
1221 Someday, perl will have a switch to cache-on-demand the string
1222 representation of a compiled piece of code, I hope. If you have prior
1223 knowledge of all the code refs that your data structures are likely
1224 to have, you can use the C<Seen> method to pre-seed the internal reference
1225 table and make the dumped output point to them, instead. See L</EXAMPLES>
1228 The C<Useqq> and C<Deparse> flags makes Dump() run slower, since the
1229 XSUB implementation does not support them.
1231 SCALAR objects have the weirdest looking C<bless> workaround.
1233 Pure Perl version of C<Data::Dumper> escapes UTF-8 strings correctly
1234 only in Perl 5.8.0 and later.
1238 Starting from Perl 5.8.1 different runs of Perl will have different
1239 ordering of hash keys. The change was done for greater security,
1240 see L<perlsec/"Algorithmic Complexity Attacks">. This means that
1241 different runs of Perl will have different Data::Dumper outputs if
1242 the data contains hashes. If you need to have identical Data::Dumper
1243 outputs from different runs of Perl, use the environment variable
1244 PERL_HASH_SEED, see L<perlrun/PERL_HASH_SEED>. Using this restores
1245 the old (platform-specific) ordering: an even prettier solution might
1246 be to use the C<Sortkeys> filter of Data::Dumper.
1250 Gurusamy Sarathy gsar@activestate.com
1252 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1253 This program is free software; you can redistribute it and/or
1254 modify it under the same terms as Perl itself.
1258 Version 2.121 (Aug 24 2003)