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;
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}};
151 unless $Data::Dumper::Useqq || (ref($_[0]) && $_[0]->{useqq});
156 # dump the refs in the current dumper object.
157 # expects same args as new() if called via package name.
161 my(@out, $val, $name);
165 $s = $s->new(@_) unless ref $s;
167 for $val (@{$s->{todump}}) {
170 $name = $s->{names}[$i++];
172 if ($name =~ /^[*](.*)$/) {
174 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
175 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
176 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
183 elsif ($name !~ /^\$/) {
184 $name = "\$" . $name;
188 $name = "\$" . $s->{varname} . $i;
193 local($s->{apad}) = $s->{apad};
194 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
195 $valstr = $s->_dump($val, $name);
198 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
199 $out .= $s->{pad} . $valstr . $s->{sep};
200 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
201 . ';' . $s->{sep} if @post;
205 return wantarray ? @out : join('', @out);
209 # twist, toil and turn;
210 # and recurse, of course.
213 my($s, $val, $name) = @_;
215 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
222 # prep it, if it looks like an object
223 if (my $freezer = $s->{freezer}) {
224 $val->$freezer() if UNIVERSAL::can($val, $freezer);
227 ($realpack, $realtype, $id) =
228 (overload::StrVal($val) =~ /^(?:(.*)\=)?([^=]*)\(([^\(]*)\)$/);
230 # if it has a name, we need to either look it up, or keep a tab
231 # on it so we know when we hit it later
232 if (defined($name) and length($name)) {
233 # keep a tab on it so that we dont fall into recursive pit
234 if (exists $s->{seen}{$id}) {
235 # if ($s->{expdepth} < $s->{level}) {
236 if ($s->{purity} and $s->{level} > 0) {
237 $out = ($realtype eq 'HASH') ? '{}' :
238 ($realtype eq 'ARRAY') ? '[]' :
240 push @post, $name . " = " . $s->{seen}{$id}[0];
243 $out = $s->{seen}{$id}[0];
244 if ($name =~ /^([\@\%])/) {
246 if ($out =~ /^\\$start/) {
247 $out = substr($out, 1);
250 $out = $start . '{' . $out . '}';
259 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
260 ($realtype eq 'CODE' and
261 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
267 if ($realpack and $realpack eq 'Regexp') {
273 # If purity is not set and maxdepth is set, then check depth:
274 # if we have reached maximum depth, return the string
275 # representation of the thing we are currently examining
276 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
278 and $s->{maxdepth} > 0
279 and $s->{level} >= $s->{maxdepth})
284 # we have a blessed ref
286 $out = $s->{'bless'} . '( ';
287 $blesspad = $s->{apad};
288 $s->{apad} .= ' ' if ($s->{indent} >= 2);
292 $ipad = $s->{xpad} x $s->{level};
294 if ($realtype eq 'SCALAR' || $realtype eq 'REF') {
296 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
299 $out .= '\\' . $s->_dump($$val, "\${$name}");
302 elsif ($realtype eq 'GLOB') {
303 $out .= '\\' . $s->_dump($$val, "*{$name}");
305 elsif ($realtype eq 'ARRAY') {
306 my($v, $pad, $mname);
308 $out .= ($name =~ /^\@/) ? '(' : '[';
309 $pad = $s->{sep} . $s->{pad} . $s->{apad};
310 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
311 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
312 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
313 ($mname = $name . '->');
314 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
316 $sname = $mname . '[' . $i . ']';
317 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
318 $out .= $pad . $ipad . $s->_dump($v, $sname);
319 $out .= "," if $i++ < $#$val;
321 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
322 $out .= ($name =~ /^\@/) ? ')' : ']';
324 elsif ($realtype eq 'HASH') {
325 my($k, $v, $pad, $lpad, $mname);
326 $out .= ($name =~ /^\%/) ? '(' : '{';
327 $pad = $s->{sep} . $s->{pad} . $s->{apad};
329 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
330 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
331 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
332 ($mname = $name . '->');
333 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
334 while (($k, $v) = each %$val) {
335 my $nk = $s->_dump($k, "");
336 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
337 $sname = $mname . '{' . $nk . '}';
338 $out .= $pad . $ipad . $nk . " => ";
340 # temporarily alter apad
341 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
342 $out .= $s->_dump($val->{$k}, $sname) . ",";
343 $s->{apad} = $lpad if $s->{indent} >= 2;
345 if (substr($out, -1) eq ',') {
347 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
349 $out .= ($name =~ /^\%/) ? ')' : '}';
351 elsif ($realtype eq 'CODE') {
352 $out .= 'sub { "DUMMY" }';
353 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
356 croak "Can\'t handle $realtype type.";
359 if ($realpack) { # we have a blessed ref
360 $out .= ', \'' . $realpack . '\'' . ' )';
361 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
362 $s->{apad} = $blesspad;
367 else { # simple scalar
370 # first, catalog the scalar
372 ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
373 if (exists $s->{seen}{$id}) {
374 if ($s->{seen}{$id}[2]) {
375 $out = $s->{seen}{$id}[0];
381 #warn "[>\\$name]\n";
382 $s->{seen}{$id} = ["\\$name", $ref];
385 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
386 my $name = substr($val, 1);
387 if ($name =~ /^[A-Za-z_][\w:]*$/) {
388 $name =~ s/^main::/::/;
392 $sname = $s->_dump($name, "");
393 $sname = '{' . $sname . '}';
397 local ($s->{level}) = 0;
398 for $k (qw(SCALAR ARRAY HASH)) {
399 my $gval = *$val{$k};
400 next unless defined $gval;
401 next if $k eq "SCALAR" && ! defined $$gval; # always there
403 # _dump can push into @post, so we hold our place using $postlen
404 my $postlen = scalar @post;
405 $post[$postlen] = "\*$sname = ";
406 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
407 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
410 $out .= '*' . $sname;
412 elsif (!defined($val)) {
415 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})$/) { # safe decimal number
420 $out .= qquote($val, $s->{useqq});
423 $val =~ s/([\\\'])/\\$1/g;
424 $out .= '\'' . $val . '\'';
429 # if we made it this far, $id was added to seen list at current
430 # level, so remove it to get deep copies
431 if ($s->{deepcopy}) {
432 delete($s->{seen}{$id});
435 $s->{seen}{$id}[2] = 1;
442 # non-OO style of earlier version
445 return Data::Dumper->Dump([@_]);
450 return Data::Dumper->Dumpxs([@_], []);
453 sub Dumpf { return Data::Dumper->Dump(@_) }
455 sub Dumpp { print Data::Dumper->Dump(@_) }
458 # reset the "seen" cache
487 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
492 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
497 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
502 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
507 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
512 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
517 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
522 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
527 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
532 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
537 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
541 # used by qquote below
552 # put a string value in double quotes
555 s/([\\\"\@\$])/\\$1/g;
556 return qq("$_") unless
557 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
559 my $high = shift || "";
560 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
562 if (ord('^')==94) { # ascii
563 # no need for 3 digits in escape for these
564 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
565 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
566 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
567 if ($high eq "iso8859") {
568 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
569 } elsif ($high eq "utf8") {
571 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
572 } elsif ($high eq "8bit") {
575 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
579 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
580 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
581 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
582 {'\\'.sprintf('%03o',ord($1))}eg;
593 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
599 # simple procedural interface
600 print Dumper($foo, $bar);
602 # extended usage with names
603 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
605 # configuration variables
607 local $Data::Dump::Purity = 1;
608 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
612 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
616 $d->Purity(1)->Terse(1)->Deepcopy(1);
622 Given a list of scalars or reference variables, writes out their contents in
623 perl syntax. The references can also be objects. The contents of each
624 variable is output in a single Perl statement. Handles self-referential
625 structures correctly.
627 The return value can be C<eval>ed to get back an identical copy of the
628 original reference structure.
630 Any references that are the same as one of those passed in will be named
631 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
632 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
633 notation. You can specify names for individual values to be dumped if you
634 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
635 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
638 The default output of self-referential structures can be C<eval>ed, but the
639 nested references to C<$VAR>I<n> will be undefined, since a recursive
640 structure cannot be constructed using one Perl statement. You should set the
641 C<Purity> flag to 1 to get additional statements that will correctly fill in
644 In the extended usage form, the references to be dumped can be given
645 user-specified names. If a name begins with a C<*>, the output will
646 describe the dereferenced type of the supplied reference for hashes and
647 arrays, and coderefs. Output of names will be avoided where possible if
648 the C<Terse> flag is set.
650 In many cases, methods that are used to set the internal state of the
651 object will return the object itself, so method calls can be conveniently
654 Several styles of output are possible, all controlled by setting
655 the C<Indent> flag. See L<Configuration Variables or Methods> below
663 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
665 Returns a newly created C<Data::Dumper> object. The first argument is an
666 anonymous array of values to be dumped. The optional second argument is an
667 anonymous array of names for the values. The names need not have a leading
668 C<$> sign, and must be comprised of alphanumeric characters. You can begin
669 a name with a C<*> to specify that the dereferenced type must be dumped
670 instead of the reference itself, for ARRAY and HASH references.
672 The prefix specified by C<$Data::Dumper::Varname> will be used with a
673 numeric suffix if the name for a value is undefined.
675 Data::Dumper will catalog all references encountered while dumping the
676 values. Cross-references (in the form of names of substructures in perl
677 syntax) will be inserted at all possible points, preserving any structural
678 interdependencies in the original set of values. Structure traversal is
679 depth-first, and proceeds in order from the first supplied value to
682 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
684 Returns the stringified form of the values stored in the object (preserving
685 the order in which they were supplied to C<new>), subject to the
686 configuration options below. In a list context, it returns a list
687 of strings corresponding to the supplied values.
689 The second form, for convenience, simply calls the C<new> method on its
690 arguments before dumping the object immediately.
692 =item I<$OBJ>->Seen(I<[HASHREF]>)
694 Queries or adds to the internal table of already encountered references.
695 You must use C<Reset> to explicitly clear the table if needed. Such
696 references are not dumped; instead, their names are inserted wherever they
697 are encountered subsequently. This is useful especially for properly
698 dumping subroutine references.
700 Expects a anonymous hash of name => value pairs. Same rules apply for names
701 as in C<new>. If no argument is supplied, will return the "seen" list of
702 name => value pairs, in a list context. Otherwise, returns the object
705 =item I<$OBJ>->Values(I<[ARRAYREF]>)
707 Queries or replaces the internal array of values that will be dumped.
708 When called without arguments, returns the values. Otherwise, returns the
711 =item I<$OBJ>->Names(I<[ARRAYREF]>)
713 Queries or replaces the internal array of user supplied names for the values
714 that will be dumped. When called without arguments, returns the names.
715 Otherwise, returns the object itself.
719 Clears the internal table of "seen" references and returns the object
728 =item Dumper(I<LIST>)
730 Returns the stringified form of the values in the list, subject to the
731 configuration options below. The values will be named C<$VAR>I<n> in the
732 output, where I<n> is a numeric suffix. Will return a list of strings
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. C<Dump()> will run slower if this flag is set,
791 since the fast XSUB implementation doesn't support it yet.
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 makes Dump() run slower, since the XSUB implementation
1025 does not support it.
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)