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}};
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
554 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
556 my $high = shift || "";
557 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
559 if (ord('^')==94) { # ascii
560 # no need for 3 digits in escape for these
561 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
562 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
563 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
564 if ($high eq "iso8859") {
565 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
566 } elsif ($high eq "utf8") {
568 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
569 } elsif ($high eq "8bit") {
572 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
576 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
577 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
578 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
579 {'\\'.sprintf('%03o',ord($1))}eg;
590 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
597 # simple procedural interface
598 print Dumper($foo, $bar);
600 # extended usage with names
601 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
603 # configuration variables
605 local $Data::Dump::Purity = 1;
606 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
610 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
614 $d->Purity(1)->Terse(1)->Deepcopy(1);
620 Given a list of scalars or reference variables, writes out their contents in
621 perl syntax. The references can also be objects. The contents of each
622 variable is output in a single Perl statement. Handles self-referential
623 structures correctly.
625 The return value can be C<eval>ed to get back an identical copy of the
626 original reference structure.
628 Any references that are the same as one of those passed in will be named
629 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
630 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
631 notation. You can specify names for individual values to be dumped if you
632 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
633 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
636 The default output of self-referential structures can be C<eval>ed, but the
637 nested references to C<$VAR>I<n> will be undefined, since a recursive
638 structure cannot be constructed using one Perl statement. You should set the
639 C<Purity> flag to 1 to get additional statements that will correctly fill in
642 In the extended usage form, the references to be dumped can be given
643 user-specified names. If a name begins with a C<*>, the output will
644 describe the dereferenced type of the supplied reference for hashes and
645 arrays, and coderefs. Output of names will be avoided where possible if
646 the C<Terse> flag is set.
648 In many cases, methods that are used to set the internal state of the
649 object will return the object itself, so method calls can be conveniently
652 Several styles of output are possible, all controlled by setting
653 the C<Indent> flag. See L<Configuration Variables or Methods> below
661 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
663 Returns a newly created C<Data::Dumper> object. The first argument is an
664 anonymous array of values to be dumped. The optional second argument is an
665 anonymous array of names for the values. The names need not have a leading
666 C<$> sign, and must be comprised of alphanumeric characters. You can begin
667 a name with a C<*> to specify that the dereferenced type must be dumped
668 instead of the reference itself, for ARRAY and HASH references.
670 The prefix specified by C<$Data::Dumper::Varname> will be used with a
671 numeric suffix if the name for a value is undefined.
673 Data::Dumper will catalog all references encountered while dumping the
674 values. Cross-references (in the form of names of substructures in perl
675 syntax) will be inserted at all possible points, preserving any structural
676 interdependencies in the original set of values. Structure traversal is
677 depth-first, and proceeds in order from the first supplied value to
680 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
682 Returns the stringified form of the values stored in the object (preserving
683 the order in which they were supplied to C<new>), subject to the
684 configuration options below. In an array context, it returns a list
685 of strings corresponding to the supplied values.
687 The second form, for convenience, simply calls the C<new> method on its
688 arguments before dumping the object immediately.
690 =item I<$OBJ>->Dumpxs I<or> I<PACKAGE>->Dumpxs(I<ARRAYREF [>, I<ARRAYREF]>)
692 This method is available if you were able to compile and install the XSUB
693 extension to C<Data::Dumper>. It is exactly identical to the C<Dump> method
694 above, only about 4 to 5 times faster, since it is written entirely in C.
696 =item I<$OBJ>->Seen(I<[HASHREF]>)
698 Queries or adds to the internal table of already encountered references.
699 You must use C<Reset> to explicitly clear the table if needed. Such
700 references are not dumped; instead, their names are inserted wherever they
701 are encountered subsequently. This is useful especially for properly
702 dumping subroutine references.
704 Expects a anonymous hash of name => value pairs. Same rules apply for names
705 as in C<new>. If no argument is supplied, will return the "seen" list of
706 name => value pairs, in an array context. Otherwise, returns the object
709 =item I<$OBJ>->Values(I<[ARRAYREF]>)
711 Queries or replaces the internal array of values that will be dumped.
712 When called without arguments, returns the values. Otherwise, returns the
715 =item I<$OBJ>->Names(I<[ARRAYREF]>)
717 Queries or replaces the internal array of user supplied names for the values
718 that will be dumped. When called without arguments, returns the names.
719 Otherwise, returns the object itself.
723 Clears the internal table of "seen" references and returns the object
732 =item Dumper(I<LIST>)
734 Returns the stringified form of the values in the list, subject to the
735 configuration options below. The values will be named C<$VAR>I<n> in the
736 output, where I<n> is a numeric suffix. Will return a list of strings
739 =item DumperX(I<LIST>)
741 Identical to the C<Dumper()> function above, but this calls the XSUB
742 implementation. Only available if you were able to compile and install
743 the XSUB extensions in C<Data::Dumper>.
747 =head2 Configuration Variables or Methods
749 Several configuration variables can be used to control the kind of output
750 generated when using the procedural interface. These variables are usually
751 C<local>ized in a block so that other parts of the code are not affected by
754 These variables determine the default state of the object created by calling
755 the C<new> method, but cannot be used to alter the state of the object
756 thereafter. The equivalent method names should be used instead to query
757 or set the internal state of the object.
759 The method forms return the object itself when called with arguments,
760 so that they can be chained together nicely.
764 =item $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
766 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
767 spews output without any newlines, indentation, or spaces between list
768 items. It is the most compact format possible that can still be called
769 valid perl. Style 1 outputs a readable form with newlines but no fancy
770 indentation (each level in the structure is simply indented by a fixed
771 amount of whitespace). Style 2 (the default) outputs a very readable form
772 which takes into account the length of hash keys (so the hash value lines
773 up). Style 3 is like style 2, but also annotates the elements of arrays
774 with their index (but the comment is on its own line, so array output
775 consumes twice the number of lines). Style 2 is the default.
777 =item $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
779 Controls the degree to which the output can be C<eval>ed to recreate the
780 supplied reference structures. Setting it to 1 will output additional perl
781 statements that will correctly recreate nested references. The default is
784 =item $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
786 Specifies the string that will be prefixed to every line of the output.
787 Empty string by default.
789 =item $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
791 Contains the prefix to use for tagging variable names in the output. The
794 =item $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
796 When set, enables the use of double quotes for representing string values.
797 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
798 characters will be backslashed, and unprintable characters will be output as
799 quoted octal integers. Since setting this variable imposes a performance
800 penalty, the default is 0. The C<Dumpxs()> method does not honor this
803 =item $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
805 When set, Data::Dumper will emit single, non-self-referential values as
806 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
807 will be avoided where possible, but be advised that such output may not
808 always be parseable by C<eval>.
810 =item $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
812 Can be set to a method name, or to an empty string to disable the feature.
813 Data::Dumper will invoke that method via the object before attempting to
814 stringify it. This method can alter the contents of the object (if, for
815 instance, it contains data allocated from C), and even rebless it in a
816 different package. The client is responsible for making sure the specified
817 method can be called via the object, and that the object ends up containing
818 only perl data types after the method has been called. Defaults to an empty
821 =item $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
823 Can be set to a method name, or to an empty string to disable the feature.
824 Data::Dumper will emit a method call for any objects that are to be dumped
825 using the syntax C<bless(DATA, CLASS)->METHOD()>. Note that this means that
826 the method specified will have to perform any modifications required on the
827 object (like creating new state within it, and/or reblessing it in a
828 different package) and then return it. The client is responsible for making
829 sure the method can be called via the object, and that it returns a valid
830 object. Defaults to an empty string.
832 =item $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
834 Can be set to a boolean value to enable deep copies of structures.
835 Cross-referencing will then only be done when absolutely essential
836 (i.e., to break reference cycles). Default is 0.
838 =item $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
840 Can be set to a boolean value to control whether hash keys are quoted.
841 A false value will avoid quoting hash keys when it looks like a simple
842 string. Default is 1, which will always enclose hash keys in quotes.
844 =item $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
846 Can be set to a string that specifies an alternative to the C<bless>
847 builtin operator used to create objects. A function with the specified
848 name should exist, and should accept the same arguments as the builtin.
851 =item $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
853 Can be set to a positive integer that specifies the depth beyond which
854 which we don't venture into a structure. Has no effect when
855 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
856 want to see more than enough). Default is 0, which means there is
871 Run these code snippets to get a quick feel for the behavior of this
872 module. When you are through with these examples, you may want to
873 add or change the various configuration variables described above,
874 to see their behavior. (See the testsuite in the Data::Dumper
875 distribution for more examples.)
881 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
883 package Fuz; # a weird REF-REF-SCALAR object
884 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
889 $boo = [ 1, [], "abcd", \*foo,
890 {1 => 'a', 023 => 'b', 0x45 => 'c'},
891 \\"p\q\'r", $foo, $fuz];
897 $bar = eval(Dumper($boo));
899 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
901 $Data::Dumper::Terse = 1; # don't output names where feasible
902 $Data::Dumper::Indent = 0; # turn off all pretty print
903 print Dumper($boo), "\n";
905 $Data::Dumper::Indent = 1; # mild pretty print
908 $Data::Dumper::Indent = 3; # pretty print with array indices
911 $Data::Dumper::Useqq = 1; # print strings in double quotes
916 # recursive structures
926 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
929 $Data::Dumper::Purity = 1; # fill in the holes for eval
930 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
931 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
934 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
935 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
938 $Data::Dumper::Purity = 0; # avoid cross-refs
939 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
951 print Data::Dumper->Dump([$f], [qw(f)]);
953 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
954 print Data::Dumper->Dump([$f], [qw(f)]);
958 # object-oriented usage
961 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
962 $d->Seen({'*c' => $c}); # stash a ref without printing it
965 $d->Reset->Purity(0); # empty the seen cache
966 print join "----\n", $d->Dump;
974 sub new { bless { state => 'awake' }, shift }
977 print STDERR "preparing to sleep\n";
978 $s->{state} = 'asleep';
979 return bless $s, 'Foo::ZZZ';
985 print STDERR "waking up\n";
986 $s->{state} = 'awake';
987 return bless $s, 'Foo';
993 $b = Data::Dumper->new([$a], ['c']);
994 $b->Freezer('Freeze');
999 print Data::Dumper->Dump([$d], ['d']);
1003 # symbol substitution (useful for recreating CODE refs)
1006 sub foo { print "foo speaking\n" }
1009 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1010 $d->Seen({ '*foo' => \&foo });
1016 Due to limitations of Perl subroutine call semantics, you cannot pass an
1017 array or hash. Prepend it with a C<\> to pass its reference instead. This
1018 will be remedied in time, with the arrival of prototypes in later versions
1019 of Perl. For now, you need to use the extended usage form, and prepend the
1020 name with a C<*> to output it as a hash or array.
1022 C<Data::Dumper> cheats with CODE references. If a code reference is
1023 encountered in the structure being processed, an anonymous subroutine that
1024 contains the string '"DUMMY"' will be inserted in its place, and a warning
1025 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1026 in mind that the anonymous sub that gets created is just a placeholder.
1027 Someday, perl will have a switch to cache-on-demand the string
1028 representation of a compiled piece of code, I hope. If you have prior
1029 knowledge of all the code refs that your data structures are likely
1030 to have, you can use the C<Seen> method to pre-seed the internal reference
1031 table and make the dumped output point to them, instead. See L<EXAMPLES>
1034 The C<Useqq> flag is not honored by C<Dumpxs()> (it always outputs
1035 strings in single quotes).
1037 SCALAR objects have the weirdest looking C<bless> workaround.
1042 Gurusamy Sarathy gsar@activestate.com
1044 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1045 This program is free software; you can redistribute it and/or
1046 modify it under the same terms as Perl itself.
1051 Version 2.11 (unreleased)