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;
43 $Useperl = 0 unless defined $Useperl;
44 $Sortkeys = 0 unless defined $Sortkeys;
45 $Deparse = 0 unless defined $Deparse;
48 # expects an arrayref of values to be dumped.
49 # can optionally pass an arrayref of names for the values.
50 # names must have leading $ sign stripped. begin the name with *
51 # to cause output of arrays and hashes rather than refs.
56 croak "Usage: PACKAGE->new(ARRAYREF, [ARRAYREF])"
57 unless (defined($v) && (ref($v) eq 'ARRAY'));
58 $n = [] unless (defined($n) && (ref($v) eq 'ARRAY'));
61 level => 0, # current recursive depth
62 indent => $Indent, # various styles of indenting
63 pad => $Pad, # all lines prefixed by this string
64 xpad => "", # padding-per-level
65 apad => "", # added padding for hash keys n such
66 sep => "", # list separator
67 seen => {}, # local (nested) refs (id => [name, val])
68 todump => $v, # values to dump []
69 names => $n, # optional names for values []
70 varname => $Varname, # prefix to use for tagging nameless ones
71 purity => $Purity, # degree to which output is evalable
72 useqq => $Useqq, # use "" for strings (backslashitis ensues)
73 terse => $Terse, # avoid name output (where feasible)
74 freezer => $Freezer, # name of Freezer method for objects
75 toaster => $Toaster, # name of method to revive objects
76 deepcopy => $Deepcopy, # dont cross-ref, except to stop recursion
77 quotekeys => $Quotekeys, # quote hash keys
78 'bless' => $Bless, # keyword to use for "bless"
79 # expdepth => $Expdepth, # cutoff depth for explicit dumping
80 maxdepth => $Maxdepth, # depth beyond which we give up
81 useperl => $Useperl, # use the pure Perl implementation
82 sortkeys => $Sortkeys, # flag or filter for sorting hash keys
83 deparse => $Deparse, # use B::Deparse for coderefs
94 # add-to or query the table of already seen references
98 if (defined($g) && (ref($g) eq 'HASH')) {
100 while (($k, $v) = each %$g) {
101 if (defined $v and ref $v) {
102 ($id) = (overload::StrVal($v) =~ /\((.*)\)$/);
103 if ($k =~ /^[*](.*)$/) {
104 $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
105 (ref $v eq 'HASH') ? ( "\\\%" . $1 ) :
106 (ref $v eq 'CODE') ? ( "\\\&" . $1 ) :
109 elsif ($k !~ /^\$/) {
112 $s->{seen}{$id} = [$k, $v];
115 carp "Only refs supported, ignoring non-ref item \$$k";
121 return map { @$_ } values %{$s->{seen}};
126 # set or query the values to be dumped
130 if (defined($v) && (ref($v) eq 'ARRAY')) {
131 $s->{todump} = [@$v]; # make a copy
135 return @{$s->{todump}};
140 # set or query the names of the values to be dumped
144 if (defined($n) && (ref($n) eq 'ARRAY')) {
145 $s->{names} = [@$n]; # make a copy
149 return @{$s->{names}};
157 unless $Data::Dumper::Useperl || (ref($_[0]) && $_[0]->{useperl}) ||
158 $Data::Dumper::Useqq || (ref($_[0]) && $_[0]->{useqq}) ||
159 $Data::Dumper::Deparse || (ref($_[0]) && $_[0]->{deparse});
164 # dump the refs in the current dumper object.
165 # expects same args as new() if called via package name.
169 my(@out, $val, $name);
173 $s = $s->new(@_) unless ref $s;
175 for $val (@{$s->{todump}}) {
178 $name = $s->{names}[$i++];
180 if ($name =~ /^[*](.*)$/) {
182 $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
183 (ref $val eq 'HASH') ? ( "\%" . $1 ) :
184 (ref $val eq 'CODE') ? ( "\*" . $1 ) :
191 elsif ($name !~ /^\$/) {
192 $name = "\$" . $name;
196 $name = "\$" . $s->{varname} . $i;
201 local($s->{apad}) = $s->{apad};
202 $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
203 $valstr = $s->_dump($val, $name);
206 $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
207 $out .= $s->{pad} . $valstr . $s->{sep};
208 $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
209 . ';' . $s->{sep} if @post;
213 return wantarray ? @out : join('', @out);
217 # twist, toil and turn;
218 # and recurse, of course.
219 # sometimes sordidly;
220 # and curse if no recourse.
223 my($s, $val, $name) = @_;
225 my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
232 # prep it, if it looks like an object
233 if (my $freezer = $s->{freezer}) {
234 $val->$freezer() if UNIVERSAL::can($val, $freezer);
237 ($realpack, $realtype, $id) =
238 (overload::StrVal($val) =~ /^(?:(.*)\=)?([^=]*)\(([^\(]*)\)$/);
240 # if it has a name, we need to either look it up, or keep a tab
241 # on it so we know when we hit it later
242 if (defined($name) and length($name)) {
243 # keep a tab on it so that we dont fall into recursive pit
244 if (exists $s->{seen}{$id}) {
245 # if ($s->{expdepth} < $s->{level}) {
246 if ($s->{purity} and $s->{level} > 0) {
247 $out = ($realtype eq 'HASH') ? '{}' :
248 ($realtype eq 'ARRAY') ? '[]' :
250 push @post, $name . " = " . $s->{seen}{$id}[0];
253 $out = $s->{seen}{$id}[0];
254 if ($name =~ /^([\@\%])/) {
256 if ($out =~ /^\\$start/) {
257 $out = substr($out, 1);
260 $out = $start . '{' . $out . '}';
269 $s->{seen}{$id} = [ (($name =~ /^[@%]/) ? ('\\' . $name ) :
270 ($realtype eq 'CODE' and
271 $name =~ /^[*](.*)$/) ? ('\\&' . $1 ) :
277 if ($realpack and $realpack eq 'Regexp') {
283 # If purity is not set and maxdepth is set, then check depth:
284 # if we have reached maximum depth, return the string
285 # representation of the thing we are currently examining
286 # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
288 and $s->{maxdepth} > 0
289 and $s->{level} >= $s->{maxdepth})
294 # we have a blessed ref
296 $out = $s->{'bless'} . '( ';
297 $blesspad = $s->{apad};
298 $s->{apad} .= ' ' if ($s->{indent} >= 2);
302 $ipad = $s->{xpad} x $s->{level};
304 if ($realtype eq 'SCALAR' || $realtype eq 'REF') {
306 $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
309 $out .= '\\' . $s->_dump($$val, "\${$name}");
312 elsif ($realtype eq 'GLOB') {
313 $out .= '\\' . $s->_dump($$val, "*{$name}");
315 elsif ($realtype eq 'ARRAY') {
316 my($v, $pad, $mname);
318 $out .= ($name =~ /^\@/) ? '(' : '[';
319 $pad = $s->{sep} . $s->{pad} . $s->{apad};
320 ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
321 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
322 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
323 ($mname = $name . '->');
324 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
326 $sname = $mname . '[' . $i . ']';
327 $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
328 $out .= $pad . $ipad . $s->_dump($v, $sname);
329 $out .= "," if $i++ < $#$val;
331 $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
332 $out .= ($name =~ /^\@/) ? ')' : ']';
334 elsif ($realtype eq 'HASH') {
335 my($k, $v, $pad, $lpad, $mname);
336 $out .= ($name =~ /^\%/) ? '(' : '{';
337 $pad = $s->{sep} . $s->{pad} . $s->{apad};
339 ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
340 # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
341 ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
342 ($mname = $name . '->');
343 $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
344 my ($sortkeys, $keys, $key) = ("$s->{sortkeys}");
346 if (ref($s->{sortkeys}) eq 'CODE') {
347 $keys = $s->{sortkeys}($val);
348 unless (ref($keys) eq 'ARRAY') {
349 carp "Sortkeys subroutine did not return ARRAYREF";
354 $keys = [ sort keys %$val ];
357 while (($k, $v) = ! $sortkeys ? (each %$val) :
358 @$keys ? ($key = shift(@$keys), $val->{$key}) :
361 my $nk = $s->_dump($k, "");
362 $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
363 $sname = $mname . '{' . $nk . '}';
364 $out .= $pad . $ipad . $nk . " => ";
366 # temporarily alter apad
367 $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
368 $out .= $s->_dump($val->{$k}, $sname) . ",";
369 $s->{apad} = $lpad if $s->{indent} >= 2;
371 if (substr($out, -1) eq ',') {
373 $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
375 $out .= ($name =~ /^\%/) ? ')' : '}';
377 elsif ($realtype eq 'CODE') {
380 my $sub = 'sub ' . (B::Deparse->new)->coderef2text($val);
381 $pad = $s->{sep} . $s->{pad} . $s->{xpad} . $s->{apad} . ' ';
382 $sub =~ s/\n/$pad/gse;
385 $out .= 'sub { "DUMMY" }';
386 carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
390 croak "Can\'t handle $realtype type.";
393 if ($realpack) { # we have a blessed ref
394 $out .= ', \'' . $realpack . '\'' . ' )';
395 $out .= '->' . $s->{toaster} . '()' if $s->{toaster} ne '';
396 $s->{apad} = $blesspad;
401 else { # simple scalar
404 # first, catalog the scalar
406 ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
407 if (exists $s->{seen}{$id}) {
408 if ($s->{seen}{$id}[2]) {
409 $out = $s->{seen}{$id}[0];
415 #warn "[>\\$name]\n";
416 $s->{seen}{$id} = ["\\$name", $ref];
419 if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) { # glob
420 my $name = substr($val, 1);
421 if ($name =~ /^[A-Za-z_][\w:]*$/) {
422 $name =~ s/^main::/::/;
426 $sname = $s->_dump($name, "");
427 $sname = '{' . $sname . '}';
431 local ($s->{level}) = 0;
432 for $k (qw(SCALAR ARRAY HASH)) {
433 my $gval = *$val{$k};
434 next unless defined $gval;
435 next if $k eq "SCALAR" && ! defined $$gval; # always there
437 # _dump can push into @post, so we hold our place using $postlen
438 my $postlen = scalar @post;
439 $post[$postlen] = "\*$sname = ";
440 local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
441 $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
444 $out .= '*' . $sname;
446 elsif (!defined($val)) {
449 elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})\z/) { # safe decimal number
453 if ($s->{useqq} or $val =~ tr/\0-\377//c) {
454 # Fall back to qq if there's unicode
455 $out .= qquote($val, $s->{useqq});
458 $val =~ s/([\\\'])/\\$1/g;
459 $out .= '\'' . $val . '\'';
464 # if we made it this far, $id was added to seen list at current
465 # level, so remove it to get deep copies
466 if ($s->{deepcopy}) {
467 delete($s->{seen}{$id});
470 $s->{seen}{$id}[2] = 1;
477 # non-OO style of earlier version
480 return Data::Dumper->Dump([@_]);
485 return Data::Dumper->Dumpxs([@_], []);
488 sub Dumpf { return Data::Dumper->Dump(@_) }
490 sub Dumpp { print Data::Dumper->Dump(@_) }
493 # reset the "seen" cache
522 defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
527 defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
532 defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
537 defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
542 defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
547 defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
552 defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
557 defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
562 defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
567 defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
572 defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
577 defined($v) ? (($s->{'useperl'} = $v), return $s) : $s->{'useperl'};
582 defined($v) ? (($s->{'sortkeys'} = $v), return $s) : $s->{'sortkeys'};
587 defined($v) ? (($s->{'deparse'} = $v), return $s) : $s->{'deparse'};
590 # used by qquote below
601 # put a string value in double quotes
604 s/([\\\"\@\$])/\\$1/g;
605 my $bytes; { use bytes; $bytes = length }
606 s/([^\x00-\x7f])/'\x{'.sprintf("%x",ord($1)).'}'/ge if $bytes > length;
607 return qq("$_") unless
608 /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/; # fast exit
610 my $high = shift || "";
611 s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
613 if (ord('^')==94) { # ascii
614 # no need for 3 digits in escape for these
615 s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
616 s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
617 # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
618 if ($high eq "iso8859") {
619 s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
620 } elsif ($high eq "utf8") {
622 # $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
623 } elsif ($high eq "8bit") {
626 s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
627 s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
631 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
632 {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
633 s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
634 {'\\'.sprintf('%03o',ord($1))}eg;
645 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
651 # simple procedural interface
652 print Dumper($foo, $bar);
654 # extended usage with names
655 print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
657 # configuration variables
659 local $Data::Dump::Purity = 1;
660 eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
664 $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
668 $d->Purity(1)->Terse(1)->Deepcopy(1);
674 Given a list of scalars or reference variables, writes out their contents in
675 perl syntax. The references can also be objects. The contents of each
676 variable is output in a single Perl statement. Handles self-referential
677 structures correctly.
679 The return value can be C<eval>ed to get back an identical copy of the
680 original reference structure.
682 Any references that are the same as one of those passed in will be named
683 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
684 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
685 notation. You can specify names for individual values to be dumped if you
686 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
687 something else. See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
690 The default output of self-referential structures can be C<eval>ed, but the
691 nested references to C<$VAR>I<n> will be undefined, since a recursive
692 structure cannot be constructed using one Perl statement. You should set the
693 C<Purity> flag to 1 to get additional statements that will correctly fill in
696 In the extended usage form, the references to be dumped can be given
697 user-specified names. If a name begins with a C<*>, the output will
698 describe the dereferenced type of the supplied reference for hashes and
699 arrays, and coderefs. Output of names will be avoided where possible if
700 the C<Terse> flag is set.
702 In many cases, methods that are used to set the internal state of the
703 object will return the object itself, so method calls can be conveniently
706 Several styles of output are possible, all controlled by setting
707 the C<Indent> flag. See L<Configuration Variables or Methods> below
715 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
717 Returns a newly created C<Data::Dumper> object. The first argument is an
718 anonymous array of values to be dumped. The optional second argument is an
719 anonymous array of names for the values. The names need not have a leading
720 C<$> sign, and must be comprised of alphanumeric characters. You can begin
721 a name with a C<*> to specify that the dereferenced type must be dumped
722 instead of the reference itself, for ARRAY and HASH references.
724 The prefix specified by C<$Data::Dumper::Varname> will be used with a
725 numeric suffix if the name for a value is undefined.
727 Data::Dumper will catalog all references encountered while dumping the
728 values. Cross-references (in the form of names of substructures in perl
729 syntax) will be inserted at all possible points, preserving any structural
730 interdependencies in the original set of values. Structure traversal is
731 depth-first, and proceeds in order from the first supplied value to
734 =item I<$OBJ>->Dump I<or> I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
736 Returns the stringified form of the values stored in the object (preserving
737 the order in which they were supplied to C<new>), subject to the
738 configuration options below. In a list context, it returns a list
739 of strings corresponding to the supplied values.
741 The second form, for convenience, simply calls the C<new> method on its
742 arguments before dumping the object immediately.
744 =item I<$OBJ>->Seen(I<[HASHREF]>)
746 Queries or adds to the internal table of already encountered references.
747 You must use C<Reset> to explicitly clear the table if needed. Such
748 references are not dumped; instead, their names are inserted wherever they
749 are encountered subsequently. This is useful especially for properly
750 dumping subroutine references.
752 Expects an anonymous hash of name => value pairs. Same rules apply for names
753 as in C<new>. If no argument is supplied, will return the "seen" list of
754 name => value pairs, in a list context. Otherwise, returns the object
757 =item I<$OBJ>->Values(I<[ARRAYREF]>)
759 Queries or replaces the internal array of values that will be dumped.
760 When called without arguments, returns the values. Otherwise, returns the
763 =item I<$OBJ>->Names(I<[ARRAYREF]>)
765 Queries or replaces the internal array of user supplied names for the values
766 that will be dumped. When called without arguments, returns the names.
767 Otherwise, returns the object itself.
771 Clears the internal table of "seen" references and returns the object
780 =item Dumper(I<LIST>)
782 Returns the stringified form of the values in the list, subject to the
783 configuration options below. The values will be named C<$VAR>I<n> in the
784 output, where I<n> is a numeric suffix. Will return a list of strings
789 =head2 Configuration Variables or Methods
791 Several configuration variables can be used to control the kind of output
792 generated when using the procedural interface. These variables are usually
793 C<local>ized in a block so that other parts of the code are not affected by
796 These variables determine the default state of the object created by calling
797 the C<new> method, but cannot be used to alter the state of the object
798 thereafter. The equivalent method names should be used instead to query
799 or set the internal state of the object.
801 The method forms return the object itself when called with arguments,
802 so that they can be chained together nicely.
806 =item $Data::Dumper::Indent I<or> I<$OBJ>->Indent(I<[NEWVAL]>)
808 Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
809 spews output without any newlines, indentation, or spaces between list
810 items. It is the most compact format possible that can still be called
811 valid perl. Style 1 outputs a readable form with newlines but no fancy
812 indentation (each level in the structure is simply indented by a fixed
813 amount of whitespace). Style 2 (the default) outputs a very readable form
814 which takes into account the length of hash keys (so the hash value lines
815 up). Style 3 is like style 2, but also annotates the elements of arrays
816 with their index (but the comment is on its own line, so array output
817 consumes twice the number of lines). Style 2 is the default.
819 =item $Data::Dumper::Purity I<or> I<$OBJ>->Purity(I<[NEWVAL]>)
821 Controls the degree to which the output can be C<eval>ed to recreate the
822 supplied reference structures. Setting it to 1 will output additional perl
823 statements that will correctly recreate nested references. The default is
826 =item $Data::Dumper::Pad I<or> I<$OBJ>->Pad(I<[NEWVAL]>)
828 Specifies the string that will be prefixed to every line of the output.
829 Empty string by default.
831 =item $Data::Dumper::Varname I<or> I<$OBJ>->Varname(I<[NEWVAL]>)
833 Contains the prefix to use for tagging variable names in the output. The
836 =item $Data::Dumper::Useqq I<or> I<$OBJ>->Useqq(I<[NEWVAL]>)
838 When set, enables the use of double quotes for representing string values.
839 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
840 characters will be backslashed, and unprintable characters will be output as
841 quoted octal integers. Since setting this variable imposes a performance
842 penalty, the default is 0. C<Dump()> will run slower if this flag is set,
843 since the fast XSUB implementation doesn't support it yet.
845 =item $Data::Dumper::Terse I<or> I<$OBJ>->Terse(I<[NEWVAL]>)
847 When set, Data::Dumper will emit single, non-self-referential values as
848 atoms/terms rather than statements. This means that the C<$VAR>I<n> names
849 will be avoided where possible, but be advised that such output may not
850 always be parseable by C<eval>.
852 =item $Data::Dumper::Freezer I<or> $I<OBJ>->Freezer(I<[NEWVAL]>)
854 Can be set to a method name, or to an empty string to disable the feature.
855 Data::Dumper will invoke that method via the object before attempting to
856 stringify it. This method can alter the contents of the object (if, for
857 instance, it contains data allocated from C), and even rebless it in a
858 different package. The client is responsible for making sure the specified
859 method can be called via the object, and that the object ends up containing
860 only perl data types after the method has been called. Defaults to an empty
863 =item $Data::Dumper::Toaster I<or> $I<OBJ>->Toaster(I<[NEWVAL]>)
865 Can be set to a method name, or to an empty string to disable the feature.
866 Data::Dumper will emit a method call for any objects that are to be dumped
867 using the syntax C<bless(DATA, CLASS)-E<gt>METHOD()>. Note that this means that
868 the method specified will have to perform any modifications required on the
869 object (like creating new state within it, and/or reblessing it in a
870 different package) and then return it. The client is responsible for making
871 sure the method can be called via the object, and that it returns a valid
872 object. Defaults to an empty string.
874 =item $Data::Dumper::Deepcopy I<or> $I<OBJ>->Deepcopy(I<[NEWVAL]>)
876 Can be set to a boolean value to enable deep copies of structures.
877 Cross-referencing will then only be done when absolutely essential
878 (i.e., to break reference cycles). Default is 0.
880 =item $Data::Dumper::Quotekeys I<or> $I<OBJ>->Quotekeys(I<[NEWVAL]>)
882 Can be set to a boolean value to control whether hash keys are quoted.
883 A false value will avoid quoting hash keys when it looks like a simple
884 string. Default is 1, which will always enclose hash keys in quotes.
886 =item $Data::Dumper::Bless I<or> $I<OBJ>->Bless(I<[NEWVAL]>)
888 Can be set to a string that specifies an alternative to the C<bless>
889 builtin operator used to create objects. A function with the specified
890 name should exist, and should accept the same arguments as the builtin.
893 =item $Data::Dumper::Maxdepth I<or> $I<OBJ>->Maxdepth(I<[NEWVAL]>)
895 Can be set to a positive integer that specifies the depth beyond which
896 which we don't venture into a structure. Has no effect when
897 C<Data::Dumper::Purity> is set. (Useful in debugger when we often don't
898 want to see more than enough). Default is 0, which means there is
901 =item $Data::Dumper::Useperl I<or> $I<OBJ>->Useperl(I<[NEWVAL]>)
903 Can be set to a boolean value which controls whether the pure Perl
904 implementation of C<Data::Dumper> is used. The C<Data::Dumper> module is
905 a dual implementation, with almost all functionality written in both
906 pure Perl and also in XS ('C'). Since the XS version is much faster, it
907 will always be used if possible. This option lets you override the
908 default behavior, usually for testing purposes only. Default is 0, which
909 means the XS implementation will be used if possible.
911 =item $Data::Dumper::Sortkeys I<or> $I<OBJ>->Sortkeys(I<[NEWVAL]>)
913 Can be set to a boolean value to control whether hash keys are dumped in
914 sorted order. A true value will cause the keys of all hashes to be
915 dumped in Perl's default sort order. Can also be set to a subroutine
916 reference which will be called for each hash that is dumped. In this
917 case C<Data::Dumper> will call the subroutine once for each hash,
918 passing it the reference of the hash. The purpose of the subroutine is
919 to return a reference to an array of the keys that will be dumped, in
920 the order that they should be dumped. Using this feature, you can
921 control both the order of the keys, and which keys are actually used. In
922 other words, this subroutine acts as a filter by which you can exclude
923 certain keys from being dumped. Default is 0, which means that hash keys
926 =item $Data::Dumper::Deparse I<or> $I<OBJ>->Deparse(I<[NEWVAL]>)
928 Can be set to a boolean value to control whether code references are
929 turned into perl source code. If set to a true value, C<B::Deparse>
930 will be used to get the source of the code reference. Using this option
931 will force using the Perl implementation of the dumper, since the fast
932 XSUB implementation doesn't support it.
934 Caution : use this option only if you know that your coderefs will be
935 properly reconstructed by C<B::Deparse>.
949 Run these code snippets to get a quick feel for the behavior of this
950 module. When you are through with these examples, you may want to
951 add or change the various configuration variables described above,
952 to see their behavior. (See the testsuite in the Data::Dumper
953 distribution for more examples.)
959 sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
961 package Fuz; # a weird REF-REF-SCALAR object
962 sub new {bless \($_ = \ 'fu\'z'), $_[0]};
967 $boo = [ 1, [], "abcd", \*foo,
968 {1 => 'a', 023 => 'b', 0x45 => 'c'},
969 \\"p\q\'r", $foo, $fuz];
975 $bar = eval(Dumper($boo));
977 print Dumper($boo), Dumper($bar); # pretty print (no array indices)
979 $Data::Dumper::Terse = 1; # don't output names where feasible
980 $Data::Dumper::Indent = 0; # turn off all pretty print
981 print Dumper($boo), "\n";
983 $Data::Dumper::Indent = 1; # mild pretty print
986 $Data::Dumper::Indent = 3; # pretty print with array indices
989 $Data::Dumper::Useqq = 1; # print strings in double quotes
994 # recursive structures
1004 print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
1007 $Data::Dumper::Purity = 1; # fill in the holes for eval
1008 print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
1009 print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
1012 $Data::Dumper::Deepcopy = 1; # avoid cross-refs
1013 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1016 $Data::Dumper::Purity = 0; # avoid cross-refs
1017 print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
1029 print Data::Dumper->Dump([$f], [qw(f)]);
1031 $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down
1032 print Data::Dumper->Dump([$f], [qw(f)]);
1036 # object-oriented usage
1039 $d = Data::Dumper->new([$a,$b], [qw(a b)]);
1040 $d->Seen({'*c' => $c}); # stash a ref without printing it
1043 $d->Reset->Purity(0); # empty the seen cache
1044 print join "----\n", $d->Dump;
1052 sub new { bless { state => 'awake' }, shift }
1055 print STDERR "preparing to sleep\n";
1056 $s->{state} = 'asleep';
1057 return bless $s, 'Foo::ZZZ';
1063 print STDERR "waking up\n";
1064 $s->{state} = 'awake';
1065 return bless $s, 'Foo';
1071 $b = Data::Dumper->new([$a], ['c']);
1072 $b->Freezer('Freeze');
1073 $b->Toaster('Thaw');
1077 print Data::Dumper->Dump([$d], ['d']);
1081 # symbol substitution (useful for recreating CODE refs)
1084 sub foo { print "foo speaking\n" }
1087 $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1088 $d->Seen({ '*foo' => \&foo });
1093 # sorting and filtering hash keys
1096 $Data::Dumper::Sortkeys = \&my_filter;
1097 my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' };
1098 my $bar = { %$foo };
1099 my $baz = { reverse %$foo };
1100 print Dumper [ $foo, $bar, $baz ];
1104 # return an array ref containing the hash keys to dump
1105 # in the order that you want them to be dumped
1107 # Sort the keys of %$foo in reverse numeric order
1108 $hash eq $foo ? (sort {$b <=> $a} keys %$hash) :
1109 # Only dump the odd number keys of %$bar
1110 $hash eq $bar ? (grep {$_ % 2} keys %$hash) :
1111 # Sort keys in default order for all other hashes
1118 Due to limitations of Perl subroutine call semantics, you cannot pass an
1119 array or hash. Prepend it with a C<\> to pass its reference instead. This
1120 will be remedied in time, now that Perl has subroutine prototypes.
1121 For now, you need to use the extended usage form, and prepend the
1122 name with a C<*> to output it as a hash or array.
1124 C<Data::Dumper> cheats with CODE references. If a code reference is
1125 encountered in the structure being processed (and if you haven't set
1126 the C<Deparse> flag), an anonymous subroutine that
1127 contains the string '"DUMMY"' will be inserted in its place, and a warning
1128 will be printed if C<Purity> is set. You can C<eval> the result, but bear
1129 in mind that the anonymous sub that gets created is just a placeholder.
1130 Someday, perl will have a switch to cache-on-demand the string
1131 representation of a compiled piece of code, I hope. If you have prior
1132 knowledge of all the code refs that your data structures are likely
1133 to have, you can use the C<Seen> method to pre-seed the internal reference
1134 table and make the dumped output point to them, instead. See L<EXAMPLES>
1137 The C<Useqq> and C<Deparse> flags makes Dump() run slower, since the
1138 XSUB implementation does not support them.
1140 SCALAR objects have the weirdest looking C<bless> workaround.
1145 Gurusamy Sarathy gsar@activestate.com
1147 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1148 This program is free software; you can redistribute it and/or
1149 modify it under the same terms as Perl itself.
1154 Version 2.12 (unreleased)