4 # convert perl data structures into perl syntax suitable for both printing
7 # Documentation at the __END__
12 $VERSION = $VERSION = '2.101';
23 @ISA = qw(Exporter DynaLoader);
25 @EXPORT_OK = qw(DumperX);
27 bootstrap 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;
45 # expects an arrayref of values to be dumped.
46 # can optionally pass an arrayref of names for the values.
47 # names must have leading $ sign stripped. begin the name with *
48 # to cause output of arrays and hashes rather than refs.
53 croak "Usage: PACKAGE->new(ARRAYREF, [ARRAYREF])"
54 unless (defined($v) && (ref($v) eq 'ARRAY'));
55 $n = [] unless (defined($n) && (ref($v) eq 'ARRAY'));
58 level => 0, # current recursive depth
59 indent => $Indent, # various styles of indenting
60 pad => $Pad, # all lines prefixed by this string
61 xpad => "", # padding-per-level
62 apad => "", # added padding for hash keys n such
63 sep => "", # list separator
64 seen => {}, # local (nested) refs (id => [name, val])
65 todump => $v, # values to dump []
66 names => $n, # optional names for values []
67 varname => $Varname, # prefix to use for tagging nameless ones
68 purity => $Purity, # degree to which output is evalable
69 useqq => $Useqq, # use "" for strings (backslashitis ensues)
70 terse => $Terse, # avoid name output (where feasible)
71 freezer => $Freezer, # name of Freezer method for objects
72 toaster => $Toaster, # name of method to revive objects
73 deepcopy => $Deepcopy, # dont cross-ref, except to stop recursion
74 quotekeys => $Quotekeys, # quote hash keys
75 'bless' => $Bless, # keyword to use for "bless"
76 # expdepth => $Expdepth, # cutoff depth for explicit dumping
77 maxdepth => $Maxdepth, # depth beyond which we give up
88 # add-to or query the table of already seen references
92 if (defined($g) && (ref($g) eq 'HASH')) {
94 while (($k, $v) = each %$g) {
95 if (defined $v and ref $v) {
96 ($id) = (overload::StrVal($v) =~ /\((.*)\)$/);
97 if ($k =~ /^[*](.*)$/) {
98 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
99 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
100 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
103 elsif ($k !~ /^\$/) {
106 $s->{seen}{$id} = [$k, $v];
109 carp "Only refs supported, ignoring non-ref item \$$k";
115 return map { @$_ } values %{$s->{seen}};
120 # set or query the values to be dumped
124 if (defined($v) && (ref($v) eq 'ARRAY')) {
125 $s->{todump} = [@$v]; # make a copy
129 return @{$s->{todump}};
134 # set or query the names of the values to be dumped
138 if (defined($n) && (ref($n) eq 'ARRAY')) {
139 $s->{names} = [@$n]; # make a copy
143 return @{$s->{names}};
150 # dump the refs in the current dumper object.
151 # expects same args as new() if called via package name.
155 my(@out, $val, $name);
159 $s = $s->new(@_) unless ref $s;
161 for $val (@{$s->{todump}}) {
164 $name = $s->{names}[$i++];
166 if ($name =~ /^[*](.*)$/) {
168 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
169 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
170 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
177 elsif ($name !~ /^\$/) {
178 $name = "\$" . $name;
182 $name = "\$" . $s->{varname} . $i;
187 local($s->{apad}) = $s->{apad};
188 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
189 $valstr = $s->_dump($val, $name);
192 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
193 $out .= $s->{pad} . $valstr . $s->{sep};
194 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
195 . ';' . $s->{sep} if @post;
199 return wantarray ? @out : join('', @out);
203 # twist, toil and turn;
204 # and recurse, of course.
207 my($s, $val, $name) = @_;
209 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
216 # prep it, if it looks like an object
217 if (my $freezer = $s->{freezer}) {
218 $val->$freezer() if UNIVERSAL::can($val, $freezer);
221 ($realpack, $realtype, $id) =
222 (overload::StrVal($val) =~ /^(?:(.*)\=)?([^=]*)\(([^\(]*)\)$/);
224 # if it has a name, we need to either look it up, or keep a tab
225 # on it so we know when we hit it later
226 if (defined($name) and length($name)) {
227 # keep a tab on it so that we dont fall into recursive pit
228 if (exists $s->{seen}{$id}) {
229 # if ($s->{expdepth} < $s->{level}) {
230 if ($s->{purity} and $s->{level} > 0) {
231 $out = ($realtype eq 'HASH') ? '{}' :
232 ($realtype eq 'ARRAY') ? '[]' :
234 push @post, $name . " = " . $s->{seen}{$id}[0];
237 $out = $s->{seen}{$id}[0];
238 if ($name =~ /^([\@\%])/) {
240 if ($out =~ /^\\$start/) {
241 $out = substr($out, 1);
244 $out = $start . '{' . $out . '}';
253 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
254 ($realtype eq 'CODE' and
255 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
261 if ($realpack and $realpack eq 'Regexp') {
267 # If purity is not set and maxdepth is set, then check depth:
268 # if we have reached maximum depth, return the string
269 # representation of the thing we are currently examining
270 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
272 and $s->{maxdepth} > 0
273 and $s->{level} >= $s->{maxdepth})
278 # we have a blessed ref
280 $out = $s->{'bless'} . '( ';
281 $blesspad = $s->{apad};
282 $s->{apad} .= ' ' if ($s->{indent} >= 2);
286 $ipad = $s->{xpad} x $s->{level};
289 if ($realtype eq 'SCALAR') {
291 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
294 $out .= '\\' . $s->_dump($$val, "\${$name}");
297 elsif ($realtype eq 'GLOB') {
298 $out .= '\\' . $s->_dump($$val, "*{$name}");
300 elsif ($realtype eq 'ARRAY') {
301 my($v, $pad, $mname);
303 $out .= ($name =~ /^\@/) ? '(' : '[';
304 $pad = $s->{sep} . $s->{pad} . $s->{apad};
305 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
306 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
307 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
308 ($mname = $name . '->');
309 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
311 $sname = $mname . '[' . $i . ']';
312 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
313 $out .= $pad . $ipad . $s->_dump($v, $sname);
314 $out .= "," if $i++ < $#$val;
316 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
317 $out .= ($name =~ /^\@/) ? ')' : ']';
319 elsif ($realtype eq 'HASH') {
320 my($k, $v, $pad, $lpad, $mname);
321 $out .= ($name =~ /^\%/) ? '(' : '{';
322 $pad = $s->{sep} . $s->{pad} . $s->{apad};
324 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
325 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
326 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
327 ($mname = $name . '->');
328 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
329 while (($k, $v) = each %$val) {
330 my $nk = $s->_dump($k, "");
331 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
332 $sname = $mname . '{' . $nk . '}';
333 $out .= $pad . $ipad . $nk . " => ";
335 # temporarily alter apad
336 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
337 $out .= $s->_dump($val->{$k}, $sname) . ",";
338 $s->{apad} = $lpad if $s->{indent} >= 2;
340 if (substr($out, -1) eq ',') {
342 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
344 $out .= ($name =~ /^\%/) ? ')' : '}';
346 elsif ($realtype eq 'CODE') {
347 $out .= 'sub { "DUMMY" }';
348 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
351 croak "Can\'t handle $realtype type.";
354 if ($realpack) { # we have a blessed ref
355 $out .= ', \'' . $realpack . '\'' . ' )';
356 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
357 $s->{apad} = $blesspad;
362 else { # simple scalar
365 # first, catalog the scalar
367 ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
368 if (exists $s->{seen}{$id}) {
369 if ($s->{seen}{$id}[2]) {
370 $out = $s->{seen}{$id}[0];
376 #warn "[>\\$name]\n";
377 $s->{seen}{$id} = ["\\$name", $ref];
380 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
381 my $name = substr($val, 1);
382 if ($name =~ /^[A-Za-z_][\w:]*$/) {
383 $name =~ s/^main::/::/;
387 $sname = $s->_dump($name, "");
388 $sname = '{' . $sname . '}';
392 local ($s->{level}) = 0;
393 for $k (qw(SCALAR ARRAY HASH)) {
394 my $gval = *$val{$k};
395 next unless defined $gval;
396 next if $k eq "SCALAR" && ! defined $$gval; # always there
398 # _dump can push into @post, so we hold our place using $postlen
399 my $postlen = scalar @post;
400 $post[$postlen] = "\*$sname = ";
401 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
402 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
405 $out .= '*' . $sname;
407 elsif (!defined($val)) {
410 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})$/) { # safe decimal number
415 $out .= qquote($val, $s->{useqq});
418 $val =~ s/([\\\'])/\\$1/g;
419 $out .= '\'' . $val . '\'';
424 # if we made it this far, $id was added to seen list at current
425 # level, so remove it to get deep copies
426 if ($s->{deepcopy}) {
427 delete($s->{seen}{$id});
430 $s->{seen}{$id}[2] = 1;
437 # non-OO style of earlier version
440 return Data::Dumper->Dump([@_]);
444 # same, only calls the XS version
447 return Data::Dumper->Dumpxs([@_], []);
450 sub Dumpf { return Data::Dumper->Dump(@_) }
452 sub Dumpp { print Data::Dumper->Dump(@_) }
455 # reset the "seen" cache
484 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
489 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
494 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
499 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
504 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
509 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
514 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
519 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
524 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
529 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
534 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
538 # used by qquote below
549 # put a string value in double quotes
552 s/([\\\"\@\$])/\\$1/g;
553 return qq("$_") unless /[^\040-\176]/; # fast exit
555 my $high = shift || "";
556 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
558 # no need for 3 digits in escape for these
559 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
561 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
562 if ($high eq "iso8859") {
563 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
564 } elsif ($high eq "utf8") {
566 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
567 } elsif ($high eq "8bit") {
570 s/([\0-\037\177-\377])/'\\'.sprintf('%03o',ord($1))/eg;
580 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
587 # simple procedural interface
588 print Dumper($foo, $bar);
590 # extended usage with names
591 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
593 # configuration variables
595 local $Data::Dump::Purity = 1;
596 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
600 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
604 $d->Purity(1)->Terse(1)->Deepcopy(1);
610 Given a list of scalars or reference variables, writes out their contents in
611 perl syntax. The references can also be objects. The contents of each
612 variable is output in a single Perl statement. Handles self-referential
613 structures correctly.
615 The return value can be C<eval>ed to get back an identical copy of the
616 original reference structure.
618 Any references that are the same as one of those passed in will be named
619 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
620 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
621 notation. You can specify names for individual values to be dumped if you
622 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
623 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
626 The default output of self-referential structures can be C<eval>ed, but the
627 nested references to C<$VAR>I<n> will be undefined, since a recursive
628 structure cannot be constructed using one Perl statement. You should set the
629 C<Purity> flag to 1 to get additional statements that will correctly fill in
632 In the extended usage form, the references to be dumped can be given
633 user-specified names. If a name begins with a C<*>, the output will
634 describe the dereferenced type of the supplied reference for hashes and
635 arrays, and coderefs. Output of names will be avoided where possible if
636 the C<Terse> flag is set.
638 In many cases, methods that are used to set the internal state of the
639 object will return the object itself, so method calls can be conveniently
642 Several styles of output are possible, all controlled by setting
643 the C<Indent> flag. See L<Configuration Variables or Methods> below
651 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
653 Returns a newly created C<Data::Dumper> object. The first argument is an
654 anonymous array of values to be dumped. The optional second argument is an
655 anonymous array of names for the values. The names need not have a leading
656 C<$> sign, and must be comprised of alphanumeric characters. You can begin
657 a name with a C<*> to specify that the dereferenced type must be dumped
658 instead of the reference itself, for ARRAY and HASH references.
660 The prefix specified by C<$Data::Dumper::Varname> will be used with a
661 numeric suffix if the name for a value is undefined.
663 Data::Dumper will catalog all references encountered while dumping the
664 values. Cross-references (in the form of names of substructures in perl
665 syntax) will be inserted at all possible points, preserving any structural
666 interdependencies in the original set of values. Structure traversal is
667 depth-first, and proceeds in order from the first supplied value to
670 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
672 Returns the stringified form of the values stored in the object (preserving
673 the order in which they were supplied to C<new>), subject to the
674 configuration options below. In an array context, it returns a list
675 of strings corresponding to the supplied values.
677 The second form, for convenience, simply calls the C<new> method on its
678 arguments before dumping the object immediately.
680 =item I<$OBJ>->Dumpxs I<or> I<PACKAGE>->Dumpxs(I<ARRAYREF [>, I<ARRAYREF]>)
682 This method is available if you were able to compile and install the XSUB
683 extension to C<Data::Dumper>. It is exactly identical to the C<Dump> method
684 above, only about 4 to 5 times faster, since it is written entirely in C.
686 =item I<$OBJ>->Seen(I<[HASHREF]>)
688 Queries or adds to the internal table of already encountered references.
689 You must use C<Reset> to explicitly clear the table if needed. Such
690 references are not dumped; instead, their names are inserted wherever they
691 are encountered subsequently. This is useful especially for properly
692 dumping subroutine references.
694 Expects a anonymous hash of name => value pairs. Same rules apply for names
695 as in C<new>. If no argument is supplied, will return the "seen" list of
696 name => value pairs, in an array context. Otherwise, returns the object
699 =item I<$OBJ>->Values(I<[ARRAYREF]>)
701 Queries or replaces the internal array of values that will be dumped.
702 When called without arguments, returns the values. Otherwise, returns the
705 =item I<$OBJ>->Names(I<[ARRAYREF]>)
707 Queries or replaces the internal array of user supplied names for the values
708 that will be dumped. When called without arguments, returns the names.
709 Otherwise, returns the object itself.
713 Clears the internal table of "seen" references and returns the object
722 =item Dumper(I<LIST>)
724 Returns the stringified form of the values in the list, subject to the
725 configuration options below. The values will be named C<$VAR>I<n> in the
726 output, where I<n> is a numeric suffix. Will return a list of strings
729 =item DumperX(I<LIST>)
731 Identical to the C<Dumper()> function above, but this calls the XSUB
732 implementation. Only available if you were able to compile and install
733 the XSUB extensions in C<Data::Dumper>.
737 =head2 Configuration Variables or Methods
739 Several configuration variables can be used to control the kind of output
740 generated when using the procedural interface. These variables are usually
741 C<local>ized in a block so that other parts of the code are not affected by
744 These variables determine the default state of the object created by calling
745 the C<new> method, but cannot be used to alter the state of the object
746 thereafter. The equivalent method names should be used instead to query
747 or set the internal state of the object.
749 The method forms return the object itself when called with arguments,
750 so that they can be chained together nicely.
754 =item $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
756 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
757 spews output without any newlines, indentation, or spaces between list
758 items. It is the most compact format possible that can still be called
759 valid perl. Style 1 outputs a readable form with newlines but no fancy
760 indentation (each level in the structure is simply indented by a fixed
761 amount of whitespace). Style 2 (the default) outputs a very readable form
762 which takes into account the length of hash keys (so the hash value lines
763 up). Style 3 is like style 2, but also annotates the elements of arrays
764 with their index (but the comment is on its own line, so array output
765 consumes twice the number of lines). Style 2 is the default.
767 =item $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
769 Controls the degree to which the output can be C<eval>ed to recreate the
770 supplied reference structures. Setting it to 1 will output additional perl
771 statements that will correctly recreate nested references. The default is
774 =item $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
776 Specifies the string that will be prefixed to every line of the output.
777 Empty string by default.
779 =item $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
781 Contains the prefix to use for tagging variable names in the output. The
784 =item $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
786 When set, enables the use of double quotes for representing string values.
787 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
788 characters will be backslashed, and unprintable characters will be output as
789 quoted octal integers. Since setting this variable imposes a performance
790 penalty, the default is 0. The C<Dumpxs()> method does not honor this
793 =item $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
795 When set, Data::Dumper will emit single, non-self-referential values as
796 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
797 will be avoided where possible, but be advised that such output may not
798 always be parseable by C<eval>.
800 =item $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
802 Can be set to a method name, or to an empty string to disable the feature.
803 Data::Dumper will invoke that method via the object before attempting to
804 stringify it. This method can alter the contents of the object (if, for
805 instance, it contains data allocated from C), and even rebless it in a
806 different package. The client is responsible for making sure the specified
807 method can be called via the object, and that the object ends up containing
808 only perl data types after the method has been called. Defaults to an empty
811 =item $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
813 Can be set to a method name, or to an empty string to disable the feature.
814 Data::Dumper will emit a method call for any objects that are to be dumped
815 using the syntax C<bless(DATA, CLASS)->METHOD()>. Note that this means that
816 the method specified will have to perform any modifications required on the
817 object (like creating new state within it, and/or reblessing it in a
818 different package) and then return it. The client is responsible for making
819 sure the method can be called via the object, and that it returns a valid
820 object. Defaults to an empty string.
822 =item $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
824 Can be set to a boolean value to enable deep copies of structures.
825 Cross-referencing will then only be done when absolutely essential
826 (i.e., to break reference cycles). Default is 0.
828 =item $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
830 Can be set to a boolean value to control whether hash keys are quoted.
831 A false value will avoid quoting hash keys when it looks like a simple
832 string. Default is 1, which will always enclose hash keys in quotes.
834 =item $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
836 Can be set to a string that specifies an alternative to the C<bless>
837 builtin operator used to create objects. A function with the specified
838 name should exist, and should accept the same arguments as the builtin.
841 =item $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
843 Can be set to a positive integer that specifies the depth beyond which
844 which we don't venture into a structure. Has no effect when
845 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
846 want to see more than enough). Default is 0, which means there is
861 Run these code snippets to get a quick feel for the behavior of this
862 module. When you are through with these examples, you may want to
863 add or change the various configuration variables described above,
864 to see their behavior. (See the testsuite in the Data::Dumper
865 distribution for more examples.)
871 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
873 package Fuz; # a weird REF-REF-SCALAR object
874 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
879 $boo = [ 1, [], "abcd", \*foo,
880 {1 => 'a', 023 => 'b', 0x45 => 'c'},
881 \\"p\q\'r", $foo, $fuz];
887 $bar = eval(Dumper($boo));
889 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
891 $Data::Dumper::Terse = 1; # don't output names where feasible
892 $Data::Dumper::Indent = 0; # turn off all pretty print
893 print Dumper($boo), "\n";
895 $Data::Dumper::Indent = 1; # mild pretty print
898 $Data::Dumper::Indent = 3; # pretty print with array indices
901 $Data::Dumper::Useqq = 1; # print strings in double quotes
906 # recursive structures
916 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
919 $Data::Dumper::Purity = 1; # fill in the holes for eval
920 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
921 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
924 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
925 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
928 $Data::Dumper::Purity = 0; # avoid cross-refs
929 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
941 print Data::Dumper->Dump([$f], [qw(f)]);
943 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
944 print Data::Dumper->Dump([$f], [qw(f)]);
948 # object-oriented usage
951 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
952 $d->Seen({'*c' => $c}); # stash a ref without printing it
955 $d->Reset->Purity(0); # empty the seen cache
956 print join "----\n", $d->Dump;
964 sub new { bless { state => 'awake' }, shift }
967 print STDERR "preparing to sleep\n";
968 $s->{state} = 'asleep';
969 return bless $s, 'Foo::ZZZ';
975 print STDERR "waking up\n";
976 $s->{state} = 'awake';
977 return bless $s, 'Foo';
983 $b = Data::Dumper->new([$a], ['c']);
984 $b->Freezer('Freeze');
989 print Data::Dumper->Dump([$d], ['d']);
993 # symbol substitution (useful for recreating CODE refs)
996 sub foo { print "foo speaking\n" }
999 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1000 $d->Seen({ '*foo' => \&foo });
1006 Due to limitations of Perl subroutine call semantics, you cannot pass an
1007 array or hash. Prepend it with a C<\> to pass its reference instead. This
1008 will be remedied in time, with the arrival of prototypes in later versions
1009 of Perl. For now, you need to use the extended usage form, and prepend the
1010 name with a C<*> to output it as a hash or array.
1012 C<Data::Dumper> cheats with CODE references. If a code reference is
1013 encountered in the structure being processed, an anonymous subroutine that
1014 contains the string '"DUMMY"' will be inserted in its place, and a warning
1015 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1016 in mind that the anonymous sub that gets created is just a placeholder.
1017 Someday, perl will have a switch to cache-on-demand the string
1018 representation of a compiled piece of code, I hope. If you have prior
1019 knowledge of all the code refs that your data structures are likely
1020 to have, you can use the C<Seen> method to pre-seed the internal reference
1021 table and make the dumped output point to them, instead. See L<EXAMPLES>
1024 The C<Useqq> flag is not honored by C<Dumpxs()> (it always outputs
1025 strings in single quotes).
1027 SCALAR objects have the weirdest looking C<bless> workaround.
1032 Gurusamy Sarathy gsar@activestate.com
1034 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1035 This program is free software; you can redistribute it and/or
1036 modify it under the same terms as Perl itself.
1041 Version 2.11 (unreleased)