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 $s->{level};
295 if ($realtype eq 'SCALAR') {
297 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
300 $out .= '\\' . $s->_dump($$val, "\${$name}");
303 elsif ($realtype eq 'GLOB') {
304 $out .= '\\' . $s->_dump($$val, "*{$name}");
306 elsif ($realtype eq 'ARRAY') {
307 my($v, $pad, $mname);
309 $out .= ($name =~ /^\@/) ? '(' : '[';
310 $pad = $s->{sep} . $s->{pad} . $s->{apad};
311 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
312 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
313 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
314 ($mname = $name . '->');
315 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
317 $sname = $mname . '[' . $i . ']';
318 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
319 $out .= $pad . $ipad . $s->_dump($v, $sname);
320 $out .= "," if $i++ < $#$val;
322 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
323 $out .= ($name =~ /^\@/) ? ')' : ']';
325 elsif ($realtype eq 'HASH') {
326 my($k, $v, $pad, $lpad, $mname);
327 $out .= ($name =~ /^\%/) ? '(' : '{';
328 $pad = $s->{sep} . $s->{pad} . $s->{apad};
330 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
331 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
332 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
333 ($mname = $name . '->');
334 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
335 while (($k, $v) = each %$val) {
336 my $nk = $s->_dump($k, "");
337 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
338 $sname = $mname . '{' . $nk . '}';
339 $out .= $pad . $ipad . $nk . " => ";
341 # temporarily alter apad
342 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
343 $out .= $s->_dump($val->{$k}, $sname) . ",";
344 $s->{apad} = $lpad if $s->{indent} >= 2;
346 if (substr($out, -1) eq ',') {
348 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
350 $out .= ($name =~ /^\%/) ? ')' : '}';
352 elsif ($realtype eq 'CODE') {
353 $out .= 'sub { "DUMMY" }';
354 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
357 croak "Can\'t handle $realtype type.";
360 if ($realpack) { # we have a blessed ref
361 $out .= ', \'' . $realpack . '\'' . ' )';
362 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
363 $s->{apad} = $blesspad;
368 else { # simple scalar
371 # first, catalog the scalar
373 ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
374 if (exists $s->{seen}{$id}) {
375 if ($s->{seen}{$id}[2]) {
376 $out = $s->{seen}{$id}[0];
382 #warn "[>\\$name]\n";
383 $s->{seen}{$id} = ["\\$name", $ref];
386 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
387 my $name = substr($val, 1);
388 if ($name =~ /^[A-Za-z_][\w:]*$/) {
389 $name =~ s/^main::/::/;
393 $sname = $s->_dump($name, "");
394 $sname = '{' . $sname . '}';
398 local ($s->{level}) = 0;
399 for $k (qw(SCALAR ARRAY HASH)) {
400 my $gval = *$val{$k};
401 next unless defined $gval;
402 next if $k eq "SCALAR" && ! defined $$gval; # always there
404 # _dump can push into @post, so we hold our place using $postlen
405 my $postlen = scalar @post;
406 $post[$postlen] = "\*$sname = ";
407 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
408 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
411 $out .= '*' . $sname;
413 elsif (!defined($val)) {
416 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})$/) { # safe decimal number
421 $out .= qquote($val, $s->{useqq});
424 $val =~ s/([\\\'])/\\$1/g;
425 $out .= '\'' . $val . '\'';
430 # if we made it this far, $id was added to seen list at current
431 # level, so remove it to get deep copies
432 if ($s->{deepcopy}) {
433 delete($s->{seen}{$id});
436 $s->{seen}{$id}[2] = 1;
443 # non-OO style of earlier version
446 return Data::Dumper->Dump([@_]);
451 return Data::Dumper->Dumpxs([@_], []);
454 sub Dumpf { return Data::Dumper->Dump(@_) }
456 sub Dumpp { print Data::Dumper->Dump(@_) }
459 # reset the "seen" cache
488 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
493 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
498 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
503 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
508 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
513 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
518 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
523 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
528 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
533 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
538 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
542 # used by qquote below
553 # put a string value in double quotes
556 s/([\\\"\@\$])/\\$1/g;
557 return qq("$_") unless
558 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
560 my $high = shift || "";
561 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
563 if (ord('^')==94) { # ascii
564 # no need for 3 digits in escape for these
565 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
566 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
567 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
568 if ($high eq "iso8859") {
569 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
570 } elsif ($high eq "utf8") {
572 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
573 } elsif ($high eq "8bit") {
576 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
580 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
581 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
582 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
583 {'\\'.sprintf('%03o',ord($1))}eg;
594 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
601 # simple procedural interface
602 print Dumper($foo, $bar);
604 # extended usage with names
605 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
607 # configuration variables
609 local $Data::Dump::Purity = 1;
610 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
614 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
618 $d->Purity(1)->Terse(1)->Deepcopy(1);
624 Given a list of scalars or reference variables, writes out their contents in
625 perl syntax. The references can also be objects. The contents of each
626 variable is output in a single Perl statement. Handles self-referential
627 structures correctly.
629 The return value can be C<eval>ed to get back an identical copy of the
630 original reference structure.
632 Any references that are the same as one of those passed in will be named
633 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
634 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
635 notation. You can specify names for individual values to be dumped if you
636 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
637 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
640 The default output of self-referential structures can be C<eval>ed, but the
641 nested references to C<$VAR>I<n> will be undefined, since a recursive
642 structure cannot be constructed using one Perl statement. You should set the
643 C<Purity> flag to 1 to get additional statements that will correctly fill in
646 In the extended usage form, the references to be dumped can be given
647 user-specified names. If a name begins with a C<*>, the output will
648 describe the dereferenced type of the supplied reference for hashes and
649 arrays, and coderefs. Output of names will be avoided where possible if
650 the C<Terse> flag is set.
652 In many cases, methods that are used to set the internal state of the
653 object will return the object itself, so method calls can be conveniently
656 Several styles of output are possible, all controlled by setting
657 the C<Indent> flag. See L<Configuration Variables or Methods> below
665 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
667 Returns a newly created C<Data::Dumper> object. The first argument is an
668 anonymous array of values to be dumped. The optional second argument is an
669 anonymous array of names for the values. The names need not have a leading
670 C<$> sign, and must be comprised of alphanumeric characters. You can begin
671 a name with a C<*> to specify that the dereferenced type must be dumped
672 instead of the reference itself, for ARRAY and HASH references.
674 The prefix specified by C<$Data::Dumper::Varname> will be used with a
675 numeric suffix if the name for a value is undefined.
677 Data::Dumper will catalog all references encountered while dumping the
678 values. Cross-references (in the form of names of substructures in perl
679 syntax) will be inserted at all possible points, preserving any structural
680 interdependencies in the original set of values. Structure traversal is
681 depth-first, and proceeds in order from the first supplied value to
684 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
686 Returns the stringified form of the values stored in the object (preserving
687 the order in which they were supplied to C<new>), subject to the
688 configuration options below. In an array context, it returns a list
689 of strings corresponding to the supplied values.
691 The second form, for convenience, simply calls the C<new> method on its
692 arguments before dumping the object immediately.
694 =item I<$OBJ>->Seen(I<[HASHREF]>)
696 Queries or adds to the internal table of already encountered references.
697 You must use C<Reset> to explicitly clear the table if needed. Such
698 references are not dumped; instead, their names are inserted wherever they
699 are encountered subsequently. This is useful especially for properly
700 dumping subroutine references.
702 Expects a anonymous hash of name => value pairs. Same rules apply for names
703 as in C<new>. If no argument is supplied, will return the "seen" list of
704 name => value pairs, in an array context. Otherwise, returns the object
707 =item I<$OBJ>->Values(I<[ARRAYREF]>)
709 Queries or replaces the internal array of values that will be dumped.
710 When called without arguments, returns the values. Otherwise, returns the
713 =item I<$OBJ>->Names(I<[ARRAYREF]>)
715 Queries or replaces the internal array of user supplied names for the values
716 that will be dumped. When called without arguments, returns the names.
717 Otherwise, returns the object itself.
721 Clears the internal table of "seen" references and returns the object
730 =item Dumper(I<LIST>)
732 Returns the stringified form of the values in the list, subject to the
733 configuration options below. The values will be named C<$VAR>I<n> in the
734 output, where I<n> is a numeric suffix. Will return a list of strings
739 =head2 Configuration Variables or Methods
741 Several configuration variables can be used to control the kind of output
742 generated when using the procedural interface. These variables are usually
743 C<local>ized in a block so that other parts of the code are not affected by
746 These variables determine the default state of the object created by calling
747 the C<new> method, but cannot be used to alter the state of the object
748 thereafter. The equivalent method names should be used instead to query
749 or set the internal state of the object.
751 The method forms return the object itself when called with arguments,
752 so that they can be chained together nicely.
756 =item $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
758 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
759 spews output without any newlines, indentation, or spaces between list
760 items. It is the most compact format possible that can still be called
761 valid perl. Style 1 outputs a readable form with newlines but no fancy
762 indentation (each level in the structure is simply indented by a fixed
763 amount of whitespace). Style 2 (the default) outputs a very readable form
764 which takes into account the length of hash keys (so the hash value lines
765 up). Style 3 is like style 2, but also annotates the elements of arrays
766 with their index (but the comment is on its own line, so array output
767 consumes twice the number of lines). Style 2 is the default.
769 =item $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
771 Controls the degree to which the output can be C<eval>ed to recreate the
772 supplied reference structures. Setting it to 1 will output additional perl
773 statements that will correctly recreate nested references. The default is
776 =item $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
778 Specifies the string that will be prefixed to every line of the output.
779 Empty string by default.
781 =item $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
783 Contains the prefix to use for tagging variable names in the output. The
786 =item $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
788 When set, enables the use of double quotes for representing string values.
789 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
790 characters will be backslashed, and unprintable characters will be output as
791 quoted octal integers. Since setting this variable imposes a performance
792 penalty, the default is 0. C<Dump()> will run slower if this flag is set,
793 since the fast XSUB implementation doesn't support it yet.
795 =item $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
797 When set, Data::Dumper will emit single, non-self-referential values as
798 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
799 will be avoided where possible, but be advised that such output may not
800 always be parseable by C<eval>.
802 =item $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
804 Can be set to a method name, or to an empty string to disable the feature.
805 Data::Dumper will invoke that method via the object before attempting to
806 stringify it. This method can alter the contents of the object (if, for
807 instance, it contains data allocated from C), and even rebless it in a
808 different package. The client is responsible for making sure the specified
809 method can be called via the object, and that the object ends up containing
810 only perl data types after the method has been called. Defaults to an empty
813 =item $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
815 Can be set to a method name, or to an empty string to disable the feature.
816 Data::Dumper will emit a method call for any objects that are to be dumped
817 using the syntax C<bless(DATA, CLASS)->METHOD()>. Note that this means that
818 the method specified will have to perform any modifications required on the
819 object (like creating new state within it, and/or reblessing it in a
820 different package) and then return it. The client is responsible for making
821 sure the method can be called via the object, and that it returns a valid
822 object. Defaults to an empty string.
824 =item $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
826 Can be set to a boolean value to enable deep copies of structures.
827 Cross-referencing will then only be done when absolutely essential
828 (i.e., to break reference cycles). Default is 0.
830 =item $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
832 Can be set to a boolean value to control whether hash keys are quoted.
833 A false value will avoid quoting hash keys when it looks like a simple
834 string. Default is 1, which will always enclose hash keys in quotes.
836 =item $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
838 Can be set to a string that specifies an alternative to the C<bless>
839 builtin operator used to create objects. A function with the specified
840 name should exist, and should accept the same arguments as the builtin.
843 =item $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
845 Can be set to a positive integer that specifies the depth beyond which
846 which we don't venture into a structure. Has no effect when
847 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
848 want to see more than enough). Default is 0, which means there is
863 Run these code snippets to get a quick feel for the behavior of this
864 module. When you are through with these examples, you may want to
865 add or change the various configuration variables described above,
866 to see their behavior. (See the testsuite in the Data::Dumper
867 distribution for more examples.)
873 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
875 package Fuz; # a weird REF-REF-SCALAR object
876 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
881 $boo = [ 1, [], "abcd", \*foo,
882 {1 => 'a', 023 => 'b', 0x45 => 'c'},
883 \\"p\q\'r", $foo, $fuz];
889 $bar = eval(Dumper($boo));
891 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
893 $Data::Dumper::Terse = 1; # don't output names where feasible
894 $Data::Dumper::Indent = 0; # turn off all pretty print
895 print Dumper($boo), "\n";
897 $Data::Dumper::Indent = 1; # mild pretty print
900 $Data::Dumper::Indent = 3; # pretty print with array indices
903 $Data::Dumper::Useqq = 1; # print strings in double quotes
908 # recursive structures
918 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
921 $Data::Dumper::Purity = 1; # fill in the holes for eval
922 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
923 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
926 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
927 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
930 $Data::Dumper::Purity = 0; # avoid cross-refs
931 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
943 print Data::Dumper->Dump([$f], [qw(f)]);
945 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
946 print Data::Dumper->Dump([$f], [qw(f)]);
950 # object-oriented usage
953 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
954 $d->Seen({'*c' => $c}); # stash a ref without printing it
957 $d->Reset->Purity(0); # empty the seen cache
958 print join "----\n", $d->Dump;
966 sub new { bless { state => 'awake' }, shift }
969 print STDERR "preparing to sleep\n";
970 $s->{state} = 'asleep';
971 return bless $s, 'Foo::ZZZ';
977 print STDERR "waking up\n";
978 $s->{state} = 'awake';
979 return bless $s, 'Foo';
985 $b = Data::Dumper->new([$a], ['c']);
986 $b->Freezer('Freeze');
991 print Data::Dumper->Dump([$d], ['d']);
995 # symbol substitution (useful for recreating CODE refs)
998 sub foo { print "foo speaking\n" }
1001 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1002 $d->Seen({ '*foo' => \&foo });
1008 Due to limitations of Perl subroutine call semantics, you cannot pass an
1009 array or hash. Prepend it with a C<\> to pass its reference instead. This
1010 will be remedied in time, with the arrival of prototypes in later versions
1011 of Perl. For now, you need to use the extended usage form, and prepend the
1012 name with a C<*> to output it as a hash or array.
1014 C<Data::Dumper> cheats with CODE references. If a code reference is
1015 encountered in the structure being processed, an anonymous subroutine that
1016 contains the string '"DUMMY"' will be inserted in its place, and a warning
1017 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1018 in mind that the anonymous sub that gets created is just a placeholder.
1019 Someday, perl will have a switch to cache-on-demand the string
1020 representation of a compiled piece of code, I hope. If you have prior
1021 knowledge of all the code refs that your data structures are likely
1022 to have, you can use the C<Seen> method to pre-seed the internal reference
1023 table and make the dumped output point to them, instead. See L<EXAMPLES>
1026 The C<Useqq> flag makes Dump() run slower, since the XSUB implementation
1027 does not support it.
1029 SCALAR objects have the weirdest looking C<bless> workaround.
1034 Gurusamy Sarathy gsar@activestate.com
1036 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1037 This program is free software; you can redistribute it and/or
1038 modify it under the same terms as Perl itself.
1043 Version 2.11 (unreleased)