4 # convert perl data structures into perl syntax suitable for both printing
7 # Documentation at the __END__
25 @EXPORT_OK = qw(DumperX);
27 XSLoader::load 'Data::Dumper';
29 # module vars and their defaults
30 $Indent = 2 unless defined $Indent;
31 $Purity = 0 unless defined $Purity;
32 $Pad = "" unless defined $Pad;
33 $Varname = "VAR" unless defined $Varname;
34 $Useqq = 0 unless defined $Useqq;
35 $Terse = 0 unless defined $Terse;
36 $Freezer = "" unless defined $Freezer;
37 $Toaster = "" unless defined $Toaster;
38 $Deepcopy = 0 unless defined $Deepcopy;
39 $Quotekeys = 1 unless defined $Quotekeys;
40 $Bless = "bless" unless defined $Bless;
41 #$Expdepth = 0 unless defined $Expdepth;
42 $Maxdepth = 0 unless defined $Maxdepth;
43 $Useperl = 0 unless defined $Useperl;
44 $Sortkeys = 0 unless defined $Sortkeys;
45 $Deparse = 0 unless defined $Deparse;
48 # expects an arrayref of values to be dumped.
49 # can optionally pass an arrayref of names for the values.
50 # names must have leading $ sign stripped. begin the name with *
51 # to cause output of arrays and hashes rather than refs.
56 croak "Usage: PACKAGE->new(ARRAYREF, [ARRAYREF])"
57 unless (defined($v) && (ref($v) eq 'ARRAY'));
58 $n = [] unless (defined($n) && (ref($v) eq 'ARRAY'));
61 level => 0, # current recursive depth
62 indent => $Indent, # various styles of indenting
63 pad => $Pad, # all lines prefixed by this string
64 xpad => "", # padding-per-level
65 apad => "", # added padding for hash keys n such
66 sep => "", # list separator
67 seen => {}, # local (nested) refs (id => [name, val])
68 todump => $v, # values to dump []
69 names => $n, # optional names for values []
70 varname => $Varname, # prefix to use for tagging nameless ones
71 purity => $Purity, # degree to which output is evalable
72 useqq => $Useqq, # use "" for strings (backslashitis ensues)
73 terse => $Terse, # avoid name output (where feasible)
74 freezer => $Freezer, # name of Freezer method for objects
75 toaster => $Toaster, # name of method to revive objects
76 deepcopy => $Deepcopy, # dont cross-ref, except to stop recursion
77 quotekeys => $Quotekeys, # quote hash keys
78 'bless' => $Bless, # keyword to use for "bless"
79 # expdepth => $Expdepth, # cutoff depth for explicit dumping
80 maxdepth => $Maxdepth, # depth beyond which we give up
81 useperl => $Useperl, # use the pure Perl implementation
82 sortkeys => $Sortkeys, # flag or filter for sorting hash keys
83 deparse => $Deparse, # use B::Deparse for coderefs
94 # add-to or query the table of already seen references
98 if (defined($g) && (ref($g) eq 'HASH')) {
100 while (($k, $v) = each %$g) {
101 if (defined $v and ref $v) {
102 ($id) = (overload::StrVal($v) =~ /\((.*)\)$/);
103 if ($k =~ /^[*](.*)$/) {
104 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
105 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
106 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
109 elsif ($k !~ /^\$/) {
112 $s->{seen}{$id} = [$k, $v];
115 carp "Only refs supported, ignoring non-ref item \$$k";
121 return map { @$_ } values %{$s->{seen}};
126 # set or query the values to be dumped
130 if (defined($v) && (ref($v) eq 'ARRAY')) {
131 $s->{todump} = [@$v]; # make a copy
135 return @{$s->{todump}};
140 # set or query the names of the values to be dumped
144 if (defined($n) && (ref($n) eq 'ARRAY')) {
145 $s->{names} = [@$n]; # make a copy
149 return @{$s->{names}};
157 unless $Data::Dumper::Useperl || (ref($_[0]) && $_[0]->{useperl}) ||
158 $Data::Dumper::Useqq || (ref($_[0]) && $_[0]->{useqq}) ||
159 $Data::Dumper::Deparse || (ref($_[0]) && $_[0]->{deparse});
164 # dump the refs in the current dumper object.
165 # expects same args as new() if called via package name.
169 my(@out, $val, $name);
173 $s = $s->new(@_) unless ref $s;
175 for $val (@{$s->{todump}}) {
178 $name = $s->{names}[$i++];
180 if ($name =~ /^[*](.*)$/) {
182 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
183 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
184 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
191 elsif ($name !~ /^\$/) {
192 $name = "\$" . $name;
196 $name = "\$" . $s->{varname} . $i;
201 local($s->{apad}) = $s->{apad};
202 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
203 $valstr = $s->_dump($val, $name);
206 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
207 $out .= $s->{pad} . $valstr . $s->{sep};
208 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
209 . ';' . $s->{sep} if @post;
213 return wantarray ? @out : join('', @out);
217 # twist, toil and turn;
218 # and recurse, of course.
219 # sometimes sordidly;
220 # and curse if no recourse.
223 my($s, $val, $name) = @_;
225 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
232 # prep it, if it looks like an object
233 if (my $freezer = $s->{freezer}) {
234 $val->$freezer() if UNIVERSAL::can($val, $freezer);
237 ($realpack, $realtype, $id) =
238 (overload::StrVal($val) =~ /^(?:(.*)\=)?([^=]*)\(([^\(]*)\)$/);
240 # if it has a name, we need to either look it up, or keep a tab
241 # on it so we know when we hit it later
242 if (defined($name) and length($name)) {
243 # keep a tab on it so that we dont fall into recursive pit
244 if (exists $s->{seen}{$id}) {
245 # if ($s->{expdepth} < $s->{level}) {
246 if ($s->{purity} and $s->{level} > 0) {
247 $out = ($realtype eq 'HASH') ? '{}' :
248 ($realtype eq 'ARRAY') ? '[]' :
250 push @post, $name . " = " . $s->{seen}{$id}[0];
253 $out = $s->{seen}{$id}[0];
254 if ($name =~ /^([\@\%])/) {
256 if ($out =~ /^\\$start/) {
257 $out = substr($out, 1);
260 $out = $start . '{' . $out . '}';
269 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
270 ($realtype eq 'CODE' and
271 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
277 if ($realpack and $realpack eq 'Regexp') {
283 # If purity is not set and maxdepth is set, then check depth:
284 # if we have reached maximum depth, return the string
285 # representation of the thing we are currently examining
286 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
288 and $s->{maxdepth} > 0
289 and $s->{level} >= $s->{maxdepth})
294 # we have a blessed ref
296 $out = $s->{'bless'} . '( ';
297 $blesspad = $s->{apad};
298 $s->{apad} .= ' ' if ($s->{indent} >= 2);
302 $ipad = $s->{xpad} x $s->{level};
304 if ($realtype eq 'SCALAR' || $realtype eq 'REF') {
306 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
309 $out .= '\\' . $s->_dump($$val, "\${$name}");
312 elsif ($realtype eq 'GLOB') {
313 $out .= '\\' . $s->_dump($$val, "*{$name}");
315 elsif ($realtype eq 'ARRAY') {
316 my($v, $pad, $mname);
318 $out .= ($name =~ /^\@/) ? '(' : '[';
319 $pad = $s->{sep} . $s->{pad} . $s->{apad};
320 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
321 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
322 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
323 ($mname = $name . '->');
324 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
326 $sname = $mname . '[' . $i . ']';
327 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
328 $out .= $pad . $ipad . $s->_dump($v, $sname);
329 $out .= "," if $i++ < $#$val;
331 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
332 $out .= ($name =~ /^\@/) ? ')' : ']';
334 elsif ($realtype eq 'HASH') {
335 my($k, $v, $pad, $lpad, $mname);
336 $out .= ($name =~ /^\%/) ? '(' : '{';
337 $pad = $s->{sep} . $s->{pad} . $s->{apad};
339 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
340 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
341 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
342 ($mname = $name . '->');
343 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
344 my ($sortkeys, $keys, $key) = ("$s->{sortkeys}");
346 if (ref($s->{sortkeys}) eq 'CODE') {
347 $keys = $s->{sortkeys}($val);
348 unless (ref($keys) eq 'ARRAY') {
349 carp "Sortkeys subroutine did not return ARRAYREF";
354 $keys = [ sort keys %$val ];
357 while (($k, $v) = ! $sortkeys ? (each %$val) :
358 @$keys ? ($key = shift(@$keys), $val->{$key}) :
361 my $nk = $s->_dump($k, "");
362 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
363 $sname = $mname . '{' . $nk . '}';
364 $out .= $pad . $ipad . $nk . " => ";
366 # temporarily alter apad
367 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
368 $out .= $s->_dump($val->{$k}, $sname) . ",";
369 $s->{apad} = $lpad if $s->{indent} >= 2;
371 if (substr($out, -1) eq ',') {
373 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
375 $out .= ($name =~ /^\%/) ? ')' : '}';
377 elsif ($realtype eq 'CODE') {
380 my $sub = 'sub ' . (B::Deparse->new)->coderef2text($val);
381 $pad = $s->{sep} . $s->{pad} . $s->{xpad} . $s->{apad} . ' ';
382 $sub =~ s/\n/$pad/gse;
385 $out .= 'sub { "DUMMY" }';
386 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
390 croak "Can\'t handle $realtype type.";
393 if ($realpack) { # we have a blessed ref
394 $out .= ', \'' . $realpack . '\'' . ' )';
395 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
396 $s->{apad} = $blesspad;
401 else { # simple scalar
404 # first, catalog the scalar
406 ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
407 if (exists $s->{seen}{$id}) {
408 if ($s->{seen}{$id}[2]) {
409 $out = $s->{seen}{$id}[0];
415 #warn "[>\\$name]\n";
416 $s->{seen}{$id} = ["\\$name", $ref];
419 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
420 my $name = substr($val, 1);
421 if ($name =~ /^[A-Za-z_][\w:]*$/) {
422 $name =~ s/^main::/::/;
426 $sname = $s->_dump($name, "");
427 $sname = '{' . $sname . '}';
431 local ($s->{level}) = 0;
432 for $k (qw(SCALAR ARRAY HASH)) {
433 my $gval = *$val{$k};
434 next unless defined $gval;
435 next if $k eq "SCALAR" && ! defined $$gval; # always there
437 # _dump can push into @post, so we hold our place using $postlen
438 my $postlen = scalar @post;
439 $post[$postlen] = "\*$sname = ";
440 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
441 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
444 $out .= '*' . $sname;
446 elsif (!defined($val)) {
449 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})$/) { # safe decimal number
454 $out .= qquote($val, $s->{useqq});
457 $val =~ s/([\\\'])/\\$1/g;
458 $out .= '\'' . $val . '\'';
463 # if we made it this far, $id was added to seen list at current
464 # level, so remove it to get deep copies
465 if ($s->{deepcopy}) {
466 delete($s->{seen}{$id});
469 $s->{seen}{$id}[2] = 1;
476 # non-OO style of earlier version
479 return Data::Dumper->Dump([@_]);
484 return Data::Dumper->Dumpxs([@_], []);
487 sub Dumpf { return Data::Dumper->Dump(@_) }
489 sub Dumpp { print Data::Dumper->Dump(@_) }
492 # reset the "seen" cache
521 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
526 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
531 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
536 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
541 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
546 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
551 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
556 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
561 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
566 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
571 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
576 defined($v) ? (($s->{'useperl'} = $v), return $s) : $s->{'useperl'};
581 defined($v) ? (($s->{'sortkeys'} = $v), return $s) : $s->{'sortkeys'};
586 defined($v) ? (($s->{'deparse'} = $v), return $s) : $s->{'deparse'};
589 # used by qquote below
600 # put a string value in double quotes
603 s/([\\\"\@\$])/\\$1/g;
604 my $bytes; { use bytes; $bytes = length }
605 s/([^\x00-\x7f])/'\x{'.sprintf("%x",ord($1)).'}'/ge if $bytes > length;
606 return qq("$_") unless
607 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
609 my $high = shift || "";
610 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
612 if (ord('^')==94) { # ascii
613 # no need for 3 digits in escape for these
614 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
615 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
616 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
617 if ($high eq "iso8859") {
618 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
619 } elsif ($high eq "utf8") {
621 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
622 } elsif ($high eq "8bit") {
625 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
629 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
630 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
631 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
632 {'\\'.sprintf('%03o',ord($1))}eg;
643 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
649 # simple procedural interface
650 print Dumper($foo, $bar);
652 # extended usage with names
653 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
655 # configuration variables
657 local $Data::Dump::Purity = 1;
658 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
662 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
666 $d->Purity(1)->Terse(1)->Deepcopy(1);
672 Given a list of scalars or reference variables, writes out their contents in
673 perl syntax. The references can also be objects. The contents of each
674 variable is output in a single Perl statement. Handles self-referential
675 structures correctly.
677 The return value can be C<eval>ed to get back an identical copy of the
678 original reference structure.
680 Any references that are the same as one of those passed in will be named
681 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
682 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
683 notation. You can specify names for individual values to be dumped if you
684 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
685 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
688 The default output of self-referential structures can be C<eval>ed, but the
689 nested references to C<$VAR>I<n> will be undefined, since a recursive
690 structure cannot be constructed using one Perl statement. You should set the
691 C<Purity> flag to 1 to get additional statements that will correctly fill in
694 In the extended usage form, the references to be dumped can be given
695 user-specified names. If a name begins with a C<*>, the output will
696 describe the dereferenced type of the supplied reference for hashes and
697 arrays, and coderefs. Output of names will be avoided where possible if
698 the C<Terse> flag is set.
700 In many cases, methods that are used to set the internal state of the
701 object will return the object itself, so method calls can be conveniently
704 Several styles of output are possible, all controlled by setting
705 the C<Indent> flag. See L<Configuration Variables or Methods> below
713 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
715 Returns a newly created C<Data::Dumper> object. The first argument is an
716 anonymous array of values to be dumped. The optional second argument is an
717 anonymous array of names for the values. The names need not have a leading
718 C<$> sign, and must be comprised of alphanumeric characters. You can begin
719 a name with a C<*> to specify that the dereferenced type must be dumped
720 instead of the reference itself, for ARRAY and HASH references.
722 The prefix specified by C<$Data::Dumper::Varname> will be used with a
723 numeric suffix if the name for a value is undefined.
725 Data::Dumper will catalog all references encountered while dumping the
726 values. Cross-references (in the form of names of substructures in perl
727 syntax) will be inserted at all possible points, preserving any structural
728 interdependencies in the original set of values. Structure traversal is
729 depth-first, and proceeds in order from the first supplied value to
732 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
734 Returns the stringified form of the values stored in the object (preserving
735 the order in which they were supplied to C<new>), subject to the
736 configuration options below. In a list context, it returns a list
737 of strings corresponding to the supplied values.
739 The second form, for convenience, simply calls the C<new> method on its
740 arguments before dumping the object immediately.
742 =item I<$OBJ>->Seen(I<[HASHREF]>)
744 Queries or adds to the internal table of already encountered references.
745 You must use C<Reset> to explicitly clear the table if needed. Such
746 references are not dumped; instead, their names are inserted wherever they
747 are encountered subsequently. This is useful especially for properly
748 dumping subroutine references.
750 Expects an anonymous hash of name => value pairs. Same rules apply for names
751 as in C<new>. If no argument is supplied, will return the "seen" list of
752 name => value pairs, in a list context. Otherwise, returns the object
755 =item I<$OBJ>->Values(I<[ARRAYREF]>)
757 Queries or replaces the internal array of values that will be dumped.
758 When called without arguments, returns the values. Otherwise, returns the
761 =item I<$OBJ>->Names(I<[ARRAYREF]>)
763 Queries or replaces the internal array of user supplied names for the values
764 that will be dumped. When called without arguments, returns the names.
765 Otherwise, returns the object itself.
769 Clears the internal table of "seen" references and returns the object
778 =item Dumper(I<LIST>)
780 Returns the stringified form of the values in the list, subject to the
781 configuration options below. The values will be named C<$VAR>I<n> in the
782 output, where I<n> is a numeric suffix. Will return a list of strings
787 =head2 Configuration Variables or Methods
789 Several configuration variables can be used to control the kind of output
790 generated when using the procedural interface. These variables are usually
791 C<local>ized in a block so that other parts of the code are not affected by
794 These variables determine the default state of the object created by calling
795 the C<new> method, but cannot be used to alter the state of the object
796 thereafter. The equivalent method names should be used instead to query
797 or set the internal state of the object.
799 The method forms return the object itself when called with arguments,
800 so that they can be chained together nicely.
804 =item $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
806 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
807 spews output without any newlines, indentation, or spaces between list
808 items. It is the most compact format possible that can still be called
809 valid perl. Style 1 outputs a readable form with newlines but no fancy
810 indentation (each level in the structure is simply indented by a fixed
811 amount of whitespace). Style 2 (the default) outputs a very readable form
812 which takes into account the length of hash keys (so the hash value lines
813 up). Style 3 is like style 2, but also annotates the elements of arrays
814 with their index (but the comment is on its own line, so array output
815 consumes twice the number of lines). Style 2 is the default.
817 =item $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
819 Controls the degree to which the output can be C<eval>ed to recreate the
820 supplied reference structures. Setting it to 1 will output additional perl
821 statements that will correctly recreate nested references. The default is
824 =item $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
826 Specifies the string that will be prefixed to every line of the output.
827 Empty string by default.
829 =item $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
831 Contains the prefix to use for tagging variable names in the output. The
834 =item $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
836 When set, enables the use of double quotes for representing string values.
837 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
838 characters will be backslashed, and unprintable characters will be output as
839 quoted octal integers. Since setting this variable imposes a performance
840 penalty, the default is 0. C<Dump()> will run slower if this flag is set,
841 since the fast XSUB implementation doesn't support it yet.
843 =item $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
845 When set, Data::Dumper will emit single, non-self-referential values as
846 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
847 will be avoided where possible, but be advised that such output may not
848 always be parseable by C<eval>.
850 =item $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
852 Can be set to a method name, or to an empty string to disable the feature.
853 Data::Dumper will invoke that method via the object before attempting to
854 stringify it. This method can alter the contents of the object (if, for
855 instance, it contains data allocated from C), and even rebless it in a
856 different package. The client is responsible for making sure the specified
857 method can be called via the object, and that the object ends up containing
858 only perl data types after the method has been called. Defaults to an empty
861 =item $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
863 Can be set to a method name, or to an empty string to disable the feature.
864 Data::Dumper will emit a method call for any objects that are to be dumped
865 using the syntax C<bless(DATA, CLASS)-E<gt>METHOD()>. Note that this means that
866 the method specified will have to perform any modifications required on the
867 object (like creating new state within it, and/or reblessing it in a
868 different package) and then return it. The client is responsible for making
869 sure the method can be called via the object, and that it returns a valid
870 object. Defaults to an empty string.
872 =item $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
874 Can be set to a boolean value to enable deep copies of structures.
875 Cross-referencing will then only be done when absolutely essential
876 (i.e., to break reference cycles). Default is 0.
878 =item $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
880 Can be set to a boolean value to control whether hash keys are quoted.
881 A false value will avoid quoting hash keys when it looks like a simple
882 string. Default is 1, which will always enclose hash keys in quotes.
884 =item $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
886 Can be set to a string that specifies an alternative to the C<bless>
887 builtin operator used to create objects. A function with the specified
888 name should exist, and should accept the same arguments as the builtin.
891 =item $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
893 Can be set to a positive integer that specifies the depth beyond which
894 which we don't venture into a structure. Has no effect when
895 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
896 want to see more than enough). Default is 0, which means there is
899 =item $Data::Dumper::Useperl I<or> $I<OBJ>->Useperl(I<[NEWVAL]>)
901 Can be set to a boolean value which controls whether the pure Perl
902 implementation of C<Data::Dumper> is used. The C<Data::Dumper> module is
903 a dual implementation, with almost all functionality written in both
904 pure Perl and also in XS ('C'). Since the XS version is much faster, it
905 will always be used if possible. This option lets you override the
906 default behavior, usually for testing purposes only. Default is 0, which
907 means the XS implementation will be used if possible.
909 =item $Data::Dumper::Sortkeys I<or> $I<OBJ>->Sortkeys(I<[NEWVAL]>)
911 Can be set to a boolean value to control whether hash keys are dumped in
912 sorted order. A true value will cause the keys of all hashes to be
913 dumped in Perl's default sort order. Can also be set to a subroutine
914 reference which will be called for each hash that is dumped. In this
915 case C<Data::Dumper> will call the subroutine once for each hash,
916 passing it the reference of the hash. The purpose of the subroutine is
917 to return a reference to an array of the keys that will be dumped, in
918 the order that they should be dumped. Using this feature, you can
919 control both the order of the keys, and which keys are actually used. In
920 other words, this subroutine acts as a filter by which you can exclude
921 certain keys from being dumped. Default is 0, which means that hash keys
924 =item $Data::Dumper::Deparse I<or> $I<OBJ>->Deparse(I<[NEWVAL]>)
926 Can be set to a boolean value to control whether code references are
927 turned into perl source code. If set to a true value, C<B::Deparse>
928 will be used to get the source of the code reference. Using this option
929 will force using the Perl implementation of the dumper, since the fast
930 XSUB implementation doesn't support it.
932 Caution : use this option only if you know that your coderefs will be
933 properly reconstructed by C<B::Deparse>.
947 Run these code snippets to get a quick feel for the behavior of this
948 module. When you are through with these examples, you may want to
949 add or change the various configuration variables described above,
950 to see their behavior. (See the testsuite in the Data::Dumper
951 distribution for more examples.)
957 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
959 package Fuz; # a weird REF-REF-SCALAR object
960 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
965 $boo = [ 1, [], "abcd", \*foo,
966 {1 => 'a', 023 => 'b', 0x45 => 'c'},
967 \\"p\q\'r", $foo, $fuz];
973 $bar = eval(Dumper($boo));
975 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
977 $Data::Dumper::Terse = 1; # don't output names where feasible
978 $Data::Dumper::Indent = 0; # turn off all pretty print
979 print Dumper($boo), "\n";
981 $Data::Dumper::Indent = 1; # mild pretty print
984 $Data::Dumper::Indent = 3; # pretty print with array indices
987 $Data::Dumper::Useqq = 1; # print strings in double quotes
992 # recursive structures
1002 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
1005 $Data::Dumper::Purity = 1; # fill in the holes for eval
1006 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
1007 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
1010 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
1011 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1014 $Data::Dumper::Purity = 0; # avoid cross-refs
1015 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1027 print Data::Dumper->Dump([$f], [qw(f)]);
1029 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
1030 print Data::Dumper->Dump([$f], [qw(f)]);
1034 # object-oriented usage
1037 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
1038 $d->Seen({'*c' => $c}); # stash a ref without printing it
1041 $d->Reset->Purity(0); # empty the seen cache
1042 print join "----\n", $d->Dump;
1050 sub new { bless { state => 'awake' }, shift }
1053 print STDERR "preparing to sleep\n";
1054 $s->{state} = 'asleep';
1055 return bless $s, 'Foo::ZZZ';
1061 print STDERR "waking up\n";
1062 $s->{state} = 'awake';
1063 return bless $s, 'Foo';
1069 $b = Data::Dumper->new([$a], ['c']);
1070 $b->Freezer('Freeze');
1071 $b->Toaster('Thaw');
1075 print Data::Dumper->Dump([$d], ['d']);
1079 # symbol substitution (useful for recreating CODE refs)
1082 sub foo { print "foo speaking\n" }
1085 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1086 $d->Seen({ '*foo' => \&foo });
1091 # sorting and filtering hash keys
1094 $Data::Dumper::Sortkeys = \&my_filter;
1095 my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' };
1096 my $bar = { %$foo };
1097 my $baz = { reverse %$foo };
1098 print Dumper [ $foo, $bar, $baz ];
1102 # return an array ref containing the hash keys to dump
1103 # in the order that you want them to be dumped
1105 # Sort the keys of %$foo in reverse numeric order
1106 $hash eq $foo ? (sort {$b <=> $a} keys %$hash) :
1107 # Only dump the odd number keys of %$bar
1108 $hash eq $bar ? (grep {$_ % 2} keys %$hash) :
1109 # Sort keys in default order for all other hashes
1116 Due to limitations of Perl subroutine call semantics, you cannot pass an
1117 array or hash. Prepend it with a C<\> to pass its reference instead. This
1118 will be remedied in time, now that Perl has subroutine prototypes.
1119 For now, you need to use the extended usage form, and prepend the
1120 name with a C<*> to output it as a hash or array.
1122 C<Data::Dumper> cheats with CODE references. If a code reference is
1123 encountered in the structure being processed (and if you haven't set
1124 the C<Deparse> flag), an anonymous subroutine that
1125 contains the string '"DUMMY"' will be inserted in its place, and a warning
1126 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1127 in mind that the anonymous sub that gets created is just a placeholder.
1128 Someday, perl will have a switch to cache-on-demand the string
1129 representation of a compiled piece of code, I hope. If you have prior
1130 knowledge of all the code refs that your data structures are likely
1131 to have, you can use the C<Seen> method to pre-seed the internal reference
1132 table and make the dumped output point to them, instead. See L<EXAMPLES>
1135 The C<Useqq> and C<Deparse> flags makes Dump() run slower, since the
1136 XSUB implementation does not support them.
1138 SCALAR objects have the weirdest looking C<bless> workaround.
1143 Gurusamy Sarathy gsar@activestate.com
1145 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1146 This program is free software; you can redistribute it and/or
1147 modify it under the same terms as Perl itself.
1152 Version 2.12 (unreleased)