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 $Pair = ' => ' unless defined $Pair;
44 $Useperl = 0 unless defined $Useperl;
45 $Sortkeys = 0 unless defined $Sortkeys;
46 $Deparse = 0 unless defined $Deparse;
49 # expects an arrayref of values to be dumped.
50 # can optionally pass an arrayref of names for the values.
51 # names must have leading $ sign stripped. begin the name with *
52 # to cause output of arrays and hashes rather than refs.
57 croak "Usage: PACKAGE->new(ARRAYREF, [ARRAYREF])"
58 unless (defined($v) && (ref($v) eq 'ARRAY'));
59 $n = [] unless (defined($n) && (ref($v) eq 'ARRAY'));
62 level => 0, # current recursive depth
63 indent => $Indent, # various styles of indenting
64 pad => $Pad, # all lines prefixed by this string
65 xpad => "", # padding-per-level
66 apad => "", # added padding for hash keys n such
67 sep => "", # list separator
68 pair => $Pair, # hash key/value separator: defaults to ' => '
69 seen => {}, # local (nested) refs (id => [name, val])
70 todump => $v, # values to dump []
71 names => $n, # optional names for values []
72 varname => $Varname, # prefix to use for tagging nameless ones
73 purity => $Purity, # degree to which output is evalable
74 useqq => $Useqq, # use "" for strings (backslashitis ensues)
75 terse => $Terse, # avoid name output (where feasible)
76 freezer => $Freezer, # name of Freezer method for objects
77 toaster => $Toaster, # name of method to revive objects
78 deepcopy => $Deepcopy, # dont cross-ref, except to stop recursion
79 quotekeys => $Quotekeys, # quote hash keys
80 'bless' => $Bless, # keyword to use for "bless"
81 # expdepth => $Expdepth, # cutoff depth for explicit dumping
82 maxdepth => $Maxdepth, # depth beyond which we give up
83 useperl => $Useperl, # use the pure Perl implementation
84 sortkeys => $Sortkeys, # flag or filter for sorting hash keys
85 deparse => $Deparse, # use B::Deparse for coderefs
96 # add-to or query the table of already seen references
100 if (defined($g) && (ref($g) eq 'HASH')) {
102 while (($k, $v) = each %$g) {
103 if (defined $v and ref $v) {
104 ($id) = (overload::StrVal($v) =~ /\((.*)\)$/);
105 if ($k =~ /^[*](.*)$/) {
106 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
107 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
108 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
111 elsif ($k !~ /^\$/) {
114 $s->{seen}{$id} = [$k, $v];
117 carp "Only refs supported, ignoring non-ref item \$$k";
123 return map { @$_ } values %{$s->{seen}};
128 # set or query the values to be dumped
132 if (defined($v) && (ref($v) eq 'ARRAY')) {
133 $s->{todump} = [@$v]; # make a copy
137 return @{$s->{todump}};
142 # set or query the names of the values to be dumped
146 if (defined($n) && (ref($n) eq 'ARRAY')) {
147 $s->{names} = [@$n]; # make a copy
151 return @{$s->{names}};
159 unless $Data::Dumper::Useperl || (ref($_[0]) && $_[0]->{useperl}) ||
160 $Data::Dumper::Useqq || (ref($_[0]) && $_[0]->{useqq}) ||
161 $Data::Dumper::Deparse || (ref($_[0]) && $_[0]->{deparse});
166 # dump the refs in the current dumper object.
167 # expects same args as new() if called via package name.
171 my(@out, $val, $name);
175 $s = $s->new(@_) unless ref $s;
177 for $val (@{$s->{todump}}) {
180 $name = $s->{names}[$i++];
182 if ($name =~ /^[*](.*)$/) {
184 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
185 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
186 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
193 elsif ($name !~ /^\$/) {
194 $name = "\$" . $name;
198 $name = "\$" . $s->{varname} . $i;
203 local($s->{apad}) = $s->{apad};
204 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
205 $valstr = $s->_dump($val, $name);
208 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
209 $out .= $s->{pad} . $valstr . $s->{sep};
210 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
211 . ';' . $s->{sep} if @post;
215 return wantarray ? @out : join('', @out);
219 # twist, toil and turn;
220 # and recurse, of course.
221 # sometimes sordidly;
222 # and curse if no recourse.
225 my($s, $val, $name) = @_;
227 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
234 # prep it, if it looks like an object
235 if (my $freezer = $s->{freezer}) {
236 $val->$freezer() if UNIVERSAL::can($val, $freezer);
239 ($realpack, $realtype, $id) =
240 (overload::StrVal($val) =~ /^(?:(.*)\=)?([^=]*)\(([^\(]*)\)$/);
242 # if it has a name, we need to either look it up, or keep a tab
243 # on it so we know when we hit it later
244 if (defined($name) and length($name)) {
245 # keep a tab on it so that we dont fall into recursive pit
246 if (exists $s->{seen}{$id}) {
247 # if ($s->{expdepth} < $s->{level}) {
248 if ($s->{purity} and $s->{level} > 0) {
249 $out = ($realtype eq 'HASH') ? '{}' :
250 ($realtype eq 'ARRAY') ? '[]' :
252 push @post, $name . " = " . $s->{seen}{$id}[0];
255 $out = $s->{seen}{$id}[0];
256 if ($name =~ /^([\@\%])/) {
258 if ($out =~ /^\\$start/) {
259 $out = substr($out, 1);
262 $out = $start . '{' . $out . '}';
271 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
272 ($realtype eq 'CODE' and
273 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
279 if ($realpack and $realpack eq 'Regexp') {
285 # If purity is not set and maxdepth is set, then check depth:
286 # if we have reached maximum depth, return the string
287 # representation of the thing we are currently examining
288 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
290 and $s->{maxdepth} > 0
291 and $s->{level} >= $s->{maxdepth})
296 # we have a blessed ref
298 $out = $s->{'bless'} . '( ';
299 $blesspad = $s->{apad};
300 $s->{apad} .= ' ' if ($s->{indent} >= 2);
304 $ipad = $s->{xpad} x $s->{level};
306 if ($realtype eq 'SCALAR' || $realtype eq 'REF') {
308 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
311 $out .= '\\' . $s->_dump($$val, "\${$name}");
314 elsif ($realtype eq 'GLOB') {
315 $out .= '\\' . $s->_dump($$val, "*{$name}");
317 elsif ($realtype eq 'ARRAY') {
318 my($v, $pad, $mname);
320 $out .= ($name =~ /^\@/) ? '(' : '[';
321 $pad = $s->{sep} . $s->{pad} . $s->{apad};
322 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
323 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
324 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
325 ($mname = $name . '->');
326 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
328 $sname = $mname . '[' . $i . ']';
329 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
330 $out .= $pad . $ipad . $s->_dump($v, $sname);
331 $out .= "," if $i++ < $#$val;
333 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
334 $out .= ($name =~ /^\@/) ? ')' : ']';
336 elsif ($realtype eq 'HASH') {
337 my($k, $v, $pad, $lpad, $mname, $pair);
338 $out .= ($name =~ /^\%/) ? '(' : '{';
339 $pad = $s->{sep} . $s->{pad} . $s->{apad};
342 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
343 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
344 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
345 ($mname = $name . '->');
346 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
347 my ($sortkeys, $keys, $key) = ("$s->{sortkeys}");
349 if (ref($s->{sortkeys}) eq 'CODE') {
350 $keys = $s->{sortkeys}($val);
351 unless (ref($keys) eq 'ARRAY') {
352 carp "Sortkeys subroutine did not return ARRAYREF";
357 $keys = [ sort keys %$val ];
360 while (($k, $v) = ! $sortkeys ? (each %$val) :
361 @$keys ? ($key = shift(@$keys), $val->{$key}) :
364 my $nk = $s->_dump($k, "");
365 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
366 $sname = $mname . '{' . $nk . '}';
367 $out .= $pad . $ipad . $nk . $pair;
369 # temporarily alter apad
370 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
371 $out .= $s->_dump($val->{$k}, $sname) . ",";
372 $s->{apad} = $lpad if $s->{indent} >= 2;
374 if (substr($out, -1) eq ',') {
376 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
378 $out .= ($name =~ /^\%/) ? ')' : '}';
380 elsif ($realtype eq 'CODE') {
383 my $sub = 'sub ' . (B::Deparse->new)->coderef2text($val);
384 $pad = $s->{sep} . $s->{pad} . $s->{xpad} . $s->{apad} . ' ';
385 $sub =~ s/\n/$pad/gse;
388 $out .= 'sub { "DUMMY" }';
389 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
393 croak "Can\'t handle $realtype type.";
396 if ($realpack) { # we have a blessed ref
397 $out .= ', \'' . $realpack . '\'' . ' )';
398 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
399 $s->{apad} = $blesspad;
404 else { # simple scalar
407 # first, catalog the scalar
409 ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
410 if (exists $s->{seen}{$id}) {
411 if ($s->{seen}{$id}[2]) {
412 $out = $s->{seen}{$id}[0];
418 #warn "[>\\$name]\n";
419 $s->{seen}{$id} = ["\\$name", $ref];
422 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
423 my $name = substr($val, 1);
424 if ($name =~ /^[A-Za-z_][\w:]*$/) {
425 $name =~ s/^main::/::/;
429 $sname = $s->_dump($name, "");
430 $sname = '{' . $sname . '}';
434 local ($s->{level}) = 0;
435 for $k (qw(SCALAR ARRAY HASH)) {
436 my $gval = *$val{$k};
437 next unless defined $gval;
438 next if $k eq "SCALAR" && ! defined $$gval; # always there
440 # _dump can push into @post, so we hold our place using $postlen
441 my $postlen = scalar @post;
442 $post[$postlen] = "\*$sname = ";
443 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
444 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
447 $out .= '*' . $sname;
449 elsif (!defined($val)) {
452 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})\z/) { # safe decimal number
456 if ($s->{useqq} or $val =~ tr/\0-\377//c) {
457 # Fall back to qq if there's unicode
458 $out .= qquote($val, $s->{useqq});
461 $val =~ s/([\\\'])/\\$1/g;
462 $out .= '\'' . $val . '\'';
467 # if we made it this far, $id was added to seen list at current
468 # level, so remove it to get deep copies
469 if ($s->{deepcopy}) {
470 delete($s->{seen}{$id});
473 $s->{seen}{$id}[2] = 1;
480 # non-OO style of earlier version
483 return Data::Dumper->Dump([@_]);
488 return Data::Dumper->Dumpxs([@_], []);
491 sub Dumpf { return Data::Dumper->Dump(@_) }
493 sub Dumpp { print Data::Dumper->Dump(@_) }
496 # reset the "seen" cache
525 defined($v) ? (($s->{pair} = $v), return $s) : $s->{pair};
530 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
535 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
540 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
545 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
550 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
555 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
560 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
565 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
570 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
575 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
580 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
585 defined($v) ? (($s->{'useperl'} = $v), return $s) : $s->{'useperl'};
590 defined($v) ? (($s->{'sortkeys'} = $v), return $s) : $s->{'sortkeys'};
595 defined($v) ? (($s->{'deparse'} = $v), return $s) : $s->{'deparse'};
598 # used by qquote below
609 # put a string value in double quotes
612 s/([\\\"\@\$])/\\$1/g;
613 my $bytes; { use bytes; $bytes = length }
614 s/([^\x00-\x7f])/'\x{'.sprintf("%x",ord($1)).'}'/ge if $bytes > length;
615 return qq("$_") unless
616 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
618 my $high = shift || "";
619 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
621 if (ord('^')==94) { # ascii
622 # no need for 3 digits in escape for these
623 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
624 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
625 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
626 if ($high eq "iso8859") {
627 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
628 } elsif ($high eq "utf8") {
630 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
631 } elsif ($high eq "8bit") {
634 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
635 s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
639 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
640 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
641 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
642 {'\\'.sprintf('%03o',ord($1))}eg;
653 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
659 # simple procedural interface
660 print Dumper($foo, $bar);
662 # extended usage with names
663 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
665 # configuration variables
667 local $Data::Dump::Purity = 1;
668 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
672 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
676 $d->Purity(1)->Terse(1)->Deepcopy(1);
682 Given a list of scalars or reference variables, writes out their contents in
683 perl syntax. The references can also be objects. The contents of each
684 variable is output in a single Perl statement. Handles self-referential
685 structures correctly.
687 The return value can be C<eval>ed to get back an identical copy of the
688 original reference structure.
690 Any references that are the same as one of those passed in will be named
691 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
692 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
693 notation. You can specify names for individual values to be dumped if you
694 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
695 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
698 The default output of self-referential structures can be C<eval>ed, but the
699 nested references to C<$VAR>I<n> will be undefined, since a recursive
700 structure cannot be constructed using one Perl statement. You should set the
701 C<Purity> flag to 1 to get additional statements that will correctly fill in
704 In the extended usage form, the references to be dumped can be given
705 user-specified names. If a name begins with a C<*>, the output will
706 describe the dereferenced type of the supplied reference for hashes and
707 arrays, and coderefs. Output of names will be avoided where possible if
708 the C<Terse> flag is set.
710 In many cases, methods that are used to set the internal state of the
711 object will return the object itself, so method calls can be conveniently
714 Several styles of output are possible, all controlled by setting
715 the C<Indent> flag. See L<Configuration Variables or Methods> below
723 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
725 Returns a newly created C<Data::Dumper> object. The first argument is an
726 anonymous array of values to be dumped. The optional second argument is an
727 anonymous array of names for the values. The names need not have a leading
728 C<$> sign, and must be comprised of alphanumeric characters. You can begin
729 a name with a C<*> to specify that the dereferenced type must be dumped
730 instead of the reference itself, for ARRAY and HASH references.
732 The prefix specified by C<$Data::Dumper::Varname> will be used with a
733 numeric suffix if the name for a value is undefined.
735 Data::Dumper will catalog all references encountered while dumping the
736 values. Cross-references (in the form of names of substructures in perl
737 syntax) will be inserted at all possible points, preserving any structural
738 interdependencies in the original set of values. Structure traversal is
739 depth-first, and proceeds in order from the first supplied value to
742 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
744 Returns the stringified form of the values stored in the object (preserving
745 the order in which they were supplied to C<new>), subject to the
746 configuration options below. In a list context, it returns a list
747 of strings corresponding to the supplied values.
749 The second form, for convenience, simply calls the C<new> method on its
750 arguments before dumping the object immediately.
752 =item I<$OBJ>->Seen(I<[HASHREF]>)
754 Queries or adds to the internal table of already encountered references.
755 You must use C<Reset> to explicitly clear the table if needed. Such
756 references are not dumped; instead, their names are inserted wherever they
757 are encountered subsequently. This is useful especially for properly
758 dumping subroutine references.
760 Expects an anonymous hash of name => value pairs. Same rules apply for names
761 as in C<new>. If no argument is supplied, will return the "seen" list of
762 name => value pairs, in a list context. Otherwise, returns the object
765 =item I<$OBJ>->Values(I<[ARRAYREF]>)
767 Queries or replaces the internal array of values that will be dumped.
768 When called without arguments, returns the values. Otherwise, returns the
771 =item I<$OBJ>->Names(I<[ARRAYREF]>)
773 Queries or replaces the internal array of user supplied names for the values
774 that will be dumped. When called without arguments, returns the names.
775 Otherwise, returns the object itself.
779 Clears the internal table of "seen" references and returns the object
788 =item Dumper(I<LIST>)
790 Returns the stringified form of the values in the list, subject to the
791 configuration options below. The values will be named C<$VAR>I<n> in the
792 output, where I<n> is a numeric suffix. Will return a list of strings
797 =head2 Configuration Variables or Methods
799 Several configuration variables can be used to control the kind of output
800 generated when using the procedural interface. These variables are usually
801 C<local>ized in a block so that other parts of the code are not affected by
804 These variables determine the default state of the object created by calling
805 the C<new> method, but cannot be used to alter the state of the object
806 thereafter. The equivalent method names should be used instead to query
807 or set the internal state of the object.
809 The method forms return the object itself when called with arguments,
810 so that they can be chained together nicely.
816 $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
818 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
819 spews output without any newlines, indentation, or spaces between list
820 items. It is the most compact format possible that can still be called
821 valid perl. Style 1 outputs a readable form with newlines but no fancy
822 indentation (each level in the structure is simply indented by a fixed
823 amount of whitespace). Style 2 (the default) outputs a very readable form
824 which takes into account the length of hash keys (so the hash value lines
825 up). Style 3 is like style 2, but also annotates the elements of arrays
826 with their index (but the comment is on its own line, so array output
827 consumes twice the number of lines). Style 2 is the default.
831 $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
833 Controls the degree to which the output can be C<eval>ed to recreate the
834 supplied reference structures. Setting it to 1 will output additional perl
835 statements that will correctly recreate nested references. The default is
840 $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
842 Specifies the string that will be prefixed to every line of the output.
843 Empty string by default.
847 $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
849 Contains the prefix to use for tagging variable names in the output. The
854 $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
856 When set, enables the use of double quotes for representing string values.
857 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
858 characters will be backslashed, and unprintable characters will be output as
859 quoted octal integers. Since setting this variable imposes a performance
860 penalty, the default is 0. C<Dump()> will run slower if this flag is set,
861 since the fast XSUB implementation doesn't support it yet.
865 $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
867 When set, Data::Dumper will emit single, non-self-referential values as
868 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
869 will be avoided where possible, but be advised that such output may not
870 always be parseable by C<eval>.
874 $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
876 Can be set to a method name, or to an empty string to disable the feature.
877 Data::Dumper will invoke that method via the object before attempting to
878 stringify it. This method can alter the contents of the object (if, for
879 instance, it contains data allocated from C), and even rebless it in a
880 different package. The client is responsible for making sure the specified
881 method can be called via the object, and that the object ends up containing
882 only perl data types after the method has been called. Defaults to an empty
887 $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
889 Can be set to a method name, or to an empty string to disable the feature.
890 Data::Dumper will emit a method call for any objects that are to be dumped
891 using the syntax C<bless(DATA, CLASS)-E<gt>METHOD()>. Note that this means that
892 the method specified will have to perform any modifications required on the
893 object (like creating new state within it, and/or reblessing it in a
894 different package) and then return it. The client is responsible for making
895 sure the method can be called via the object, and that it returns a valid
896 object. Defaults to an empty string.
900 $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
902 Can be set to a boolean value to enable deep copies of structures.
903 Cross-referencing will then only be done when absolutely essential
904 (i.e., to break reference cycles). Default is 0.
908 $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
910 Can be set to a boolean value to control whether hash keys are quoted.
911 A false value will avoid quoting hash keys when it looks like a simple
912 string. Default is 1, which will always enclose hash keys in quotes.
916 $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
918 Can be set to a string that specifies an alternative to the C<bless>
919 builtin operator used to create objects. A function with the specified
920 name should exist, and should accept the same arguments as the builtin.
925 $Data::Dumper::Pair I<or> $I<OBJ>->Pair(I<[NEWVAL]>)
927 Can be set to a string that specifies the separator between hash keys
928 and values. To dump nested hash, array and scalar values to JavaScript,
929 use: C<$Data::Dumper::Pair = ' : ';>. Implementing C<bless> in JavaScript
930 is left as an exercise for the reader.
931 A function with the specified name exists, and accepts the same arguments
934 Default is: C< =E<gt> >.
938 $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
940 Can be set to a positive integer that specifies the depth beyond which
941 which we don't venture into a structure. Has no effect when
942 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
943 want to see more than enough). Default is 0, which means there is
948 $Data::Dumper::Useperl I<or> $I<OBJ>->Useperl(I<[NEWVAL]>)
950 Can be set to a boolean value which controls whether the pure Perl
951 implementation of C<Data::Dumper> is used. The C<Data::Dumper> module is
952 a dual implementation, with almost all functionality written in both
953 pure Perl and also in XS ('C'). Since the XS version is much faster, it
954 will always be used if possible. This option lets you override the
955 default behavior, usually for testing purposes only. Default is 0, which
956 means the XS implementation will be used if possible.
960 $Data::Dumper::Sortkeys I<or> $I<OBJ>->Sortkeys(I<[NEWVAL]>)
962 Can be set to a boolean value to control whether hash keys are dumped in
963 sorted order. A true value will cause the keys of all hashes to be
964 dumped in Perl's default sort order. Can also be set to a subroutine
965 reference which will be called for each hash that is dumped. In this
966 case C<Data::Dumper> will call the subroutine once for each hash,
967 passing it the reference of the hash. The purpose of the subroutine is
968 to return a reference to an array of the keys that will be dumped, in
969 the order that they should be dumped. Using this feature, you can
970 control both the order of the keys, and which keys are actually used. In
971 other words, this subroutine acts as a filter by which you can exclude
972 certain keys from being dumped. Default is 0, which means that hash keys
977 $Data::Dumper::Deparse I<or> $I<OBJ>->Deparse(I<[NEWVAL]>)
979 Can be set to a boolean value to control whether code references are
980 turned into perl source code. If set to a true value, C<B::Deparse>
981 will be used to get the source of the code reference. Using this option
982 will force using the Perl implementation of the dumper, since the fast
983 XSUB implementation doesn't support it.
985 Caution : use this option only if you know that your coderefs will be
986 properly reconstructed by C<B::Deparse>.
1000 Run these code snippets to get a quick feel for the behavior of this
1001 module. When you are through with these examples, you may want to
1002 add or change the various configuration variables described above,
1003 to see their behavior. (See the testsuite in the Data::Dumper
1004 distribution for more examples.)
1010 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
1012 package Fuz; # a weird REF-REF-SCALAR object
1013 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
1018 $boo = [ 1, [], "abcd", \*foo,
1019 {1 => 'a', 023 => 'b', 0x45 => 'c'},
1020 \\"p\q\'r", $foo, $fuz];
1026 $bar = eval(Dumper($boo));
1028 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
1030 $Data::Dumper::Terse = 1; # don't output names where feasible
1031 $Data::Dumper::Indent = 0; # turn off all pretty print
1032 print Dumper($boo), "\n";
1034 $Data::Dumper::Indent = 1; # mild pretty print
1037 $Data::Dumper::Indent = 3; # pretty print with array indices
1040 $Data::Dumper::Useqq = 1; # print strings in double quotes
1043 $Data::Dumper::Pair = " : "; # specify hash key/value separator
1048 # recursive structures
1058 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
1061 $Data::Dumper::Purity = 1; # fill in the holes for eval
1062 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
1063 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
1066 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
1067 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1070 $Data::Dumper::Purity = 0; # avoid cross-refs
1071 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1083 print Data::Dumper->Dump([$f], [qw(f)]);
1085 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
1086 print Data::Dumper->Dump([$f], [qw(f)]);
1090 # object-oriented usage
1093 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
1094 $d->Seen({'*c' => $c}); # stash a ref without printing it
1097 $d->Reset->Purity(0); # empty the seen cache
1098 print join "----\n", $d->Dump;
1106 sub new { bless { state => 'awake' }, shift }
1109 print STDERR "preparing to sleep\n";
1110 $s->{state} = 'asleep';
1111 return bless $s, 'Foo::ZZZ';
1117 print STDERR "waking up\n";
1118 $s->{state} = 'awake';
1119 return bless $s, 'Foo';
1125 $b = Data::Dumper->new([$a], ['c']);
1126 $b->Freezer('Freeze');
1127 $b->Toaster('Thaw');
1131 print Data::Dumper->Dump([$d], ['d']);
1135 # symbol substitution (useful for recreating CODE refs)
1138 sub foo { print "foo speaking\n" }
1141 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1142 $d->Seen({ '*foo' => \&foo });
1147 # sorting and filtering hash keys
1150 $Data::Dumper::Sortkeys = \&my_filter;
1151 my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' };
1152 my $bar = { %$foo };
1153 my $baz = { reverse %$foo };
1154 print Dumper [ $foo, $bar, $baz ];
1158 # return an array ref containing the hash keys to dump
1159 # in the order that you want them to be dumped
1161 # Sort the keys of %$foo in reverse numeric order
1162 $hash eq $foo ? (sort {$b <=> $a} keys %$hash) :
1163 # Only dump the odd number keys of %$bar
1164 $hash eq $bar ? (grep {$_ % 2} keys %$hash) :
1165 # Sort keys in default order for all other hashes
1172 Due to limitations of Perl subroutine call semantics, you cannot pass an
1173 array or hash. Prepend it with a C<\> to pass its reference instead. This
1174 will be remedied in time, now that Perl has subroutine prototypes.
1175 For now, you need to use the extended usage form, and prepend the
1176 name with a C<*> to output it as a hash or array.
1178 C<Data::Dumper> cheats with CODE references. If a code reference is
1179 encountered in the structure being processed (and if you haven't set
1180 the C<Deparse> flag), an anonymous subroutine that
1181 contains the string '"DUMMY"' will be inserted in its place, and a warning
1182 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1183 in mind that the anonymous sub that gets created is just a placeholder.
1184 Someday, perl will have a switch to cache-on-demand the string
1185 representation of a compiled piece of code, I hope. If you have prior
1186 knowledge of all the code refs that your data structures are likely
1187 to have, you can use the C<Seen> method to pre-seed the internal reference
1188 table and make the dumped output point to them, instead. See L<EXAMPLES>
1191 The C<Useqq> and C<Deparse> flags makes Dump() run slower, since the
1192 XSUB implementation does not support them.
1194 SCALAR objects have the weirdest looking C<bless> workaround.
1199 Gurusamy Sarathy gsar@activestate.com
1201 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1202 This program is free software; you can redistribute it and/or
1203 modify it under the same terms as Perl itself.
1208 Version 2.12 (unreleased)