4 # convert perl data structures into perl syntax suitable for both printing
7 # Documentation at the __END__
12 $VERSION = '2.121_04';
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, $c);
105 # add-to or query the table of already seen references
109 if (defined($g) && (ref($g) eq 'HASH')) {
111 while (($k, $v) = each %$g) {
112 if (defined $v and ref $v) {
113 ($id) = (overload::StrVal($v) =~ /\((.*)\)$/);
114 if ($k =~ /^[*](.*)$/) {
115 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
116 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
117 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
120 elsif ($k !~ /^\$/) {
123 $s->{seen}{$id} = [$k, $v];
126 carp "Only refs supported, ignoring non-ref item \$$k";
132 return map { @$_ } values %{$s->{seen}};
137 # set or query the values to be dumped
141 if (defined($v) && (ref($v) eq 'ARRAY')) {
142 $s->{todump} = [@$v]; # make a copy
146 return @{$s->{todump}};
151 # set or query the names of the values to be dumped
155 if (defined($n) && (ref($n) eq 'ARRAY')) {
156 $s->{names} = [@$n]; # make a copy
160 return @{$s->{names}};
168 unless $Data::Dumper::Useperl || (ref($_[0]) && $_[0]->{useperl}) ||
169 $Data::Dumper::Useqq || (ref($_[0]) && $_[0]->{useqq}) ||
170 $Data::Dumper::Deparse || (ref($_[0]) && $_[0]->{deparse});
175 # dump the refs in the current dumper object.
176 # expects same args as new() if called via package name.
180 my(@out, $val, $name);
184 $s = $s->new(@_) unless ref $s;
186 for $val (@{$s->{todump}}) {
189 $name = $s->{names}[$i++];
191 if ($name =~ /^[*](.*)$/) {
193 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
194 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
195 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
202 elsif ($name !~ /^\$/) {
203 $name = "\$" . $name;
207 $name = "\$" . $s->{varname} . $i;
212 local($s->{apad}) = $s->{apad};
213 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
214 $valstr = $s->_dump($val, $name);
217 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
218 $out .= $s->{pad} . $valstr . $s->{sep};
219 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
220 . ';' . $s->{sep} if @post;
224 return wantarray ? @out : join('', @out);
228 # twist, toil and turn;
229 # and recurse, of course.
230 # sometimes sordidly;
231 # and curse if no recourse.
234 my($s, $val, $name) = @_;
236 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
243 # Call the freezer method if it's specified and the object has the
244 # method. Trap errors and warn() instead of die()ing, like the XS
246 my $freezer = $s->{freezer};
247 if ($freezer and UNIVERSAL::can($val, $freezer)) {
248 eval { $val->$freezer() };
249 warn "WARNING(Freezer method call failed): $@" if $@;
252 ($realpack, $realtype, $id) =
253 (overload::StrVal($val) =~ /^(?:(.*)\=)?([^=]*)\(([^\(]*)\)$/);
255 # if it has a name, we need to either look it up, or keep a tab
256 # on it so we know when we hit it later
257 if (defined($name) and length($name)) {
258 # keep a tab on it so that we dont fall into recursive pit
259 if (exists $s->{seen}{$id}) {
260 # if ($s->{expdepth} < $s->{level}) {
261 if ($s->{purity} and $s->{level} > 0) {
262 $out = ($realtype eq 'HASH') ? '{}' :
263 ($realtype eq 'ARRAY') ? '[]' :
265 push @post, $name . " = " . $s->{seen}{$id}[0];
268 $out = $s->{seen}{$id}[0];
269 if ($name =~ /^([\@\%])/) {
271 if ($out =~ /^\\$start/) {
272 $out = substr($out, 1);
275 $out = $start . '{' . $out . '}';
284 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
285 ($realtype eq 'CODE' and
286 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
292 if ($realpack and $realpack eq 'Regexp') {
298 # If purity is not set and maxdepth is set, then check depth:
299 # if we have reached maximum depth, return the string
300 # representation of the thing we are currently examining
301 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
303 and $s->{maxdepth} > 0
304 and $s->{level} >= $s->{maxdepth})
309 # we have a blessed ref
311 $out = $s->{'bless'} . '( ';
312 $blesspad = $s->{apad};
313 $s->{apad} .= ' ' if ($s->{indent} >= 2);
317 $ipad = $s->{xpad} x $s->{level};
319 if ($realtype eq 'SCALAR' || $realtype eq 'REF') {
321 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
324 $out .= '\\' . $s->_dump($$val, "\${$name}");
327 elsif ($realtype eq 'GLOB') {
328 $out .= '\\' . $s->_dump($$val, "*{$name}");
330 elsif ($realtype eq 'ARRAY') {
331 my($v, $pad, $mname);
333 $out .= ($name =~ /^\@/) ? '(' : '[';
334 $pad = $s->{sep} . $s->{pad} . $s->{apad};
335 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
336 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
337 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
338 ($mname = $name . '->');
339 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
341 $sname = $mname . '[' . $i . ']';
342 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
343 $out .= $pad . $ipad . $s->_dump($v, $sname);
344 $out .= "," if $i++ < $#$val;
346 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
347 $out .= ($name =~ /^\@/) ? ')' : ']';
349 elsif ($realtype eq 'HASH') {
350 my($k, $v, $pad, $lpad, $mname, $pair);
351 $out .= ($name =~ /^\%/) ? '(' : '{';
352 $pad = $s->{sep} . $s->{pad} . $s->{apad};
355 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
356 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
357 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
358 ($mname = $name . '->');
359 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
360 my ($sortkeys, $keys, $key) = ("$s->{sortkeys}");
362 if (ref($s->{sortkeys}) eq 'CODE') {
363 $keys = $s->{sortkeys}($val);
364 unless (ref($keys) eq 'ARRAY') {
365 carp "Sortkeys subroutine did not return ARRAYREF";
370 $keys = [ sort keys %$val ];
373 while (($k, $v) = ! $sortkeys ? (each %$val) :
374 @$keys ? ($key = shift(@$keys), $val->{$key}) :
377 my $nk = $s->_dump($k, "");
378 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
379 $sname = $mname . '{' . $nk . '}';
380 $out .= $pad . $ipad . $nk . $pair;
382 # temporarily alter apad
383 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
384 $out .= $s->_dump($val->{$k}, $sname) . ",";
385 $s->{apad} = $lpad if $s->{indent} >= 2;
387 if (substr($out, -1) eq ',') {
389 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
391 $out .= ($name =~ /^\%/) ? ')' : '}';
393 elsif ($realtype eq 'CODE') {
396 my $sub = 'sub ' . (B::Deparse->new)->coderef2text($val);
397 $pad = $s->{sep} . $s->{pad} . $s->{apad} . $s->{xpad} x ($s->{level} - 1);
398 $sub =~ s/\n/$pad/gse;
401 $out .= 'sub { "DUMMY" }';
402 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
406 croak "Can\'t handle $realtype type.";
409 if ($realpack) { # we have a blessed ref
410 $out .= ', \'' . $realpack . '\'' . ' )';
411 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
412 $s->{apad} = $blesspad;
417 else { # simple scalar
420 # first, catalog the scalar
422 ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
423 if (exists $s->{seen}{$id}) {
424 if ($s->{seen}{$id}[2]) {
425 $out = $s->{seen}{$id}[0];
431 #warn "[>\\$name]\n";
432 $s->{seen}{$id} = ["\\$name", $ref];
435 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
436 my $name = substr($val, 1);
437 if ($name =~ /^[A-Za-z_][\w:]*$/) {
438 $name =~ s/^main::/::/;
442 $sname = $s->_dump($name, "");
443 $sname = '{' . $sname . '}';
447 local ($s->{level}) = 0;
448 for $k (qw(SCALAR ARRAY HASH)) {
449 my $gval = *$val{$k};
450 next unless defined $gval;
451 next if $k eq "SCALAR" && ! defined $$gval; # always there
453 # _dump can push into @post, so we hold our place using $postlen
454 my $postlen = scalar @post;
455 $post[$postlen] = "\*$sname = ";
456 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
457 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
460 $out .= '*' . $sname;
462 elsif (!defined($val)) {
465 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})\z/) { # safe decimal number
469 if ($s->{useqq} or $val =~ tr/\0-\377//c) {
470 # Fall back to qq if there's unicode
471 $out .= qquote($val, $s->{useqq});
474 $val =~ s/([\\\'])/\\$1/g;
475 $out .= '\'' . $val . '\'';
480 # if we made it this far, $id was added to seen list at current
481 # level, so remove it to get deep copies
482 if ($s->{deepcopy}) {
483 delete($s->{seen}{$id});
486 $s->{seen}{$id}[2] = 1;
493 # non-OO style of earlier version
496 return Data::Dumper->Dump([@_]);
501 return Data::Dumper->Dumpxs([@_], []);
504 sub Dumpf { return Data::Dumper->Dump(@_) }
506 sub Dumpp { print Data::Dumper->Dump(@_) }
509 # reset the "seen" cache
538 defined($v) ? (($s->{pair} = $v), return $s) : $s->{pair};
543 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
548 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
553 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
558 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
563 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
568 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
573 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
578 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
583 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
588 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
593 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
598 defined($v) ? (($s->{'useperl'} = $v), return $s) : $s->{'useperl'};
603 defined($v) ? (($s->{'sortkeys'} = $v), return $s) : $s->{'sortkeys'};
608 defined($v) ? (($s->{'deparse'} = $v), return $s) : $s->{'deparse'};
611 # used by qquote below
622 # put a string value in double quotes
625 s/([\\\"\@\$])/\\$1/g;
626 my $bytes; { use bytes; $bytes = length }
627 s/([^\x00-\x7f])/'\x{'.sprintf("%x",ord($1)).'}'/ge if $bytes > length;
628 return qq("$_") unless
629 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
631 my $high = shift || "";
632 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
634 if (ord('^')==94) { # ascii
635 # no need for 3 digits in escape for these
636 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
637 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
638 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
639 if ($high eq "iso8859") {
640 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
641 } elsif ($high eq "utf8") {
643 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
644 } elsif ($high eq "8bit") {
647 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
648 s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
652 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
653 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
654 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
655 {'\\'.sprintf('%03o',ord($1))}eg;
661 # helper sub to sort hash keys in Perl < 5.8.0 where we don't have
662 # access to sortsv() from XS
663 sub _sortkeys { [ sort keys %{$_[0]} ] }
670 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
676 # simple procedural interface
677 print Dumper($foo, $bar);
679 # extended usage with names
680 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
682 # configuration variables
684 local $Data::Dumper::Purity = 1;
685 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
689 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
693 $d->Purity(1)->Terse(1)->Deepcopy(1);
699 Given a list of scalars or reference variables, writes out their contents in
700 perl syntax. The references can also be objects. The contents of each
701 variable is output in a single Perl statement. Handles self-referential
702 structures correctly.
704 The return value can be C<eval>ed to get back an identical copy of the
705 original reference structure.
707 Any references that are the same as one of those passed in will be named
708 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
709 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
710 notation. You can specify names for individual values to be dumped if you
711 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
712 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
715 The default output of self-referential structures can be C<eval>ed, but the
716 nested references to C<$VAR>I<n> will be undefined, since a recursive
717 structure cannot be constructed using one Perl statement. You should set the
718 C<Purity> flag to 1 to get additional statements that will correctly fill in
719 these references. Moreover, if C<eval>ed when strictures are in effect,
720 you need to ensure that any variables it accesses are previously declared.
722 In the extended usage form, the references to be dumped can be given
723 user-specified names. If a name begins with a C<*>, the output will
724 describe the dereferenced type of the supplied reference for hashes and
725 arrays, and coderefs. Output of names will be avoided where possible if
726 the C<Terse> flag is set.
728 In many cases, methods that are used to set the internal state of the
729 object will return the object itself, so method calls can be conveniently
732 Several styles of output are possible, all controlled by setting
733 the C<Indent> flag. See L<Configuration Variables or Methods> below
741 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
743 Returns a newly created C<Data::Dumper> object. The first argument is an
744 anonymous array of values to be dumped. The optional second argument is an
745 anonymous array of names for the values. The names need not have a leading
746 C<$> sign, and must be comprised of alphanumeric characters. You can begin
747 a name with a C<*> to specify that the dereferenced type must be dumped
748 instead of the reference itself, for ARRAY and HASH references.
750 The prefix specified by C<$Data::Dumper::Varname> will be used with a
751 numeric suffix if the name for a value is undefined.
753 Data::Dumper will catalog all references encountered while dumping the
754 values. Cross-references (in the form of names of substructures in perl
755 syntax) will be inserted at all possible points, preserving any structural
756 interdependencies in the original set of values. Structure traversal is
757 depth-first, and proceeds in order from the first supplied value to
760 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
762 Returns the stringified form of the values stored in the object (preserving
763 the order in which they were supplied to C<new>), subject to the
764 configuration options below. In a list context, it returns a list
765 of strings corresponding to the supplied values.
767 The second form, for convenience, simply calls the C<new> method on its
768 arguments before dumping the object immediately.
770 =item I<$OBJ>->Seen(I<[HASHREF]>)
772 Queries or adds to the internal table of already encountered references.
773 You must use C<Reset> to explicitly clear the table if needed. Such
774 references are not dumped; instead, their names are inserted wherever they
775 are encountered subsequently. This is useful especially for properly
776 dumping subroutine references.
778 Expects an anonymous hash of name => value pairs. Same rules apply for names
779 as in C<new>. If no argument is supplied, will return the "seen" list of
780 name => value pairs, in a list context. Otherwise, returns the object
783 =item I<$OBJ>->Values(I<[ARRAYREF]>)
785 Queries or replaces the internal array of values that will be dumped.
786 When called without arguments, returns the values. Otherwise, returns the
789 =item I<$OBJ>->Names(I<[ARRAYREF]>)
791 Queries or replaces the internal array of user supplied names for the values
792 that will be dumped. When called without arguments, returns the names.
793 Otherwise, returns the object itself.
797 Clears the internal table of "seen" references and returns the object
806 =item Dumper(I<LIST>)
808 Returns the stringified form of the values in the list, subject to the
809 configuration options below. The values will be named C<$VAR>I<n> in the
810 output, where I<n> is a numeric suffix. Will return a list of strings
815 =head2 Configuration Variables or Methods
817 Several configuration variables can be used to control the kind of output
818 generated when using the procedural interface. These variables are usually
819 C<local>ized in a block so that other parts of the code are not affected by
822 These variables determine the default state of the object created by calling
823 the C<new> method, but cannot be used to alter the state of the object
824 thereafter. The equivalent method names should be used instead to query
825 or set the internal state of the object.
827 The method forms return the object itself when called with arguments,
828 so that they can be chained together nicely.
834 $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
836 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
837 spews output without any newlines, indentation, or spaces between list
838 items. It is the most compact format possible that can still be called
839 valid perl. Style 1 outputs a readable form with newlines but no fancy
840 indentation (each level in the structure is simply indented by a fixed
841 amount of whitespace). Style 2 (the default) outputs a very readable form
842 which takes into account the length of hash keys (so the hash value lines
843 up). Style 3 is like style 2, but also annotates the elements of arrays
844 with their index (but the comment is on its own line, so array output
845 consumes twice the number of lines). Style 2 is the default.
849 $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
851 Controls the degree to which the output can be C<eval>ed to recreate the
852 supplied reference structures. Setting it to 1 will output additional perl
853 statements that will correctly recreate nested references. The default is
858 $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
860 Specifies the string that will be prefixed to every line of the output.
861 Empty string by default.
865 $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
867 Contains the prefix to use for tagging variable names in the output. The
872 $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
874 When set, enables the use of double quotes for representing string values.
875 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
876 characters will be backslashed, and unprintable characters will be output as
877 quoted octal integers. Since setting this variable imposes a performance
878 penalty, the default is 0. C<Dump()> will run slower if this flag is set,
879 since the fast XSUB implementation doesn't support it yet.
883 $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
885 When set, Data::Dumper will emit single, non-self-referential values as
886 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
887 will be avoided where possible, but be advised that such output may not
888 always be parseable by C<eval>.
892 $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
894 Can be set to a method name, or to an empty string to disable the feature.
895 Data::Dumper will invoke that method via the object before attempting to
896 stringify it. This method can alter the contents of the object (if, for
897 instance, it contains data allocated from C), and even rebless it in a
898 different package. The client is responsible for making sure the specified
899 method can be called via the object, and that the object ends up containing
900 only perl data types after the method has been called. Defaults to an empty
903 If an object does not support the method specified (determined using
904 UNIVERSAL::can()) then the call will be skipped. If the method dies a
905 warning will be generated.
909 $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
911 Can be set to a method name, or to an empty string to disable the feature.
912 Data::Dumper will emit a method call for any objects that are to be dumped
913 using the syntax C<bless(DATA, CLASS)-E<gt>METHOD()>. Note that this means that
914 the method specified will have to perform any modifications required on the
915 object (like creating new state within it, and/or reblessing it in a
916 different package) and then return it. The client is responsible for making
917 sure the method can be called via the object, and that it returns a valid
918 object. Defaults to an empty string.
922 $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
924 Can be set to a boolean value to enable deep copies of structures.
925 Cross-referencing will then only be done when absolutely essential
926 (i.e., to break reference cycles). Default is 0.
930 $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
932 Can be set to a boolean value to control whether hash keys are quoted.
933 A false value will avoid quoting hash keys when it looks like a simple
934 string. Default is 1, which will always enclose hash keys in quotes.
938 $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
940 Can be set to a string that specifies an alternative to the C<bless>
941 builtin operator used to create objects. A function with the specified
942 name should exist, and should accept the same arguments as the builtin.
947 $Data::Dumper::Pair I<or> $I<OBJ>->Pair(I<[NEWVAL]>)
949 Can be set to a string that specifies the separator between hash keys
950 and values. To dump nested hash, array and scalar values to JavaScript,
951 use: C<$Data::Dumper::Pair = ' : ';>. Implementing C<bless> in JavaScript
952 is left as an exercise for the reader.
953 A function with the specified name exists, and accepts the same arguments
956 Default is: C< =E<gt> >.
960 $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
962 Can be set to a positive integer that specifies the depth beyond which
963 which we don't venture into a structure. Has no effect when
964 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
965 want to see more than enough). Default is 0, which means there is
970 $Data::Dumper::Useperl I<or> $I<OBJ>->Useperl(I<[NEWVAL]>)
972 Can be set to a boolean value which controls whether the pure Perl
973 implementation of C<Data::Dumper> is used. The C<Data::Dumper> module is
974 a dual implementation, with almost all functionality written in both
975 pure Perl and also in XS ('C'). Since the XS version is much faster, it
976 will always be used if possible. This option lets you override the
977 default behavior, usually for testing purposes only. Default is 0, which
978 means the XS implementation will be used if possible.
982 $Data::Dumper::Sortkeys I<or> $I<OBJ>->Sortkeys(I<[NEWVAL]>)
984 Can be set to a boolean value to control whether hash keys are dumped in
985 sorted order. A true value will cause the keys of all hashes to be
986 dumped in Perl's default sort order. Can also be set to a subroutine
987 reference which will be called for each hash that is dumped. In this
988 case C<Data::Dumper> will call the subroutine once for each hash,
989 passing it the reference of the hash. The purpose of the subroutine is
990 to return a reference to an array of the keys that will be dumped, in
991 the order that they should be dumped. Using this feature, you can
992 control both the order of the keys, and which keys are actually used. In
993 other words, this subroutine acts as a filter by which you can exclude
994 certain keys from being dumped. Default is 0, which means that hash keys
999 $Data::Dumper::Deparse I<or> $I<OBJ>->Deparse(I<[NEWVAL]>)
1001 Can be set to a boolean value to control whether code references are
1002 turned into perl source code. If set to a true value, C<B::Deparse>
1003 will be used to get the source of the code reference. Using this option
1004 will force using the Perl implementation of the dumper, since the fast
1005 XSUB implementation doesn't support it.
1007 Caution : use this option only if you know that your coderefs will be
1008 properly reconstructed by C<B::Deparse>.
1022 Run these code snippets to get a quick feel for the behavior of this
1023 module. When you are through with these examples, you may want to
1024 add or change the various configuration variables described above,
1025 to see their behavior. (See the testsuite in the Data::Dumper
1026 distribution for more examples.)
1032 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
1034 package Fuz; # a weird REF-REF-SCALAR object
1035 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
1040 $boo = [ 1, [], "abcd", \*foo,
1041 {1 => 'a', 023 => 'b', 0x45 => 'c'},
1042 \\"p\q\'r", $foo, $fuz];
1048 $bar = eval(Dumper($boo));
1050 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
1052 $Data::Dumper::Terse = 1; # don't output names where feasible
1053 $Data::Dumper::Indent = 0; # turn off all pretty print
1054 print Dumper($boo), "\n";
1056 $Data::Dumper::Indent = 1; # mild pretty print
1059 $Data::Dumper::Indent = 3; # pretty print with array indices
1062 $Data::Dumper::Useqq = 1; # print strings in double quotes
1065 $Data::Dumper::Pair = " : "; # specify hash key/value separator
1070 # recursive structures
1080 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
1083 $Data::Dumper::Purity = 1; # fill in the holes for eval
1084 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
1085 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
1088 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
1089 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1092 $Data::Dumper::Purity = 0; # avoid cross-refs
1093 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1105 print Data::Dumper->Dump([$f], [qw(f)]);
1107 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
1108 print Data::Dumper->Dump([$f], [qw(f)]);
1112 # object-oriented usage
1115 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
1116 $d->Seen({'*c' => $c}); # stash a ref without printing it
1119 $d->Reset->Purity(0); # empty the seen cache
1120 print join "----\n", $d->Dump;
1128 sub new { bless { state => 'awake' }, shift }
1131 print STDERR "preparing to sleep\n";
1132 $s->{state} = 'asleep';
1133 return bless $s, 'Foo::ZZZ';
1139 print STDERR "waking up\n";
1140 $s->{state} = 'awake';
1141 return bless $s, 'Foo';
1147 $b = Data::Dumper->new([$a], ['c']);
1148 $b->Freezer('Freeze');
1149 $b->Toaster('Thaw');
1153 print Data::Dumper->Dump([$d], ['d']);
1157 # symbol substitution (useful for recreating CODE refs)
1160 sub foo { print "foo speaking\n" }
1163 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1164 $d->Seen({ '*foo' => \&foo });
1169 # sorting and filtering hash keys
1172 $Data::Dumper::Sortkeys = \&my_filter;
1173 my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' };
1174 my $bar = { %$foo };
1175 my $baz = { reverse %$foo };
1176 print Dumper [ $foo, $bar, $baz ];
1180 # return an array ref containing the hash keys to dump
1181 # in the order that you want them to be dumped
1183 # Sort the keys of %$foo in reverse numeric order
1184 $hash eq $foo ? (sort {$b <=> $a} keys %$hash) :
1185 # Only dump the odd number keys of %$bar
1186 $hash eq $bar ? (grep {$_ % 2} keys %$hash) :
1187 # Sort keys in default order for all other hashes
1194 Due to limitations of Perl subroutine call semantics, you cannot pass an
1195 array or hash. Prepend it with a C<\> to pass its reference instead. This
1196 will be remedied in time, now that Perl has subroutine prototypes.
1197 For now, you need to use the extended usage form, and prepend the
1198 name with a C<*> to output it as a hash or array.
1200 C<Data::Dumper> cheats with CODE references. If a code reference is
1201 encountered in the structure being processed (and if you haven't set
1202 the C<Deparse> flag), an anonymous subroutine that
1203 contains the string '"DUMMY"' will be inserted in its place, and a warning
1204 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1205 in mind that the anonymous sub that gets created is just a placeholder.
1206 Someday, perl will have a switch to cache-on-demand the string
1207 representation of a compiled piece of code, I hope. If you have prior
1208 knowledge of all the code refs that your data structures are likely
1209 to have, you can use the C<Seen> method to pre-seed the internal reference
1210 table and make the dumped output point to them, instead. See L<EXAMPLES>
1213 The C<Useqq> and C<Deparse> flags makes Dump() run slower, since the
1214 XSUB implementation does not support them.
1216 SCALAR objects have the weirdest looking C<bless> workaround.
1218 Pure Perl version of C<Data::Dumper> escapes UTF-8 strings correctly
1219 only in Perl 5.8.0 and later.
1223 Starting from Perl 5.8.1 different runs of Perl will have different
1224 ordering of hash keys. The change was done for greater security,
1225 see L<perlsec/"Algorithmic Complexity Attacks">. This means that
1226 different runs of Perl will have different Data::Dumper outputs if
1227 the data contains hashes. If you need to have identical Data::Dumper
1228 outputs from different runs of Perl, use the environment variable
1229 PERL_HASH_SEED, see L<perlrun/PERL_HASH_SEED>. Using this restores
1230 the old (platform-specific) ordering: an even prettier solution might
1231 be to use the C<Sortkeys> filter of Data::Dumper.
1235 Gurusamy Sarathy gsar@activestate.com
1237 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1238 This program is free software; you can redistribute it and/or
1239 modify it under the same terms as Perl itself.
1243 Version 2.121 (Aug 24 2003)