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4633a7c4 1package diagnostics;
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2
3=head1 NAME
4
5diagnostics - Perl compiler pragma to force verbose warning diagnostics
6
7splain - standalone program to do the same thing
8
9=head1 SYNOPSIS
10
11As a pragma:
12
13 use diagnostics;
14 use diagnostics -verbose;
15
16 enable diagnostics;
17 disable diagnostics;
18
19Aa a program:
20
21 perl program 2>diag.out
22 splain [-v] [-p] diag.out
23
24
25=head1 DESCRIPTION
26
27=head2 The C<diagnostics> Pragma
28
29This module extends the terse diagnostics normally emitted by both the
1fef88e7 30perl compiler and the perl interpeter, augmenting them with the more
4633a7c4 31explicative and endearing descriptions found in L<perldiag>. Like the
1fef88e7 32other pragmata, it affects the compilation phase of your program rather
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33than merely the execution phase.
34
35To use in your program as a pragma, merely invoke
36
37 use diagnostics;
38
39at the start (or near the start) of your program. (Note
40that this I<does> enable perl's B<-w> flag.) Your whole
41compilation will then be subject(ed :-) to the enhanced diagnostics.
42These still go out B<STDERR>.
43
44Due to the interaction between runtime and compiletime issues,
45and because it's probably not a very good idea anyway,
46you may not use C<no diagnostics> to turn them off at compiletime.
47However, you may control there behaviour at runtime using the
48disable() and enable() methods to turn them off and on respectively.
49
50The B<-verbose> flag first prints out the L<perldiag> introduction before
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51any other diagnostics. The $diagnostics::PRETTY variable can generate nicer
52escape sequences for pagers.
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53
54=head2 The I<splain> Program
55
56While apparently a whole nuther program, I<splain> is actually nothing
57more than a link to the (executable) F<diagnostics.pm> module, as well as
58a link to the F<diagnostics.pod> documentation. The B<-v> flag is like
59the C<use diagnostics -verbose> directive.
60The B<-p> flag is like the
61$diagnostics::PRETTY variable. Since you're post-processing with
62I<splain>, there's no sense in being able to enable() or disable() processing.
63
64Output from I<splain> is directed to B<STDOUT>, unlike the pragma.
65
66=head1 EXAMPLES
67
68The following file is certain to trigger a few errors at both
69runtime and compiletime:
70
71 use diagnostics;
72 print NOWHERE "nothing\n";
73 print STDERR "\n\tThis message should be unadorned.\n";
74 warn "\tThis is a user warning";
75 print "\nDIAGNOSTIC TESTER: Please enter a <CR> here: ";
76 my $a, $b = scalar <STDIN>;
77 print "\n";
78 print $x/$y;
79
80If you prefer to run your program first and look at its problem
81afterwards, do this:
82
83 perl -w test.pl 2>test.out
84 ./splain < test.out
85
86Note that this is not in general possible in shells of more dubious heritage,
1fef88e7 87as the theoretical
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88
89 (perl -w test.pl >/dev/tty) >& test.out
90 ./splain < test.out
91
92Because you just moved the existing B<stdout> to somewhere else.
93
94If you don't want to modify your source code, but still have on-the-fly
95warnings, do this:
96
97 exec 3>&1; perl -w test.pl 2>&1 1>&3 3>&- | splain 1>&2 3>&-
98
99Nifty, eh?
100
101If you want to control warnings on the fly, do something like this.
102Make sure you do the C<use> first, or you won't be able to get
103at the enable() or disable() methods.
104
105 use diagnostics; # checks entire compilation phase
106 print "\ntime for 1st bogus diags: SQUAWKINGS\n";
107 print BOGUS1 'nada';
108 print "done with 1st bogus\n";
109
110 disable diagnostics; # only turns off runtime warnings
111 print "\ntime for 2nd bogus: (squelched)\n";
112 print BOGUS2 'nada';
113 print "done with 2nd bogus\n";
114
115 enable diagnostics; # turns back on runtime warnings
116 print "\ntime for 3rd bogus: SQUAWKINGS\n";
117 print BOGUS3 'nada';
118 print "done with 3rd bogus\n";
119
120 disable diagnostics;
121 print "\ntime for 4th bogus: (squelched)\n";
122 print BOGUS4 'nada';
123 print "done with 4th bogus\n";
124
125=head1 INTERNALS
126
127Diagnostic messages derive from the F<perldiag.pod> file when available at
128runtime. Otherwise, they may be embedded in the file itself when the
129splain package is built. See the F<Makefile> for details.
130
131If an extant $SIG{__WARN__} handler is discovered, it will continue
1fef88e7 132to be honored, but only after the diagnostics::splainthis() function
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133(the module's $SIG{__WARN__} interceptor) has had its way with your
134warnings.
135
136There is a $diagnostics::DEBUG variable you may set if you're desperately
137curious what sorts of things are being intercepted.
138
139 BEGIN { $diagnostics::DEBUG = 1 }
140
141
142=head1 BUGS
143
144Not being able to say "no diagnostics" is annoying, but may not be
145insurmountable.
146
147The C<-pretty> directive is called too late to affect matters.
864e1151 148You have to do this instead, and I<before> you load the module.
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149
150 BEGIN { $diagnostics::PRETTY = 1 }
151
152I could start up faster by delaying compilation until it should be
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153needed, but this gets a "panic: top_level" when using the pragma form
154in Perl 5.001e.
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155
156While it's true that this documentation is somewhat subserious, if you use
157a program named I<splain>, you should expect a bit of whimsy.
158
159=head1 AUTHOR
160
352854fa 161Tom Christiansen <F<tchrist@mox.perl.com>>, 25 June 1995.
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162
163=cut
164
5f05dabc 165require 5.001;
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166use Carp;
167
168use Config;
91a06757 169($privlib, $archlib) = @Config{qw(privlibexp archlibexp)};
5f05dabc 170if ($^O eq 'VMS') {
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171 require VMS::Filespec;
172 $privlib = VMS::Filespec::unixify($privlib);
173 $archlib = VMS::Filespec::unixify($archlib);
5f05dabc 174}
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175@trypod = ("$archlib/pod/perldiag.pod",
176 "$privlib/pod/perldiag-$].pod",
177 "$privlib/pod/perldiag.pod");
178($PODFILE) = ((grep { -e } @trypod), $trypod[$#trypod])[0];
5f05dabc 179
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180$DEBUG ||= 0;
181my $WHOAMI = ref bless []; # nobody's business, prolly not even mine
182
6dab8668 183$| = 1;
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184
185local $_;
186
187CONFIG: {
188 $opt_p = $opt_d = $opt_v = $opt_f = '';
189 %HTML_2_Troff = %HTML_2_Latin_1 = %HTML_2_ASCII_7 = ();
190 %exact_duplicate = ();
191
192 unless (caller) {
193 $standalone++;
194 require Getopt::Std;
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195 Getopt::Std::getopts('pdvf:')
196 or die "Usage: $0 [-v] [-p] [-f splainpod]";
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197 $PODFILE = $opt_f if $opt_f;
198 $DEBUG = 2 if $opt_d;
199 $VERBOSE = $opt_v;
200 $PRETTY = $opt_p;
201 }
202
203 if (open(POD_DIAG, $PODFILE)) {
204 warn "Happy happy podfile from real $PODFILE\n" if $DEBUG;
205 last CONFIG;
206 }
207
208 if (caller) {
209 INCPATH: {
210 for $file ( (map { "$_/$WHOAMI.pm" } @INC), $0) {
211 warn "Checking $file\n" if $DEBUG;
212 if (open(POD_DIAG, $file)) {
213 while (<POD_DIAG>) {
214 next unless /^__END__\s*# wish diag dbase were more accessible/;
215 print STDERR "podfile is $file\n" if $DEBUG;
216 last INCPATH;
217 }
218 }
219 }
220 }
221 } else {
222 print STDERR "podfile is <DATA>\n" if $DEBUG;
223 *POD_DIAG = *main::DATA;
224 }
225}
226if (eof(POD_DIAG)) {
227 die "couldn't find diagnostic data in $PODFILE @INC $0";
228}
229
230
231%HTML_2_Troff = (
232 'amp' => '&', # ampersand
233 'lt' => '<', # left chevron, less-than
234 'gt' => '>', # right chevron, greater-than
235 'quot' => '"', # double quote
236
237 "Aacute" => "A\\*'", # capital A, acute accent
238 # etc
239
240);
241
242%HTML_2_Latin_1 = (
243 'amp' => '&', # ampersand
244 'lt' => '<', # left chevron, less-than
245 'gt' => '>', # right chevron, greater-than
246 'quot' => '"', # double quote
247
248 "Aacute" => "\xC1" # capital A, acute accent
249
250 # etc
251);
252
253%HTML_2_ASCII_7 = (
254 'amp' => '&', # ampersand
255 'lt' => '<', # left chevron, less-than
256 'gt' => '>', # right chevron, greater-than
257 'quot' => '"', # double quote
258
259 "Aacute" => "A" # capital A, acute accent
260 # etc
261);
262
263*HTML_Escapes = do {
264 if ($standalone) {
265 $PRETTY ? \%HTML_2_Latin_1 : \%HTML_2_ASCII_7;
266 } else {
267 \%HTML_2_Latin_1;
268 }
269};
270
271*THITHER = $standalone ? *STDOUT : *STDERR;
272
273$transmo = <<EOFUNC;
274sub transmo {
275 local \$^W = 0; # recursive warnings we do NOT need!
276 study;
277EOFUNC
278
279### sub finish_compilation { # 5.001e panic: top_level for embedded version
280 print STDERR "FINISHING COMPILATION for $_\n" if $DEBUG;
281 ### local
282 $RS = '';
283 local $_;
284 while (<POD_DIAG>) {
285 #s/(.*)\n//;
286 #$header = $1;
287
288 unescape();
289 if ($PRETTY) {
290 sub noop { return $_[0] } # spensive for a noop
291 sub bold { my $str =$_[0]; $str =~ s/(.)/$1\b$1/g; return $str; }
292 sub italic { my $str = $_[0]; $str =~ s/(.)/_\b$1/g; return $str; }
293 s/[BC]<(.*?)>/bold($1)/ges;
294 s/[LIF]<(.*?)>/italic($1)/ges;
295 } else {
296 s/[BC]<(.*?)>/$1/gs;
297 s/[LIF]<(.*?)>/$1/gs;
298 }
299 unless (/^=/) {
300 if (defined $header) {
301 if ( $header eq 'DESCRIPTION' &&
302 ( /Optional warnings are enabled/
303 || /Some of these messages are generic./
304 ) )
305 {
306 next;
307 }
308 s/^/ /gm;
309 $msg{$header} .= $_;
310 }
311 next;
312 }
313 unless ( s/=item (.*)\s*\Z//) {
314
315 if ( s/=head1\sDESCRIPTION//) {
316 $msg{$header = 'DESCRIPTION'} = '';
317 }
318 next;
319 }
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320
321 # strip formatting directives in =item line
322 ($header = $1) =~ s/[A-Z]<(.*?)>/$1/g;
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323
324 if ($header =~ /%[sd]/) {
325 $rhs = $lhs = $header;
326 #if ($lhs =~ s/(.*?)%d(?!%d)(.*)/\Q$1\E\\d+\Q$2\E\$/g) {
327 if ($lhs =~ s/(.*?)%d(?!%d)(.*)/\Q$1\E\\d+\Q$2\E/g) {
328 $lhs =~ s/\\%s/.*?/g;
329 } else {
330 # if i had lookbehind negations, i wouldn't have to do this \377 noise
331 $lhs =~ s/(.*?)%s/\Q$1\E.*?\377/g;
332 #$lhs =~ s/\377([^\377]*)$/\Q$1\E\$/;
333 $lhs =~ s/\377([^\377]*)$/\Q$1\E/;
334 $lhs =~ s/\377//g;
e7ea3e70 335 $lhs =~ s/\.\*\?$/.*/; # Allow %s at the end to eat it all
4633a7c4 336 }
e7ea3e70 337 $transmo .= " s{^$lhs}\n {\Q$rhs\E}s\n\t&& return 1;\n";
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338 } else {
339 $transmo .= " m{^\Q$header\E} && return 1;\n";
340 }
341
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342 print STDERR "$WHOAMI: Duplicate entry: \"$header\"\n"
343 if $msg{$header};
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344
345 $msg{$header} = '';
346 }
347
348
349 close POD_DIAG unless *main::DATA eq *POD_DIAG;
350
351 die "No diagnostics?" unless %msg;
352
353 $transmo .= " return 0;\n}\n";
354 print STDERR $transmo if $DEBUG;
355 eval $transmo;
356 die $@ if $@;
357 $RS = "\n";
358### }
359
360if ($standalone) {
361 if (!@ARGV and -t STDIN) { print STDERR "$0: Reading from STDIN\n" }
40da2db3 362 while (defined ($error = <>)) {
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363 splainthis($error) || print THITHER $error;
364 }
365 exit;
366} else {
367 $old_w = 0; $oldwarn = ''; $olddie = '';
368}
369
370sub import {
371 shift;
372 $old_w = $^W;
373 $^W = 1; # yup, clobbered the global variable; tough, if you
374 # want diags, you want diags.
375 return if $SIG{__WARN__} eq \&warn_trap;
376
377 for (@_) {
378
379 /^-d(ebug)?$/ && do {
380 $DEBUG++;
381 next;
382 };
383
384 /^-v(erbose)?$/ && do {
385 $VERBOSE++;
386 next;
387 };
388
389 /^-p(retty)?$/ && do {
390 print STDERR "$0: I'm afraid it's too late for prettiness.\n";
391 $PRETTY++;
392 next;
393 };
394
395 warn "Unknown flag: $_";
396 }
397
398 $oldwarn = $SIG{__WARN__};
399 $olddie = $SIG{__DIE__};
400 $SIG{__WARN__} = \&warn_trap;
401 $SIG{__DIE__} = \&death_trap;
402}
403
404sub enable { &import }
405
406sub disable {
407 shift;
408 $^W = $old_w;
409 return unless $SIG{__WARN__} eq \&warn_trap;
410 $SIG{__WARN__} = $oldwarn;
411 $SIG{__DIE__} = $olddie;
412}
413
414sub warn_trap {
415 my $warning = $_[0];
416 if (caller eq $WHOAMI or !splainthis($warning)) {
417 print STDERR $warning;
418 }
37120919 419 &$oldwarn if defined $oldwarn and $oldwarn and $oldwarn ne \&warn_trap;
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420};
421
422sub death_trap {
423 my $exception = $_[0];
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424
425 # See if we are coming from anywhere within an eval. If so we don't
426 # want to explain the exception because it's going to get caught.
427 my $in_eval = 0;
428 my $i = 0;
429 while (1) {
430 my $caller = (caller($i++))[3] or last;
431 if ($caller eq '(eval)') {
432 $in_eval = 1;
433 last;
434 }
435 }
436
437 splainthis($exception) unless $in_eval;
4633a7c4 438 if (caller eq $WHOAMI) { print STDERR "INTERNAL EXCEPTION: $exception"; }
37120919 439 &$olddie if defined $olddie and $olddie and $olddie ne \&death_trap;
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440
441 # We don't want to unset these if we're coming from an eval because
442 # then we've turned off diagnostics. (Actually what does this next
443 # line do? -PSeibel)
444 $SIG{__DIE__} = $SIG{__WARN__} = '' unless $in_eval;
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445 local($Carp::CarpLevel) = 1;
446 confess "Uncaught exception from user code:\n\t$exception";
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447 # up we go; where we stop, nobody knows, but i think we die now
448 # but i'm deeply afraid of the &$olddie guy reraising and us getting
449 # into an indirect recursion loop
450};
451
452sub splainthis {
453 local $_ = shift;
454 ### &finish_compilation unless %msg;
455 s/\.?\n+$//;
456 my $orig = $_;
457 # return unless defined;
458 if ($exact_duplicate{$_}++) {
459 return 1;
460 }
461 s/, <.*?> (?:line|chunk).*$//;
462 $real = s/(.*?) at .*? (?:line|chunk) \d+.*/$1/;
463 s/^\((.*)\)$/$1/;
464 return 0 unless &transmo;
465 $orig = shorten($orig);
466 if ($old_diag{$_}) {
467 autodescribe();
468 print THITHER "$orig (#$old_diag{$_})\n";
469 $wantspace = 1;
470 } else {
471 autodescribe();
472 $old_diag{$_} = ++$count;
473 print THITHER "\n" if $wantspace;
474 $wantspace = 0;
475 print THITHER "$orig (#$old_diag{$_})\n";
476 if ($msg{$_}) {
477 print THITHER $msg{$_};
478 } else {
479 if (0 and $standalone) {
480 print THITHER " **** Error #$old_diag{$_} ",
481 ($real ? "is" : "appears to be"),
482 " an unknown diagnostic message.\n\n";
483 }
484 return 0;
485 }
486 }
487 return 1;
488}
489
490sub autodescribe {
491 if ($VERBOSE and not $count) {
492 print THITHER &{$PRETTY ? \&bold : \&noop}("DESCRIPTION OF DIAGNOSTICS"),
493 "\n$msg{DESCRIPTION}\n";
494 }
495}
496
497sub unescape {
498 s {
499 E<
500 ( [A-Za-z]+ )
501 >
502 } {
503 do {
504 exists $HTML_Escapes{$1}
505 ? do { $HTML_Escapes{$1} }
506 : do {
f02a87df 507 warn "Unknown escape: E<$1> in $_";
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508 "E<$1>";
509 }
510 }
511 }egx;
512}
513
514sub shorten {
515 my $line = $_[0];
774d564b 516 if (length($line) > 79 and index($line, "\n") == -1) {
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517 my $space_place = rindex($line, ' ', 79);
518 if ($space_place != -1) {
519 substr($line, $space_place, 1) = "\n\t";
520 }
521 }
522 return $line;
523}
524
525
526# have to do this: RS isn't set until run time, but we're executing at compile time
527$RS = "\n";
528
5291 unless $standalone; # or it'll complain about itself
530__END__ # wish diag dbase were more accessible