4 # convert perl data structures into perl syntax suitable for both printing
7 # Documentation at the __END__
12 $VERSION = $VERSION = '2.09';
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);
211 return "undef" unless defined $val;
218 # prep it, if it looks like an object
219 if ($type =~ /[a-z_:]/) {
220 my $freezer = $s->{freezer};
221 # UNIVERSAL::can should be used here, when we can require 5.004
223 eval { $val->$freezer() };
224 carp "WARNING(Freezer method call failed): $@" if $@;
228 ($realpack, $realtype, $id) =
229 (overload::StrVal($val) =~ /^(?:(.*)\=)?([^=]*)\(([^\(]*)\)$/);
231 # keep a tab on it so that we dont fall into recursive pit
232 if (exists $s->{seen}{$id}) {
233 # if ($s->{expdepth} < $s->{level}) {
234 if ($s->{purity} and $s->{level} > 0) {
235 $out = ($realtype eq 'HASH') ? '{}' :
236 ($realtype eq 'ARRAY') ? '[]' :
238 push @post, $name . " = " . $s->{seen}{$id}[0];
241 $out = $s->{seen}{$id}[0];
242 if ($name =~ /^([\@\%])/) {
244 if ($out =~ /^\\$start/) {
245 $out = substr($out, 1);
248 $out = $start . '{' . $out . '}';
257 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
258 ($realtype eq 'CODE' and
259 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
265 $ipad = $s->{xpad} x $s->{level};
267 if ($realpack) { # we have a blessed ref
268 $out = $s->{'bless'} . '( ';
269 $blesspad = $s->{apad};
270 $s->{apad} .= ' ' if ($s->{indent} >= 2);
273 if ($realtype eq 'SCALAR') {
275 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "") . ')}';
278 $out .= '\\' . $s->_dump($$val, "");
281 elsif ($realtype eq 'GLOB') {
282 $out .= '\\' . $s->_dump($$val, "");
284 elsif ($realtype eq 'ARRAY') {
285 my($v, $pad, $mname);
287 $out .= ($name =~ /^\@/) ? '(' : '[';
288 $pad = $s->{sep} . $s->{pad} . $s->{apad};
289 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
290 ($name =~ /[]}]$/) ? ($mname = $name) : ($mname = $name . '->');
291 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
293 $sname = $mname . '[' . $i . ']';
294 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
295 $out .= $pad . $ipad . $s->_dump($v, $sname);
296 $out .= "," if $i++ < $#$val;
298 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
299 $out .= ($name =~ /^\@/) ? ')' : ']';
301 elsif ($realtype eq 'HASH') {
302 my($k, $v, $pad, $lpad, $mname);
303 $out .= ($name =~ /^\%/) ? '(' : '{';
304 $pad = $s->{sep} . $s->{pad} . $s->{apad};
306 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
307 ($name =~ /[]}]$/) ? ($mname = $name) : ($mname = $name . '->');
308 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
309 while (($k, $v) = each %$val) {
310 my $nk = $s->_dump($k, "");
311 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
312 $sname = $mname . '{' . $nk . '}';
313 $out .= $pad . $ipad . $nk . " => ";
315 # temporarily alter apad
316 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
317 $out .= $s->_dump($val->{$k}, $sname) . ",";
318 $s->{apad} = $lpad if $s->{indent} >= 2;
320 if (substr($out, -1) eq ',') {
322 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
324 $out .= ($name =~ /^\%/) ? ')' : '}';
326 elsif ($realtype eq 'CODE') {
328 $out = 'sub { ' . $out . ' }';
329 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
332 croak "Can\'t handle $realtype type.";
335 if ($realpack) { # we have a blessed ref
336 $out .= ', \'' . $realpack . '\'' . ' )';
337 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
338 $s->{apad} = $blesspad;
343 else { # simple scalar
346 # first, catalog the scalar
348 ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
349 if (exists $s->{seen}{$id}) {
350 $out = $s->{seen}{$id}[0];
354 $s->{seen}{$id} = ["\\$name", $val];
357 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
358 my $name = substr($val, 1);
359 if ($name =~ /^[A-Za-z_][\w:]*$/) {
360 $name =~ s/^main::/::/;
364 $sname = $s->_dump($name, "");
365 $sname = '{' . $sname . '}';
369 local ($s->{level}) = 0;
370 for $k (qw(SCALAR ARRAY HASH)) {
371 # _dump can push into @post, so we hold our place using $postlen
372 my $postlen = scalar @post;
373 $post[$postlen] = "\*$sname = ";
374 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
375 $post[$postlen] .= $s->_dump(*{$name}{$k}, "\*$sname\{$k\}");
378 $out .= '*' . $sname;
380 elsif ($val =~ /^-?[1-9]\d{0,8}$/) { # safe decimal number
385 $out .= qquote($val);
388 $val =~ s/([\\\'])/\\$1/g;
389 $out .= '\'' . $val . '\'';
394 # if we made it this far, $id was added to seen list at current
395 # level, so remove it to get deep copies
396 delete($s->{seen}{$id}) if $id and $s->{deepcopy};
401 # non-OO style of earlier version
404 return Data::Dumper->Dump([@_]);
408 # same, only calls the XS version
411 return Data::Dumper->Dumpxs([@_], []);
414 sub Dumpf { return Data::Dumper->Dump(@_) }
416 sub Dumpp { print Data::Dumper->Dump(@_) }
419 # reset the "seen" cache
448 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
453 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
458 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
463 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
468 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
473 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
478 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
483 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
488 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
493 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
496 # put a string value in double quotes
499 s/([\\\"\@\$\%])/\\$1/g;
509 # s/([^\a\b\t\n\f\r\e\038-\176])/'\\'.sprintf('%03o',ord($1))/eg;
510 s/([\000-\006\013\016-\032\034-\037\177\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
519 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
526 # simple procedural interface
527 print Dumper($foo, $bar);
529 # extended usage with names
530 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
532 # configuration variables
534 local $Data::Dump::Purity = 1;
535 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
539 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
543 $d->Purity(1)->Terse(1)->Deepcopy(1);
549 Given a list of scalars or reference variables, writes out their contents in
550 perl syntax. The references can also be objects. The contents of each
551 variable is output in a single Perl statement. Handles self-referential
552 structures correctly.
554 The return value can be C<eval>ed to get back an identical copy of the
555 original reference structure.
557 Any references that are the same as one of those passed in will be named
558 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
559 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
560 notation. You can specify names for individual values to be dumped if you
561 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
562 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
565 The default output of self-referential structures can be C<eval>ed, but the
566 nested references to C<$VAR>I<n> will be undefined, since a recursive
567 structure cannot be constructed using one Perl statement. You should set the
568 C<Purity> flag to 1 to get additional statements that will correctly fill in
571 In the extended usage form, the references to be dumped can be given
572 user-specified names. If a name begins with a C<*>, the output will
573 describe the dereferenced type of the supplied reference for hashes and
574 arrays, and coderefs. Output of names will be avoided where possible if
575 the C<Terse> flag is set.
577 In many cases, methods that are used to set the internal state of the
578 object will return the object itself, so method calls can be conveniently
581 Several styles of output are possible, all controlled by setting
582 the C<Indent> flag. See L<Configuration Variables or Methods> below
590 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
592 Returns a newly created C<Data::Dumper> object. The first argument is an
593 anonymous array of values to be dumped. The optional second argument is an
594 anonymous array of names for the values. The names need not have a leading
595 C<$> sign, and must be comprised of alphanumeric characters. You can begin
596 a name with a C<*> to specify that the dereferenced type must be dumped
597 instead of the reference itself, for ARRAY and HASH references.
599 The prefix specified by C<$Data::Dumper::Varname> will be used with a
600 numeric suffix if the name for a value is undefined.
602 Data::Dumper will catalog all references encountered while dumping the
603 values. Cross-references (in the form of names of substructures in perl
604 syntax) will be inserted at all possible points, preserving any structural
605 interdependencies in the original set of values. Structure traversal is
606 depth-first, and proceeds in order from the first supplied value to
609 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
611 Returns the stringified form of the values stored in the object (preserving
612 the order in which they were supplied to C<new>), subject to the
613 configuration options below. In an array context, it returns a list
614 of strings corresponding to the supplied values.
616 The second form, for convenience, simply calls the C<new> method on its
617 arguments before dumping the object immediately.
619 =item I<$OBJ>->Dumpxs I<or> I<PACKAGE>->Dumpxs(I<ARRAYREF [>, I<ARRAYREF]>)
621 This method is available if you were able to compile and install the XSUB
622 extension to C<Data::Dumper>. It is exactly identical to the C<Dump> method
623 above, only about 4 to 5 times faster, since it is written entirely in C.
625 =item I<$OBJ>->Seen(I<[HASHREF]>)
627 Queries or adds to the internal table of already encountered references.
628 You must use C<Reset> to explicitly clear the table if needed. Such
629 references are not dumped; instead, their names are inserted wherever they
630 are encountered subsequently. This is useful especially for properly
631 dumping subroutine references.
633 Expects a anonymous hash of name => value pairs. Same rules apply for names
634 as in C<new>. If no argument is supplied, will return the "seen" list of
635 name => value pairs, in an array context. Otherwise, returns the object
638 =item I<$OBJ>->Values(I<[ARRAYREF]>)
640 Queries or replaces the internal array of values that will be dumped.
641 When called without arguments, returns the values. Otherwise, returns the
644 =item I<$OBJ>->Names(I<[ARRAYREF]>)
646 Queries or replaces the internal array of user supplied names for the values
647 that will be dumped. When called without arguments, returns the names.
648 Otherwise, returns the object itself.
652 Clears the internal table of "seen" references and returns the object
661 =item Dumper(I<LIST>)
663 Returns the stringified form of the values in the list, subject to the
664 configuration options below. The values will be named C<$VAR>I<n> in the
665 output, where I<n> is a numeric suffix. Will return a list of strings
668 =item DumperX(I<LIST>)
670 Identical to the C<Dumper()> function above, but this calls the XSUB
671 implementation. Only available if you were able to compile and install
672 the XSUB extensions in C<Data::Dumper>.
676 =head2 Configuration Variables or Methods
678 Several configuration variables can be used to control the kind of output
679 generated when using the procedural interface. These variables are usually
680 C<local>ized in a block so that other parts of the code are not affected by
683 These variables determine the default state of the object created by calling
684 the C<new> method, but cannot be used to alter the state of the object
685 thereafter. The equivalent method names should be used instead to query
686 or set the internal state of the object.
688 The method forms return the object itself when called with arguments,
689 so that they can be chained together nicely.
693 =item $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
695 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
696 spews output without any newlines, indentation, or spaces between list
697 items. It is the most compact format possible that can still be called
698 valid perl. Style 1 outputs a readable form with newlines but no fancy
699 indentation (each level in the structure is simply indented by a fixed
700 amount of whitespace). Style 2 (the default) outputs a very readable form
701 which takes into account the length of hash keys (so the hash value lines
702 up). Style 3 is like style 2, but also annotates the elements of arrays
703 with their index (but the comment is on its own line, so array output
704 consumes twice the number of lines). Style 2 is the default.
706 =item $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
708 Controls the degree to which the output can be C<eval>ed to recreate the
709 supplied reference structures. Setting it to 1 will output additional perl
710 statements that will correctly recreate nested references. The default is
713 =item $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
715 Specifies the string that will be prefixed to every line of the output.
716 Empty string by default.
718 =item $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
720 Contains the prefix to use for tagging variable names in the output. The
723 =item $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
725 When set, enables the use of double quotes for representing string values.
726 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
727 characters will be backslashed, and unprintable characters will be output as
728 quoted octal integers. Since setting this variable imposes a performance
729 penalty, the default is 0. The C<Dumpxs()> method does not honor this
732 =item $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
734 When set, Data::Dumper will emit single, non-self-referential values as
735 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
736 will be avoided where possible, but be advised that such output may not
737 always be parseable by C<eval>.
739 =item $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
741 Can be set to a method name, or to an empty string to disable the feature.
742 Data::Dumper will invoke that method via the object before attempting to
743 stringify it. This method can alter the contents of the object (if, for
744 instance, it contains data allocated from C), and even rebless it in a
745 different package. The client is responsible for making sure the specified
746 method can be called via the object, and that the object ends up containing
747 only perl data types after the method has been called. Defaults to an empty
750 =item $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
752 Can be set to a method name, or to an empty string to disable the feature.
753 Data::Dumper will emit a method call for any objects that are to be dumped
754 using the syntax C<bless(DATA, CLASS)->METHOD()>. Note that this means that
755 the method specified will have to perform any modifications required on the
756 object (like creating new state within it, and/or reblessing it in a
757 different package) and then return it. The client is responsible for making
758 sure the method can be called via the object, and that it returns a valid
759 object. Defaults to an empty string.
761 =item $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
763 Can be set to a boolean value to enable deep copies of structures.
764 Cross-referencing will then only be done when absolutely essential
765 (i.e., to break reference cycles). Default is 0.
767 =item $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
769 Can be set to a boolean value to control whether hash keys are quoted.
770 A false value will avoid quoting hash keys when it looks like a simple
771 string. Default is 1, which will always enclose hash keys in quotes.
773 =item $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
775 Can be set to a string that specifies an alternative to the C<bless>
776 builtin operator used to create objects. A function with the specified
777 name should exist, and should accept the same arguments as the builtin.
792 Run these code snippets to get a quick feel for the behavior of this
793 module. When you are through with these examples, you may want to
794 add or change the various configuration variables described above,
795 to see their behavior. (See the testsuite in the Data::Dumper
796 distribution for more examples.)
802 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
804 package Fuz; # a weird REF-REF-SCALAR object
805 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
810 $boo = [ 1, [], "abcd", \*foo,
811 {1 => 'a', 023 => 'b', 0x45 => 'c'},
812 \\"p\q\'r", $foo, $fuz];
818 $bar = eval(Dumper($boo));
820 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
822 $Data::Dumper::Terse = 1; # don't output names where feasible
823 $Data::Dumper::Indent = 0; # turn off all pretty print
824 print Dumper($boo), "\n";
826 $Data::Dumper::Indent = 1; # mild pretty print
829 $Data::Dumper::Indent = 3; # pretty print with array indices
832 $Data::Dumper::Useqq = 1; # print strings in double quotes
837 # recursive structures
847 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
850 $Data::Dumper::Purity = 1; # fill in the holes for eval
851 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
852 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
855 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
856 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
859 $Data::Dumper::Purity = 0; # avoid cross-refs
860 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
864 # object-oriented usage
867 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
868 $d->Seen({'*c' => $c}); # stash a ref without printing it
871 $d->Reset->Purity(0); # empty the seen cache
872 print join "----\n", $d->Dump;
880 sub new { bless { state => 'awake' }, shift }
883 print STDERR "preparing to sleep\n";
884 $s->{state} = 'asleep';
885 return bless $s, 'Foo::ZZZ';
891 print STDERR "waking up\n";
892 $s->{state} = 'awake';
893 return bless $s, 'Foo';
899 $b = Data::Dumper->new([$a], ['c']);
900 $b->Freezer('Freeze');
905 print Data::Dumper->Dump([$d], ['d']);
909 # symbol substitution (useful for recreating CODE refs)
912 sub foo { print "foo speaking\n" }
915 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
916 $d->Seen({ '*foo' => \&foo });
922 Due to limitations of Perl subroutine call semantics, you cannot pass an
923 array or hash. Prepend it with a C<\> to pass its reference instead. This
924 will be remedied in time, with the arrival of prototypes in later versions
925 of Perl. For now, you need to use the extended usage form, and prepend the
926 name with a C<*> to output it as a hash or array.
928 C<Data::Dumper> cheats with CODE references. If a code reference is
929 encountered in the structure being processed, an anonymous subroutine that
930 contains the string '"DUMMY"' will be inserted in its place, and a warning
931 will be printed if C<Purity> is set. You can C<eval> the result, but bear
932 in mind that the anonymous sub that gets created is just a placeholder.
933 Someday, perl will have a switch to cache-on-demand the string
934 representation of a compiled piece of code, I hope. If you have prior
935 knowledge of all the code refs that your data structures are likely
936 to have, you can use the C<Seen> method to pre-seed the internal reference
937 table and make the dumped output point to them, instead. See L<EXAMPLES>
940 The C<Useqq> flag is not honored by C<Dumpxs()> (it always outputs
941 strings in single quotes).
943 SCALAR objects have the weirdest looking C<bless> workaround.
948 Gurusamy Sarathy gsar@umich.edu
950 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
951 This program is free software; you can redistribute it and/or
952 modify it under the same terms as Perl itself.
957 Version 2.09 (9 July 1998)