7 # Very old versions of warnings.pm load Carp. This can go wrong due
8 # to the circular dependency. If warnings is invoked before Carp,
9 # then warnings starts by loading Carp, then Carp (above) tries to
10 # invoke warnings, and gets nothing because warnings is in the process
11 # of loading and hasn't defined its import method yet. If we were
12 # only turning on warnings ("use warnings" above) this wouldn't be too
13 # bad, because Carp would just gets the state of the -w switch and so
14 # might not get some warnings that it wanted. The real problem is
15 # that we then want to turn off Unicode warnings, but "no warnings
16 # 'utf8'" won't be effective if we're in this circular-dependency
17 # situation. So, if warnings.pm is an affected version, we turn
18 # off all warnings ourselves by directly setting ${^WARNING_BITS}.
19 # On unaffected versions, we turn off just Unicode warnings, via
21 if(!defined($warnings::VERSION) || eval($warnings::VERSION) < 1.06) {
22 ${^WARNING_BITS} = "";
24 "warnings"->unimport("utf8");
28 sub _fetch_sub { # fetch sub without autovivifying
31 # only works with top-level packages
32 return unless exists($::{$pack});
34 return unless ref \$_ eq 'GLOB' && *$_{HASH} && exists $$_{$sub};
36 return ref \$_ eq 'GLOB' ? *$_{CODE} : undef
41 # UTF8_REGEXP_PROBLEM is a compile-time constant indicating whether Carp
42 # must avoid applying a regular expression to an upgraded (is_utf8)
43 # string. There are multiple problems, on different Perl versions,
44 # that require this to be avoided. All versions prior to 5.13.8 will
45 # load utf8_heavy.pl for the swash system, even if the regexp doesn't
46 # use character classes. Perl 5.6 and Perls [5.11.2, 5.13.11) exhibit
47 # specific problems when Carp is being invoked in the aftermath of a
51 *UTF8_REGEXP_PROBLEM = sub () { 1 };
53 *UTF8_REGEXP_PROBLEM = sub () { 0 };
57 # is_utf8() is essentially the utf8::is_utf8() function, which indicates
58 # whether a string is represented in the upgraded form (using UTF-8
59 # internally). As utf8::is_utf8() is only available from Perl 5.8
60 # onwards, extra effort is required here to make it work on Perl 5.6.
62 if(defined(my $sub = _fetch_sub utf8 => 'is_utf8')) {
65 # black magic for perl 5.6
66 *is_utf8 = sub { unpack("C", "\xaa".$_[0]) != 170 };
70 # The downgrade() function defined here is to be used for attempts to
71 # downgrade where it is acceptable to fail. It must be called with a
72 # second argument that is a true value.
74 if(defined(my $sub = _fetch_sub utf8 => 'downgrade')) {
75 *downgrade = \&{"utf8::downgrade"};
79 my $l = length($_[0]);
80 for(my $i = 0; $i != $l; $i++) {
81 my $o = ord(substr($_[0], $i, 1));
90 our $VERSION = '1.37_01';
96 our $MaxArgLen = 64; # How much of each argument to print. 0 = all.
97 our $MaxArgNums = 8; # How many arguments to print. 0 = all.
98 our $RefArgFormatter = undef; # allow caller to format reference arguments
101 our @ISA = ('Exporter');
102 our @EXPORT = qw(confess croak carp);
103 our @EXPORT_OK = qw(cluck verbose longmess shortmess);
104 our @EXPORT_FAIL = qw(verbose); # hook to enable verbose mode
106 # The members of %Internal are packages that are internal to perl.
107 # Carp will not report errors from within these packages if it
108 # can. The members of %CarpInternal are internal to Perl's warning
109 # system. Carp will not report errors from within these packages
110 # either, and will not report calls *to* these packages for carp and
111 # croak. They replace $CarpLevel, which is deprecated. The
112 # $Max(EvalLen|(Arg(Len|Nums)) variables are used to specify how the eval
113 # text and function arguments should be formatted when printed.
118 # disable these by default, so they can live w/o require Carp
119 $CarpInternal{Carp}++;
120 $CarpInternal{warnings}++;
121 $Internal{Exporter}++;
122 $Internal{'Exporter::Heavy'}++;
124 # if the caller specifies verbose usage ("perl -MCarp=verbose script.pl")
125 # then the following method will be called by the Exporter which knows
126 # to do this thanks to @EXPORT_FAIL, above. $_[1] will contain the word
129 sub export_fail { shift; $Verbose = shift if $_[0] eq 'verbose'; @_ }
133 return \&{"CORE::GLOBAL::caller"} if defined &{"CORE::GLOBAL::caller"};
139 # Icky backwards compatibility wrapper. :-(
141 # The story is that the original implementation hard-coded the
142 # number of call levels to go back, so calls to longmess were off
143 # by one. Other code began calling longmess and expecting this
144 # behaviour, so the replacement has to emulate that behaviour.
146 my $call_pack = $cgc ? $cgc->() : caller();
147 if ( $Internal{$call_pack} or $CarpInternal{$call_pack} ) {
148 return longmess_heavy(@_);
151 local $CarpLevel = $CarpLevel + 1;
152 return longmess_heavy(@_);
162 # Icky backwards compatibility wrapper. :-(
163 local @CARP_NOT = $cgc ? $cgc->() : caller();
167 sub croak { die shortmess @_ }
168 sub confess { die longmess @_ }
169 sub carp { warn shortmess @_ }
170 sub cluck { warn longmess @_ }
173 if("$]" >= 5.015002 || ("$]" >= 5.014002 && "$]" < 5.015) ||
174 ("$]" >= 5.012005 && "$]" < 5.013)) {
175 *CALLER_OVERRIDE_CHECK_OK = sub () { 1 };
177 *CALLER_OVERRIDE_CHECK_OK = sub () { 0 };
182 my $i = shift(@_) + 1;
186 # Some things override caller() but forget to implement the
187 # @DB::args part of it, which we need. We check for this by
188 # pre-populating @DB::args with a sentinel which no-one else
189 # has the address of, so that we can detect whether @DB::args
190 # has been properly populated. However, on earlier versions
191 # of perl this check tickles a bug in CORE::caller() which
192 # leaks memory. So we only check on fixed perls.
193 @DB::args = \$i if CALLER_OVERRIDE_CHECK_OK;
196 qw(pack file line sub has_args wantarray evaltext is_require) }
197 = $cgc ? $cgc->($i) : caller($i);
200 unless ( defined $call_info{file} ) {
204 my $sub_name = Carp::get_subname( \%call_info );
205 if ( $call_info{has_args} ) {
207 if (CALLER_OVERRIDE_CHECK_OK && @DB::args == 1
208 && ref $DB::args[0] eq ref \$i
209 && $DB::args[0] == \$i ) {
210 @DB::args = (); # Don't let anyone see the address of $i
213 my $func = $cgc or return '';
215 (_fetch_sub B => 'svref_2object' or return '')
217 my $package = $gv->STASH->NAME;
218 my $subname = $gv->NAME;
219 return unless defined $package && defined $subname;
221 # returning CORE::GLOBAL::caller isn't useful for tracing the cause:
222 return if $package eq 'CORE::GLOBAL' && $subname eq 'caller';
223 " in &${package}::$subname";
226 = "** Incomplete caller override detected$where; \@DB::args were not set **";
231 if ( $MaxArgNums and @args > $MaxArgNums )
232 { # More than we want to show?
233 $#args = $MaxArgNums - 1;
237 @args = map { Carp::format_arg($_) } @args;
244 # Push the args onto the subroutine
245 $sub_name .= '(' . join( ', ', @args ) . ')';
247 $call_info{sub_name} = $sub_name;
248 return wantarray() ? %call_info : \%call_info;
251 # Transform an argument to a function into a string.
257 # legitimate, let's not leak it.
261 local $in_recurse = 1;
262 local $SIG{__DIE__} = sub{};
263 eval {$arg->can('CARP_TRACE') }
266 return $arg->CARP_TRACE();
268 elsif (!$in_recurse &&
269 defined($RefArgFormatter) &&
272 local $in_recurse = 1;
273 local $SIG{__DIE__} = sub{};
274 eval {$arg = $RefArgFormatter->($arg); 1}
281 my $sub = _fetch_sub(overload => 'StrVal');
282 return $sub ? &$sub($arg) : "$arg";
285 return "undef" if !defined($arg);
287 return $arg if !(UTF8_REGEXP_PROBLEM && is_utf8($arg)) &&
288 $arg =~ /\A-?[0-9]+(?:\.[0-9]*)?(?:[eE][-+]?[0-9]+)?\z/;
290 if ( 2 < $MaxArgLen and $MaxArgLen < length($arg) ) {
291 substr ( $arg, $MaxArgLen - 3 ) = "";
294 if(UTF8_REGEXP_PROBLEM && is_utf8($arg)) {
295 for(my $i = length($arg); $i--; ) {
296 my $c = substr($arg, $i, 1);
297 my $x = substr($arg, 0, 0); # work around bug on Perl 5.8.{1,2}
298 if($c eq "\"" || $c eq "\\" || $c eq "\$" || $c eq "\@") {
299 substr $arg, $i, 0, "\\";
304 # This code is repeated in Regexp::CARP_TRACE()
305 if ($] ge 5.007_003) {
306 substr $arg, $i, 1, sprintf("\\x{%x}", $o)
307 if utf8::native_to_unicode($o) < utf8::native_to_unicode(0x20)
308 || utf8::native_to_unicode($o) > utf8::native_to_unicode(0x7e);
309 } elsif (ord("A") == 65) {
310 substr $arg, $i, 1, sprintf("\\x{%x}", $o)
311 if $o < 0x20 || $o > 0x7e;
312 } else { # Early EBCDIC
314 # 3 EBCDIC code pages supported then; all controls but one
315 # are the code points below SPACE. The other one is 0x5F on
316 # POSIX-BC; FF on the other two.
317 substr $arg, $i, 1, sprintf("\\x{%x}", $o)
318 if $o < ord(" ") || ((ord ("^") == 106)
324 $arg =~ s/([\"\\\$\@])/\\$1/g;
325 # This is all the ASCII printables spelled-out. It is portable to all
326 # Perl versions and platforms (such as EBCDIC). There are other more
327 # compact ways to do this, but may not work everywhere every version.
328 $arg =~ s/([^ !"\$\%#'()*+,\-.\/0123456789:;<=>?\@ABCDEFGHIJKLMNOPQRSTUVWXYZ\[\\\]^_`abcdefghijklmnopqrstuvwxyz\{|}~])/sprintf("\\x{%x}",ord($1))/eg;
331 return "\"".$arg."\"".$suffix;
334 sub Regexp::CARP_TRACE {
337 if(UTF8_REGEXP_PROBLEM && is_utf8($arg)) {
338 for(my $i = length($arg); $i--; ) {
339 my $o = ord(substr($arg, $i, 1));
340 my $x = substr($arg, 0, 0); # work around bug on Perl 5.8.{1,2}
342 # This code is repeated in format_arg()
343 if ($] ge 5.007_003) {
344 substr $arg, $i, 1, sprintf("\\x{%x}", $o)
345 if utf8::native_to_unicode($o) < utf8::native_to_unicode(0x20)
346 || utf8::native_to_unicode($o) > utf8::native_to_unicode(0x7e);
347 } elsif (ord("A") == 65) {
348 substr $arg, $i, 1, sprintf("\\x{%x}", $o)
349 if $o < 0x20 || $o > 0x7e;
350 } else { # Early EBCDIC
351 substr $arg, $i, 1, sprintf("\\x{%x}", $o)
352 if $o < ord(" ") || ((ord ("^") == 106)
358 # See comment in format_arg() about this same regex.
359 $arg =~ s/([^ !"\$\%#'()*+,\-.\/0123456789:;<=>?\@ABCDEFGHIJKLMNOPQRSTUVWXYZ\[\\\]^_`abcdefghijklmnopqrstuvwxyz\{|}~])/sprintf("\\x{%x}",ord($1))/eg;
363 if($arg =~ /\A\(\?\^?([a-z]*)(?:-[a-z]*)?:(.*)\)\z/s) {
364 ($suffix, $arg) = ($1, $2);
366 if ( 2 < $MaxArgLen and $MaxArgLen < length($arg) ) {
367 substr ( $arg, $MaxArgLen - 3 ) = "";
368 $suffix = "...".$suffix;
370 return "qr($arg)$suffix";
373 # Takes an inheritance cache and a package and returns
374 # an anon hash of known inheritances and anon array of
375 # inheritances which consequences have not been figured
380 $cache->{$pkg} ||= [ { $pkg => $pkg }, [ trusts_directly($pkg) ] ];
381 return @{ $cache->{$pkg} };
384 # Takes the info from caller() and figures out the name of
385 # the sub/require/eval
388 if ( defined( $info->{evaltext} ) ) {
389 my $eval = $info->{evaltext};
390 if ( $info->{is_require} ) {
391 return "require $eval";
394 $eval =~ s/([\\\'])/\\$1/g;
395 return "eval '" . str_len_trim( $eval, $MaxEvalLen ) . "'";
399 # this can happen on older perls when the sub (or the stash containing it)
401 if ( !defined( $info->{sub} ) ) {
402 return '__ANON__::__ANON__';
405 return ( $info->{sub} eq '(eval)' ) ? 'eval {...}' : $info->{sub};
408 # Figures out what call (from the point of view of the caller)
409 # the long error backtrace should start at.
412 my $lvl = $CarpLevel;
416 my @caller = $cgc ? $cgc->($i) : caller($i);
417 my $pkg = $caller[0];
418 unless ( defined($pkg) ) {
420 # This *shouldn't* happen.
423 $i = long_error_loc();
426 elsif (defined $caller[2]) {
427 # this can happen when the stash has been deleted
428 # in that case, just assume that it's a reasonable place to
429 # stop (the file and line data will still be intact in any
430 # case) - the only issue is that we can't detect if the
431 # deleted package was internal (so don't do that then)
433 redo unless 0 > --$lvl;
440 redo if $CarpInternal{$pkg};
441 redo unless 0 > --$lvl;
442 redo if $Internal{$pkg};
448 return @_ if ref( $_[0] ); # don't break references as exceptions
449 my $i = long_error_loc();
450 return ret_backtrace( $i, @_ );
453 # Returns a full stack backtrace starting from where it is
456 my ( $i, @error ) = @_;
458 my $err = join '', @error;
462 if ( defined &threads::tid ) {
463 my $tid = threads->tid;
464 $tid_msg = " thread $tid" if $tid;
467 my %i = caller_info($i);
468 $mess = "$err at $i{file} line $i{line}$tid_msg";
475 if($@ =~ /^Died at .*(, <.*?> line \d+).$/ ) {
481 while ( my %i = caller_info( ++$i ) ) {
482 $mess .= "\t$i{sub_name} called at $i{file} line $i{line}$tid_msg\n";
489 my ( $i, @error ) = @_;
490 my $err = join '', @error;
494 if ( defined &threads::tid ) {
495 my $tid = threads->tid;
496 $tid_msg = " thread $tid" if $tid;
499 my %i = caller_info($i);
500 return "$err at $i{file} line $i{line}$tid_msg\.\n";
503 sub short_error_loc {
504 # You have to create your (hash)ref out here, rather than defaulting it
505 # inside trusts *on a lexical*, as you want it to persist across calls.
506 # (You can default it on $_[2], but that gets messy)
509 my $lvl = $CarpLevel;
512 my $called = $cgc ? $cgc->($i) : caller($i);
514 my $caller = $cgc ? $cgc->($i) : caller($i);
516 if (!defined($caller)) {
517 my @caller = $cgc ? $cgc->($i) : caller($i);
519 # if there's no package but there is other caller info, then
520 # the package has been deleted - treat this as a valid package
522 redo if defined($called) && $CarpInternal{$called};
523 redo unless 0 > --$lvl;
530 redo if $Internal{$caller};
531 redo if $CarpInternal{$caller};
532 redo if $CarpInternal{$called};
533 redo if trusts( $called, $caller, $cache );
534 redo if trusts( $caller, $called, $cache );
535 redo unless 0 > --$lvl;
540 sub shortmess_heavy {
541 return longmess_heavy(@_) if $Verbose;
542 return @_ if ref( $_[0] ); # don't break references as exceptions
543 my $i = short_error_loc();
545 ret_summary( $i, @_ );
552 # If a string is too long, trims it with ...
555 my $max = shift || 0;
556 if ( 2 < $max and $max < length($str) ) {
557 substr( $str, $max - 3 ) = '...';
562 # Takes two packages and an optional cache. Says whether the
563 # first inherits from the second.
565 # Recursive versions of this have to work to avoid certain
566 # possible endless loops, and when following long chains of
567 # inheritance are less efficient.
572 my ( $known, $partial ) = get_status( $cache, $child );
574 # Figure out consequences until we have an answer
575 while ( @$partial and not exists $known->{$parent} ) {
576 my $anc = shift @$partial;
577 next if exists $known->{$anc};
579 my ( $anc_knows, $anc_partial ) = get_status( $cache, $anc );
580 my @found = keys %$anc_knows;
581 @$known{@found} = ();
582 push @$partial, @$anc_partial;
584 return exists $known->{$parent};
587 # Takes a package and gives a list of those trusted directly
588 sub trusts_directly {
591 my $stash = \%{"$class\::"};
592 for my $var (qw/ CARP_NOT ISA /) {
593 # Don't try using the variable until we know it exists,
594 # to avoid polluting the caller's namespace.
595 if ( $stash->{$var} && *{$stash->{$var}}{ARRAY} && @{$stash->{$var}} ) {
596 return @{$stash->{$var}}
602 if(!defined($warnings::VERSION) ||
603 do { no warnings "numeric"; $warnings::VERSION < 1.03 }) {
604 # Very old versions of warnings.pm import from Carp. This can go
605 # wrong due to the circular dependency. If Carp is invoked before
606 # warnings, then Carp starts by loading warnings, then warnings
607 # tries to import from Carp, and gets nothing because Carp is in
608 # the process of loading and hasn't defined its import method yet.
609 # So we work around that by manually exporting to warnings here.
611 *{"warnings::$_"} = \&$_ foreach @EXPORT;
620 Carp - alternative warn and die for modules
626 # warn user (from perspective of caller)
627 carp "string trimmed to 80 chars";
629 # die of errors (from perspective of caller)
630 croak "We're outta here!";
632 # die of errors with stack backtrace
633 confess "not implemented";
635 # cluck, longmess and shortmess not exported by default
636 use Carp qw(cluck longmess shortmess);
637 cluck "This is how we got here!";
638 $long_message = longmess( "message from cluck() or confess()" );
639 $short_message = shortmess( "message from carp() or croak()" );
643 The Carp routines are useful in your own modules because
644 they act like C<die()> or C<warn()>, but with a message which is more
645 likely to be useful to a user of your module. In the case of
646 C<cluck()> and C<confess()>, that context is a summary of every
647 call in the call-stack; C<longmess()> returns the contents of the error
650 For a shorter message you can use C<carp()> or C<croak()> which report the
651 error as being from where your module was called. C<shortmess()> returns the
652 contents of this error message. There is no guarantee that that is where the
653 error was, but it is a good educated guess.
655 C<Carp> takes care not to clobber the status variables C<$!> and C<$^E>
656 in the course of assembling its error messages. This means that a
657 C<$SIG{__DIE__}> or C<$SIG{__WARN__}> handler can capture the error
658 information held in those variables, if it is required to augment the
659 error message, and if the code calling C<Carp> left useful values there.
660 Of course, C<Carp> can't guarantee the latter.
662 You can also alter the way the output and logic of C<Carp> works, by
663 changing some global variables in the C<Carp> namespace. See the
664 section on C<GLOBAL VARIABLES> below.
666 Here is a more complete description of how C<carp> and C<croak> work.
667 What they do is search the call-stack for a function call stack where
668 they have not been told that there shouldn't be an error. If every
669 call is marked safe, they give up and give a full stack backtrace
670 instead. In other words they presume that the first likely looking
671 potential suspect is guilty. Their rules for telling whether
672 a call shouldn't generate errors work as follows:
678 Any call from a package to itself is safe.
682 Packages claim that there won't be errors on calls to or from
683 packages explicitly marked as safe by inclusion in C<@CARP_NOT>, or
684 (if that array is empty) C<@ISA>. The ability to override what
685 @ISA says is new in 5.8.
689 The trust in item 2 is transitive. If A trusts B, and B
690 trusts C, then A trusts C. So if you do not override C<@ISA>
691 with C<@CARP_NOT>, then this trust relationship is identical to,
696 Any call from an internal Perl module is safe. (Nothing keeps
697 user modules from marking themselves as internal to Perl, but
698 this practice is discouraged.)
702 Any call to Perl's warning system (eg Carp itself) is safe.
703 (This rule is what keeps it from reporting the error at the
704 point where you call C<carp> or C<croak>.)
708 C<$Carp::CarpLevel> can be set to skip a fixed number of additional
709 call levels. Using this is not recommended because it is very
710 difficult to get it to behave correctly.
714 =head2 Forcing a Stack Trace
716 As a debugging aid, you can force Carp to treat a croak as a confess
717 and a carp as a cluck across I<all> modules. In other words, force a
718 detailed stack trace to be given. This can be very helpful when trying
719 to understand why, or from where, a warning or error is being generated.
721 This feature is enabled by 'importing' the non-existent symbol
722 'verbose'. You would typically enable it by saying
724 perl -MCarp=verbose script.pl
726 or by including the string C<-MCarp=verbose> in the PERL5OPT
727 environment variable.
729 Alternately, you can set the global variable C<$Carp::Verbose> to true.
730 See the C<GLOBAL VARIABLES> section below.
732 =head2 Stack Trace formatting
734 At each stack level, the subroutine's name is displayed along with
735 its parameters. For simple scalars, this is sufficient. For complex
736 data types, such as objects and other references, this can simply
737 display C<'HASH(0x1ab36d8)'>.
739 Carp gives two ways to control this.
745 For objects, a method, C<CARP_TRACE>, will be called, if it exists. If
746 this method doesn't exist, or it recurses into C<Carp>, or it otherwise
747 throws an exception, this is skipped, and Carp moves on to the next option,
748 otherwise checking stops and the string returned is used. It is recommended
749 that the object's type is part of the string to make debugging easier.
753 For any type of reference, C<$Carp::RefArgFormatter> is checked (see below).
754 This variable is expected to be a code reference, and the current parameter
755 is passed in. If this function doesn't exist (the variable is undef), or
756 it recurses into C<Carp>, or it otherwise throws an exception, this is
757 skipped, and Carp moves on to the next option, otherwise checking stops
758 and the string returned is used.
762 Otherwise, if neither C<CARP_TRACE> nor C<$Carp::RefArgFormatter> is
763 available, stringify the value ignoring any overloading.
767 =head1 GLOBAL VARIABLES
769 =head2 $Carp::MaxEvalLen
771 This variable determines how many characters of a string-eval are to
772 be shown in the output. Use a value of C<0> to show all text.
776 =head2 $Carp::MaxArgLen
778 This variable determines how many characters of each argument to a
779 function to print. Use a value of C<0> to show the full length of the
784 =head2 $Carp::MaxArgNums
786 This variable determines how many arguments to each function to show.
787 Use a false value to show all arguments to a function call. To suppress all
788 arguments, use C<-1> or C<'0 but true'>.
792 =head2 $Carp::Verbose
794 This variable makes C<carp()> and C<croak()> generate stack backtraces
795 just like C<cluck()> and C<confess()>. This is how C<use Carp 'verbose'>
796 is implemented internally.
800 =head2 $Carp::RefArgFormatter
802 This variable sets a general argument formatter to display references.
803 Plain scalars and objects that implement C<CARP_TRACE> will not go through
804 this formatter. Calling C<Carp> from within this function is not supported.
806 local $Carp::RefArgFormatter = sub {
807 require Data::Dumper;
808 Data::Dumper::Dump($_[0]); # not necessarily safe
813 This variable, I<in your package>, says which packages are I<not> to be
814 considered as the location of an error. The C<carp()> and C<cluck()>
815 functions will skip over callers when reporting where an error occurred.
817 NB: This variable must be in the package's symbol table, thus:
820 our @CARP_NOT; # file scope
821 use vars qw(@CARP_NOT); # package scope
822 @My::Package::CARP_NOT = ... ; # explicit package variable
825 sub xyz { ... @CARP_NOT = ... } # w/o declarations above
826 my @CARP_NOT; # even at top-level
830 package My::Carping::Package;
833 sub bar { .... or _error('Wrong input') }
835 # temporary control of where'ness, __PACKAGE__ is implicit
836 local @CARP_NOT = qw(My::Friendly::Caller);
840 This would make C<Carp> report the error as coming from a caller not
841 in C<My::Carping::Package>, nor from C<My::Friendly::Caller>.
843 Also read the L</DESCRIPTION> section above, about how C<Carp> decides
844 where the error is reported from.
846 Use C<@CARP_NOT>, instead of C<$Carp::CarpLevel>.
848 Overrides C<Carp>'s use of C<@ISA>.
850 =head2 %Carp::Internal
852 This says what packages are internal to Perl. C<Carp> will never
853 report an error as being from a line in a package that is internal to
856 $Carp::Internal{ (__PACKAGE__) }++;
858 sub foo { ... or confess("whatever") };
860 would give a full stack backtrace starting from the first caller
861 outside of __PACKAGE__. (Unless that package was also internal to
864 =head2 %Carp::CarpInternal
866 This says which packages are internal to Perl's warning system. For
867 generating a full stack backtrace this is the same as being internal
868 to Perl, the stack backtrace will not start inside packages that are
869 listed in C<%Carp::CarpInternal>. But it is slightly different for
870 the summary message generated by C<carp> or C<croak>. There errors
871 will not be reported on any lines that are calling packages in
872 C<%Carp::CarpInternal>.
874 For example C<Carp> itself is listed in C<%Carp::CarpInternal>.
875 Therefore the full stack backtrace from C<confess> will not start
876 inside of C<Carp>, and the short message from calling C<croak> is
877 not placed on the line where C<croak> was called.
879 =head2 $Carp::CarpLevel
881 This variable determines how many additional call frames are to be
882 skipped that would not otherwise be when reporting where an error
883 occurred on a call to one of C<Carp>'s functions. It is fairly easy
884 to count these call frames on calls that generate a full stack
885 backtrace. However it is much harder to do this accounting for calls
886 that generate a short message. Usually people skip too many call
887 frames. If they are lucky they skip enough that C<Carp> goes all of
888 the way through the call stack, realizes that something is wrong, and
889 then generates a full stack backtrace. If they are unlucky then the
890 error is reported from somewhere misleading very high in the call
893 Therefore it is best to avoid C<$Carp::CarpLevel>. Instead use
894 C<@CARP_NOT>, C<%Carp::Internal> and C<%Carp::CarpInternal>.
900 The Carp routines don't handle exception objects currently.
901 If called with a first argument that is a reference, they simply
902 call die() or warn(), as appropriate.
911 The Carp module first appeared in Larry Wall's perl 5.000 distribution.
912 Since then it has been modified by several of the perl 5 porters.
913 Andrew Main (Zefram) <zefram@fysh.org> divested Carp into an independent
918 Copyright (C) 1994-2013 Larry Wall
920 Copyright (C) 2011, 2012, 2013 Andrew Main (Zefram) <zefram@fysh.org>
924 This module is free software; you can redistribute it and/or modify it
925 under the same terms as Perl itself.