Commit | Line | Data |
---|---|---|
a0d0e21e | 1 | package Carp; |
8c3d9721 | 2 | |
18c097a2 | 3 | our $VERSION = '1.15'; |
b75c8c73 | 4 | |
8c3d9721 DM |
5 | our $MaxEvalLen = 0; |
6 | our $Verbose = 0; | |
7 | our $CarpLevel = 0; | |
8 | our $MaxArgLen = 64; # How much of each argument to print. 0 = all. | |
9 | our $MaxArgNums = 8; # How many arguments to print. 0 = all. | |
748a9306 | 10 | |
a0d0e21e | 11 | require Exporter; |
8c3d9721 DM |
12 | our @ISA = ('Exporter'); |
13 | our @EXPORT = qw(confess croak carp); | |
14 | our @EXPORT_OK = qw(cluck verbose longmess shortmess); | |
15 | our @EXPORT_FAIL = qw(verbose); # hook to enable verbose mode | |
af80c6a7 | 16 | |
ba7a4549 RGS |
17 | # The members of %Internal are packages that are internal to perl. |
18 | # Carp will not report errors from within these packages if it | |
19 | # can. The members of %CarpInternal are internal to Perl's warning | |
20 | # system. Carp will not report errors from within these packages | |
21 | # either, and will not report calls *to* these packages for carp and | |
22 | # croak. They replace $CarpLevel, which is deprecated. The | |
23 | # $Max(EvalLen|(Arg(Len|Nums)) variables are used to specify how the eval | |
24 | # text and function arguments should be formatted when printed. | |
25 | ||
26 | # disable these by default, so they can live w/o require Carp | |
27 | $CarpInternal{Carp}++; | |
28 | $CarpInternal{warnings}++; | |
29 | $Internal{Exporter}++; | |
30 | $Internal{'Exporter::Heavy'}++; | |
31 | ||
af80c6a7 JH |
32 | # if the caller specifies verbose usage ("perl -MCarp=verbose script.pl") |
33 | # then the following method will be called by the Exporter which knows | |
34 | # to do this thanks to @EXPORT_FAIL, above. $_[1] will contain the word | |
35 | # 'verbose'. | |
36 | ||
29ddba3b | 37 | sub export_fail { shift; $Verbose = shift if $_[0] eq 'verbose'; @_ } |
7b8d334a | 38 | |
ba7a4549 RGS |
39 | sub longmess { |
40 | # Icky backwards compatibility wrapper. :-( | |
41 | # | |
42 | # The story is that the original implementation hard-coded the | |
43 | # number of call levels to go back, so calls to longmess were off | |
44 | # by one. Other code began calling longmess and expecting this | |
45 | # behaviour, so the replacement has to emulate that behaviour. | |
a894cef1 | 46 | my $call_pack = defined &{"CORE::GLOBAL::caller"} ? &{"CORE::GLOBAL::caller"}() : caller(); |
ba7a4549 RGS |
47 | if ($Internal{$call_pack} or $CarpInternal{$call_pack}) { |
48 | return longmess_heavy(@_); | |
49 | } | |
50 | else { | |
51 | local $CarpLevel = $CarpLevel + 1; | |
52 | return longmess_heavy(@_); | |
53 | } | |
54 | }; | |
55 | ||
56 | sub shortmess { | |
57 | # Icky backwards compatibility wrapper. :-( | |
a894cef1 | 58 | local @CARP_NOT = defined &{"CORE::GLOBAL::caller"} ? &{"CORE::GLOBAL::caller"}() : caller(); |
ba7a4549 RGS |
59 | shortmess_heavy(@_); |
60 | }; | |
7b8d334a GS |
61 | |
62 | sub croak { die shortmess @_ } | |
63 | sub confess { die longmess @_ } | |
64 | sub carp { warn shortmess @_ } | |
65 | sub cluck { warn longmess @_ } | |
a0d0e21e | 66 | |
ba7a4549 RGS |
67 | sub caller_info { |
68 | my $i = shift(@_) + 1; | |
69 | package DB; | |
70 | my %call_info; | |
71 | @call_info{ | |
72 | qw(pack file line sub has_args wantarray evaltext is_require) | |
a894cef1 | 73 | } = defined &{"CORE::GLOBAL::caller"} ? &{"CORE::GLOBAL::caller"}($i) : caller($i); |
ba7a4549 RGS |
74 | |
75 | unless (defined $call_info{pack}) { | |
76 | return (); | |
77 | } | |
78 | ||
79 | my $sub_name = Carp::get_subname(\%call_info); | |
80 | if ($call_info{has_args}) { | |
81 | my @args = map {Carp::format_arg($_)} @DB::args; | |
82 | if ($MaxArgNums and @args > $MaxArgNums) { # More than we want to show? | |
83 | $#args = $MaxArgNums; | |
84 | push @args, '...'; | |
85 | } | |
86 | # Push the args onto the subroutine | |
87 | $sub_name .= '(' . join (', ', @args) . ')'; | |
88 | } | |
89 | $call_info{sub_name} = $sub_name; | |
90 | return wantarray() ? %call_info : \%call_info; | |
91 | } | |
92 | ||
93 | # Transform an argument to a function into a string. | |
94 | sub format_arg { | |
95 | my $arg = shift; | |
96 | if (ref($arg)) { | |
97 | $arg = defined($overload::VERSION) ? overload::StrVal($arg) : "$arg"; | |
98 | } | |
99 | if (defined($arg)) { | |
100 | $arg =~ s/'/\\'/g; | |
101 | $arg = str_len_trim($arg, $MaxArgLen); | |
102 | ||
103 | # Quote it? | |
104 | $arg = "'$arg'" unless $arg =~ /^-?[\d.]+\z/; | |
105 | } else { | |
106 | $arg = 'undef'; | |
107 | } | |
108 | ||
109 | # The following handling of "control chars" is direct from | |
110 | # the original code - it is broken on Unicode though. | |
111 | # Suggestions? | |
112 | utf8::is_utf8($arg) | |
113 | or $arg =~ s/([[:cntrl:]]|[[:^ascii:]])/sprintf("\\x{%x}",ord($1))/eg; | |
114 | return $arg; | |
115 | } | |
116 | ||
117 | # Takes an inheritance cache and a package and returns | |
118 | # an anon hash of known inheritances and anon array of | |
119 | # inheritances which consequences have not been figured | |
120 | # for. | |
121 | sub get_status { | |
122 | my $cache = shift; | |
123 | my $pkg = shift; | |
124 | $cache->{$pkg} ||= [{$pkg => $pkg}, [trusts_directly($pkg)]]; | |
125 | return @{$cache->{$pkg}}; | |
126 | } | |
127 | ||
128 | # Takes the info from caller() and figures out the name of | |
129 | # the sub/require/eval | |
130 | sub get_subname { | |
131 | my $info = shift; | |
132 | if (defined($info->{evaltext})) { | |
133 | my $eval = $info->{evaltext}; | |
134 | if ($info->{is_require}) { | |
135 | return "require $eval"; | |
136 | } | |
137 | else { | |
138 | $eval =~ s/([\\\'])/\\$1/g; | |
139 | return "eval '" . str_len_trim($eval, $MaxEvalLen) . "'"; | |
140 | } | |
141 | } | |
142 | ||
143 | return ($info->{sub} eq '(eval)') ? 'eval {...}' : $info->{sub}; | |
144 | } | |
145 | ||
146 | # Figures out what call (from the point of view of the caller) | |
147 | # the long error backtrace should start at. | |
148 | sub long_error_loc { | |
149 | my $i; | |
150 | my $lvl = $CarpLevel; | |
151 | { | |
45a2d978 | 152 | ++$i; |
a894cef1 | 153 | my $pkg = defined &{"CORE::GLOBAL::caller"} ? &{"CORE::GLOBAL::caller"}($i) : caller($i); |
ba7a4549 RGS |
154 | unless(defined($pkg)) { |
155 | # This *shouldn't* happen. | |
156 | if (%Internal) { | |
157 | local %Internal; | |
158 | $i = long_error_loc(); | |
159 | last; | |
160 | } | |
161 | else { | |
162 | # OK, now I am irritated. | |
163 | return 2; | |
164 | } | |
165 | } | |
166 | redo if $CarpInternal{$pkg}; | |
167 | redo unless 0 > --$lvl; | |
168 | redo if $Internal{$pkg}; | |
169 | } | |
170 | return $i - 1; | |
171 | } | |
172 | ||
173 | ||
174 | sub longmess_heavy { | |
175 | return @_ if ref($_[0]); # don't break references as exceptions | |
176 | my $i = long_error_loc(); | |
177 | return ret_backtrace($i, @_); | |
178 | } | |
179 | ||
180 | # Returns a full stack backtrace starting from where it is | |
181 | # told. | |
182 | sub ret_backtrace { | |
183 | my ($i, @error) = @_; | |
184 | my $mess; | |
185 | my $err = join '', @error; | |
186 | $i++; | |
187 | ||
188 | my $tid_msg = ''; | |
189 | if (defined &threads::tid) { | |
190 | my $tid = threads->tid; | |
191 | $tid_msg = " thread $tid" if $tid; | |
192 | } | |
193 | ||
194 | my %i = caller_info($i); | |
195 | $mess = "$err at $i{file} line $i{line}$tid_msg\n"; | |
196 | ||
197 | while (my %i = caller_info(++$i)) { | |
198 | $mess .= "\t$i{sub_name} called at $i{file} line $i{line}$tid_msg\n"; | |
199 | } | |
200 | ||
201 | return $mess; | |
202 | } | |
203 | ||
204 | sub ret_summary { | |
205 | my ($i, @error) = @_; | |
206 | my $err = join '', @error; | |
207 | $i++; | |
208 | ||
209 | my $tid_msg = ''; | |
210 | if (defined &threads::tid) { | |
211 | my $tid = threads->tid; | |
212 | $tid_msg = " thread $tid" if $tid; | |
213 | } | |
214 | ||
215 | my %i = caller_info($i); | |
216 | return "$err at $i{file} line $i{line}$tid_msg\n"; | |
217 | } | |
218 | ||
219 | ||
220 | sub short_error_loc { | |
221 | # You have to create your (hash)ref out here, rather than defaulting it | |
222 | # inside trusts *on a lexical*, as you want it to persist across calls. | |
223 | # (You can default it on $_[2], but that gets messy) | |
224 | my $cache = {}; | |
225 | my $i = 1; | |
226 | my $lvl = $CarpLevel; | |
227 | { | |
45a2d978 | 228 | |
a894cef1 | 229 | my $called = defined &{"CORE::GLOBAL::caller"} ? &{"CORE::GLOBAL::caller"}($i) : caller($i); |
45a2d978 | 230 | $i++; |
a894cef1 | 231 | my $caller = defined &{"CORE::GLOBAL::caller"} ? &{"CORE::GLOBAL::caller"}($i) : caller($i); |
ba7a4549 RGS |
232 | |
233 | return 0 unless defined($caller); # What happened? | |
234 | redo if $Internal{$caller}; | |
235 | redo if $CarpInternal{$caller}; | |
236 | redo if $CarpInternal{$called}; | |
237 | redo if trusts($called, $caller, $cache); | |
238 | redo if trusts($caller, $called, $cache); | |
239 | redo unless 0 > --$lvl; | |
240 | } | |
241 | return $i - 1; | |
242 | } | |
243 | ||
244 | ||
245 | sub shortmess_heavy { | |
246 | return longmess_heavy(@_) if $Verbose; | |
247 | return @_ if ref($_[0]); # don't break references as exceptions | |
248 | my $i = short_error_loc(); | |
249 | if ($i) { | |
250 | ret_summary($i, @_); | |
251 | } | |
252 | else { | |
253 | longmess_heavy(@_); | |
254 | } | |
255 | } | |
256 | ||
257 | # If a string is too long, trims it with ... | |
258 | sub str_len_trim { | |
259 | my $str = shift; | |
260 | my $max = shift || 0; | |
261 | if (2 < $max and $max < length($str)) { | |
262 | substr($str, $max - 3) = '...'; | |
263 | } | |
264 | return $str; | |
265 | } | |
266 | ||
267 | # Takes two packages and an optional cache. Says whether the | |
268 | # first inherits from the second. | |
269 | # | |
270 | # Recursive versions of this have to work to avoid certain | |
271 | # possible endless loops, and when following long chains of | |
272 | # inheritance are less efficient. | |
273 | sub trusts { | |
274 | my $child = shift; | |
275 | my $parent = shift; | |
276 | my $cache = shift; | |
277 | my ($known, $partial) = get_status($cache, $child); | |
278 | # Figure out consequences until we have an answer | |
279 | while (@$partial and not exists $known->{$parent}) { | |
280 | my $anc = shift @$partial; | |
281 | next if exists $known->{$anc}; | |
282 | $known->{$anc}++; | |
283 | my ($anc_knows, $anc_partial) = get_status($cache, $anc); | |
284 | my @found = keys %$anc_knows; | |
285 | @$known{@found} = (); | |
286 | push @$partial, @$anc_partial; | |
287 | } | |
288 | return exists $known->{$parent}; | |
289 | } | |
290 | ||
291 | # Takes a package and gives a list of those trusted directly | |
292 | sub trusts_directly { | |
293 | my $class = shift; | |
294 | no strict 'refs'; | |
295 | no warnings 'once'; | |
296 | return @{"$class\::CARP_NOT"} | |
297 | ? @{"$class\::CARP_NOT"} | |
298 | : @{"$class\::ISA"}; | |
299 | } | |
300 | ||
748a9306 | 301 | 1; |
ba7a4549 | 302 | |
0cda2667 DM |
303 | __END__ |
304 | ||
305 | =head1 NAME | |
306 | ||
307 | carp - warn of errors (from perspective of caller) | |
308 | ||
309 | cluck - warn of errors with stack backtrace | |
310 | (not exported by default) | |
311 | ||
312 | croak - die of errors (from perspective of caller) | |
313 | ||
314 | confess - die of errors with stack backtrace | |
315 | ||
0cda2667 DM |
316 | =head1 SYNOPSIS |
317 | ||
318 | use Carp; | |
319 | croak "We're outta here!"; | |
320 | ||
321 | use Carp qw(cluck); | |
322 | cluck "This is how we got here!"; | |
323 | ||
0cda2667 DM |
324 | =head1 DESCRIPTION |
325 | ||
326 | The Carp routines are useful in your own modules because | |
327 | they act like die() or warn(), but with a message which is more | |
328 | likely to be useful to a user of your module. In the case of | |
329 | cluck, confess, and longmess that context is a summary of every | |
d735c2ef BT |
330 | call in the call-stack. For a shorter message you can use C<carp> |
331 | or C<croak> which report the error as being from where your module | |
332 | was called. There is no guarantee that that is where the error | |
333 | was, but it is a good educated guess. | |
0cda2667 DM |
334 | |
335 | You can also alter the way the output and logic of C<Carp> works, by | |
336 | changing some global variables in the C<Carp> namespace. See the | |
337 | section on C<GLOBAL VARIABLES> below. | |
338 | ||
3b46207f | 339 | Here is a more complete description of how C<carp> and C<croak> work. |
d735c2ef BT |
340 | What they do is search the call-stack for a function call stack where |
341 | they have not been told that there shouldn't be an error. If every | |
342 | call is marked safe, they give up and give a full stack backtrace | |
343 | instead. In other words they presume that the first likely looking | |
344 | potential suspect is guilty. Their rules for telling whether | |
0cda2667 DM |
345 | a call shouldn't generate errors work as follows: |
346 | ||
347 | =over 4 | |
348 | ||
349 | =item 1. | |
350 | ||
351 | Any call from a package to itself is safe. | |
352 | ||
353 | =item 2. | |
354 | ||
355 | Packages claim that there won't be errors on calls to or from | |
d735c2ef BT |
356 | packages explicitly marked as safe by inclusion in C<@CARP_NOT>, or |
357 | (if that array is empty) C<@ISA>. The ability to override what | |
0cda2667 DM |
358 | @ISA says is new in 5.8. |
359 | ||
360 | =item 3. | |
361 | ||
362 | The trust in item 2 is transitive. If A trusts B, and B | |
d735c2ef BT |
363 | trusts C, then A trusts C. So if you do not override C<@ISA> |
364 | with C<@CARP_NOT>, then this trust relationship is identical to, | |
0cda2667 DM |
365 | "inherits from". |
366 | ||
367 | =item 4. | |
368 | ||
369 | Any call from an internal Perl module is safe. (Nothing keeps | |
370 | user modules from marking themselves as internal to Perl, but | |
371 | this practice is discouraged.) | |
372 | ||
373 | =item 5. | |
374 | ||
d735c2ef BT |
375 | Any call to Perl's warning system (eg Carp itself) is safe. |
376 | (This rule is what keeps it from reporting the error at the | |
377 | point where you call C<carp> or C<croak>.) | |
378 | ||
379 | =item 6. | |
380 | ||
381 | C<$Carp::CarpLevel> can be set to skip a fixed number of additional | |
382 | call levels. Using this is not recommended because it is very | |
383 | difficult to get it to behave correctly. | |
0cda2667 DM |
384 | |
385 | =back | |
386 | ||
387 | =head2 Forcing a Stack Trace | |
388 | ||
389 | As a debugging aid, you can force Carp to treat a croak as a confess | |
390 | and a carp as a cluck across I<all> modules. In other words, force a | |
391 | detailed stack trace to be given. This can be very helpful when trying | |
392 | to understand why, or from where, a warning or error is being generated. | |
393 | ||
394 | This feature is enabled by 'importing' the non-existent symbol | |
395 | 'verbose'. You would typically enable it by saying | |
396 | ||
397 | perl -MCarp=verbose script.pl | |
398 | ||
11ed4d01 | 399 | or by including the string C<-MCarp=verbose> in the PERL5OPT |
0cda2667 DM |
400 | environment variable. |
401 | ||
402 | Alternately, you can set the global variable C<$Carp::Verbose> to true. | |
403 | See the C<GLOBAL VARIABLES> section below. | |
404 | ||
405 | =head1 GLOBAL VARIABLES | |
406 | ||
0cda2667 DM |
407 | =head2 $Carp::MaxEvalLen |
408 | ||
409 | This variable determines how many characters of a string-eval are to | |
410 | be shown in the output. Use a value of C<0> to show all text. | |
411 | ||
412 | Defaults to C<0>. | |
413 | ||
414 | =head2 $Carp::MaxArgLen | |
415 | ||
416 | This variable determines how many characters of each argument to a | |
417 | function to print. Use a value of C<0> to show the full length of the | |
418 | argument. | |
419 | ||
420 | Defaults to C<64>. | |
421 | ||
422 | =head2 $Carp::MaxArgNums | |
423 | ||
424 | This variable determines how many arguments to each function to show. | |
425 | Use a value of C<0> to show all arguments to a function call. | |
426 | ||
427 | Defaults to C<8>. | |
428 | ||
429 | =head2 $Carp::Verbose | |
430 | ||
d735c2ef BT |
431 | This variable makes C<carp> and C<cluck> generate stack backtraces |
432 | just like C<cluck> and C<confess>. This is how C<use Carp 'verbose'> | |
433 | is implemented internally. | |
434 | ||
435 | Defaults to C<0>. | |
436 | ||
b60d6605 AG |
437 | =head2 @CARP_NOT |
438 | ||
439 | This variable, I<in your package>, says which packages are I<not> to be | |
440 | considered as the location of an error. The C<carp()> and C<cluck()> | |
441 | functions will skip over callers when reporting where an error occurred. | |
442 | ||
443 | NB: This variable must be in the package's symbol table, thus: | |
444 | ||
445 | # These work | |
446 | our @CARP_NOT; # file scope | |
447 | use vars qw(@CARP_NOT); # package scope | |
448 | @My::Package::CARP_NOT = ... ; # explicit package variable | |
449 | ||
450 | # These don't work | |
451 | sub xyz { ... @CARP_NOT = ... } # w/o declarations above | |
452 | my @CARP_NOT; # even at top-level | |
453 | ||
454 | Example of use: | |
455 | ||
456 | package My::Carping::Package; | |
457 | use Carp; | |
458 | our @CARP_NOT; | |
459 | sub bar { .... or _error('Wrong input') } | |
460 | sub _error { | |
461 | # temporary control of where'ness, __PACKAGE__ is implicit | |
462 | local @CARP_NOT = qw(My::Friendly::Caller); | |
463 | carp(@_) | |
464 | } | |
465 | ||
466 | This would make C<Carp> report the error as coming from a caller not | |
467 | in C<My::Carping::Package>, nor from C<My::Friendly::Caller>. | |
468 | ||
345e2394 | 469 | Also read the L</DESCRIPTION> section above, about how C<Carp> decides |
b60d6605 AG |
470 | where the error is reported from. |
471 | ||
472 | Use C<@CARP_NOT>, instead of C<$Carp::CarpLevel>. | |
473 | ||
474 | Overrides C<Carp>'s use of C<@ISA>. | |
475 | ||
d735c2ef BT |
476 | =head2 %Carp::Internal |
477 | ||
478 | This says what packages are internal to Perl. C<Carp> will never | |
479 | report an error as being from a line in a package that is internal to | |
480 | Perl. For example: | |
481 | ||
2a6a7022 | 482 | $Carp::Internal{ (__PACKAGE__) }++; |
d735c2ef BT |
483 | # time passes... |
484 | sub foo { ... or confess("whatever") }; | |
485 | ||
486 | would give a full stack backtrace starting from the first caller | |
487 | outside of __PACKAGE__. (Unless that package was also internal to | |
488 | Perl.) | |
489 | ||
490 | =head2 %Carp::CarpInternal | |
491 | ||
492 | This says which packages are internal to Perl's warning system. For | |
493 | generating a full stack backtrace this is the same as being internal | |
494 | to Perl, the stack backtrace will not start inside packages that are | |
495 | listed in C<%Carp::CarpInternal>. But it is slightly different for | |
496 | the summary message generated by C<carp> or C<croak>. There errors | |
497 | will not be reported on any lines that are calling packages in | |
498 | C<%Carp::CarpInternal>. | |
499 | ||
500 | For example C<Carp> itself is listed in C<%Carp::CarpInternal>. | |
501 | Therefore the full stack backtrace from C<confess> will not start | |
502 | inside of C<Carp>, and the short message from calling C<croak> is | |
503 | not placed on the line where C<croak> was called. | |
504 | ||
505 | =head2 $Carp::CarpLevel | |
0cda2667 | 506 | |
d735c2ef BT |
507 | This variable determines how many additional call frames are to be |
508 | skipped that would not otherwise be when reporting where an error | |
509 | occurred on a call to one of C<Carp>'s functions. It is fairly easy | |
510 | to count these call frames on calls that generate a full stack | |
511 | backtrace. However it is much harder to do this accounting for calls | |
512 | that generate a short message. Usually people skip too many call | |
513 | frames. If they are lucky they skip enough that C<Carp> goes all of | |
514 | the way through the call stack, realizes that something is wrong, and | |
515 | then generates a full stack backtrace. If they are unlucky then the | |
516 | error is reported from somewhere misleading very high in the call | |
517 | stack. | |
518 | ||
519 | Therefore it is best to avoid C<$Carp::CarpLevel>. Instead use | |
3b46207f | 520 | C<@CARP_NOT>, C<%Carp::Internal> and C<%Carp::CarpInternal>. |
0cda2667 DM |
521 | |
522 | Defaults to C<0>. | |
523 | ||
0cda2667 DM |
524 | =head1 BUGS |
525 | ||
526 | The Carp routines don't handle exception objects currently. | |
527 | If called with a first argument that is a reference, they simply | |
528 | call die() or warn(), as appropriate. | |
529 |