1package diagnostics; 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 30perl compiler and the perl interpreter, augmenting them with the more 31explicative and endearing descriptions found in L<perldiag>. Like the 32other pragmata, it affects the compilation phase of your program rather 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 their 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 51any other diagnostics. The $diagnostics::PRETTY variable can generate nicer 52escape sequences for pagers. 53 54Warnings dispatched from perl itself (or more accurately, those that match 55descriptions found in L<perldiag>) are only displayed once (no duplicate 56descriptions). User code generated warnings ala warn() are unaffected, 57allowing duplicate user messages to be displayed. 58 59=head2 The I<splain> Program 60 61While apparently a whole nuther program, I<splain> is actually nothing 62more than a link to the (executable) F<diagnostics.pm> module, as well as 63a link to the F<diagnostics.pod> documentation. The B<-v> flag is like 64the C<use diagnostics -verbose> directive. 65The B<-p> flag is like the 66$diagnostics::PRETTY variable. Since you're post-processing with 67I<splain>, there's no sense in being able to enable() or disable() processing. 68 69Output from I<splain> is directed to B<STDOUT>, unlike the pragma. 70 71=head1 EXAMPLES 72 73The following file is certain to trigger a few errors at both 74runtime and compiletime: 75 76 use diagnostics; 77 print NOWHERE "nothing\n"; 78 print STDERR "\n\tThis message should be unadorned.\n"; 79 warn "\tThis is a user warning"; 80 print "\nDIAGNOSTIC TESTER: Please enter a <CR> here: "; 81 my $a, $b = scalar <STDIN>; 82 print "\n"; 83 print $x/$y; 84 85If you prefer to run your program first and look at its problem 86afterwards, do this: 87 88 perl -w test.pl 2>test.out 89 ./splain < test.out 90 91Note that this is not in general possible in shells of more dubious heritage, 92as the theoretical 93 94 (perl -w test.pl >/dev/tty) >& test.out 95 ./splain < test.out 96 97Because you just moved the existing B<stdout> to somewhere else. 98 99If you don't want to modify your source code, but still have on-the-fly 100warnings, do this: 101 102 exec 3>&1; perl -w test.pl 2>&1 1>&3 3>&- | splain 1>&2 3>&- 103 104Nifty, eh? 105 106If you want to control warnings on the fly, do something like this. 107Make sure you do the C<use> first, or you won't be able to get 108at the enable() or disable() methods. 109 110 use diagnostics; # checks entire compilation phase 111 print "\ntime for 1st bogus diags: SQUAWKINGS\n"; 112 print BOGUS1 'nada'; 113 print "done with 1st bogus\n"; 114 115 disable diagnostics; # only turns off runtime warnings 116 print "\ntime for 2nd bogus: (squelched)\n"; 117 print BOGUS2 'nada'; 118 print "done with 2nd bogus\n"; 119 120 enable diagnostics; # turns back on runtime warnings 121 print "\ntime for 3rd bogus: SQUAWKINGS\n"; 122 print BOGUS3 'nada'; 123 print "done with 3rd bogus\n"; 124 125 disable diagnostics; 126 print "\ntime for 4th bogus: (squelched)\n"; 127 print BOGUS4 'nada'; 128 print "done with 4th bogus\n"; 129 130=head1 INTERNALS 131 132Diagnostic messages derive from the F<perldiag.pod> file when available at 133runtime. Otherwise, they may be embedded in the file itself when the 134splain package is built. See the F<Makefile> for details. 135 136If an extant $SIG{__WARN__} handler is discovered, it will continue 137to be honored, but only after the diagnostics::splainthis() function 138(the module's $SIG{__WARN__} interceptor) has had its way with your 139warnings. 140 141There is a $diagnostics::DEBUG variable you may set if you're desperately 142curious what sorts of things are being intercepted. 143 144 BEGIN { $diagnostics::DEBUG = 1 } 145 146 147=head1 BUGS 148 149Not being able to say "no diagnostics" is annoying, but may not be 150insurmountable. 151 152The C<-pretty> directive is called too late to affect matters. 153You have to do this instead, and I<before> you load the module. 154 155 BEGIN { $diagnostics::PRETTY = 1 } 156 157I could start up faster by delaying compilation until it should be 158needed, but this gets a "panic: top_level" when using the pragma form 159in Perl 5.001e. 160 161While it's true that this documentation is somewhat subserious, if you use 162a program named I<splain>, you should expect a bit of whimsy. 163 164=head1 AUTHOR 165 166Tom Christiansen <F<tchrist@mox.perl.com>>, 25 June 1995. 167 168=cut 169 170use strict; 171use 5.005_64; 172use Carp; 173 174our $VERSION = v1.0; 175our $DEBUG; 176our $VERBOSE; 177our $PRETTY; 178 179use Config; 180my($privlib, $archlib) = @Config{qw(privlibexp archlibexp)}; 181if ($^O eq 'VMS') { 182 require VMS::Filespec; 183 $privlib = VMS::Filespec::unixify($privlib); 184 $archlib = VMS::Filespec::unixify($archlib); 185} 186my @trypod = ( 187 "$archlib/pod/perldiag.pod", 188 "$privlib/pod/perldiag-$Config{version}.pod", 189 "$privlib/pod/perldiag.pod", 190 "$archlib/pods/perldiag.pod", 191 "$privlib/pods/perldiag-$Config{version}.pod", 192 "$privlib/pods/perldiag.pod", 193 ); 194# handy for development testing of new warnings etc 195unshift @trypod, "./pod/perldiag.pod" if -e "pod/perldiag.pod"; 196(my $PODFILE) = ((grep { -e } @trypod), $trypod[$#trypod])[0]; 197 198$DEBUG ||= 0; 199my $WHOAMI = ref bless []; # nobody's business, prolly not even mine 200 201local $| = 1; 202local $_; 203 204my $standalone; 205my(%HTML_2_Troff, %HTML_2_Latin_1, %HTML_2_ASCII_7); 206 207CONFIG: { 208 our $opt_p = our $opt_d = our $opt_v = our $opt_f = ''; 209 210 unless (caller) { 211 $standalone++; 212 require Getopt::Std; 213 Getopt::Std::getopts('pdvf:') 214 or die "Usage: $0 [-v] [-p] [-f splainpod]"; 215 $PODFILE = $opt_f if $opt_f; 216 $DEBUG = 2 if $opt_d; 217 $VERBOSE = $opt_v; 218 $PRETTY = $opt_p; 219 } 220 221 if (open(POD_DIAG, $PODFILE)) { 222 warn "Happy happy podfile from real $PODFILE\n" if $DEBUG; 223 last CONFIG; 224 } 225 226 if (caller) { 227 INCPATH: { 228 for my $file ( (map { "$_/$WHOAMI.pm" } @INC), $0) { 229 warn "Checking $file\n" if $DEBUG; 230 if (open(POD_DIAG, $file)) { 231 while (<POD_DIAG>) { 232 next unless 233 /^__END__\s*# wish diag dbase were more accessible/; 234 print STDERR "podfile is $file\n" if $DEBUG; 235 last INCPATH; 236 } 237 } 238 } 239 } 240 } else { 241 print STDERR "podfile is <DATA>\n" if $DEBUG; 242 *POD_DIAG = *main::DATA; 243 } 244} 245if (eof(POD_DIAG)) { 246 die "couldn't find diagnostic data in $PODFILE @INC $0"; 247} 248 249 250%HTML_2_Troff = ( 251 'amp' => '&', # ampersand 252 'lt' => '<', # left chevron, less-than 253 'gt' => '>', # right chevron, greater-than 254 'quot' => '"', # double quote 255 256 "Aacute" => "A\\*'", # capital A, acute accent 257 # etc 258 259); 260 261%HTML_2_Latin_1 = ( 262 'amp' => '&', # ampersand 263 'lt' => '<', # left chevron, less-than 264 'gt' => '>', # right chevron, greater-than 265 'quot' => '"', # double quote 266 267 "Aacute" => "\xC1" # capital A, acute accent 268 269 # etc 270); 271 272%HTML_2_ASCII_7 = ( 273 'amp' => '&', # ampersand 274 'lt' => '<', # left chevron, less-than 275 'gt' => '>', # right chevron, greater-than 276 'quot' => '"', # double quote 277 278 "Aacute" => "A" # capital A, acute accent 279 # etc 280); 281 282our %HTML_Escapes; 283*HTML_Escapes = do { 284 if ($standalone) { 285 $PRETTY ? \%HTML_2_Latin_1 : \%HTML_2_ASCII_7; 286 } else { 287 \%HTML_2_Latin_1; 288 } 289}; 290 291*THITHER = $standalone ? *STDOUT : *STDERR; 292 293my $transmo = <<EOFUNC; 294sub transmo { 295 #local \$^W = 0; # recursive warnings we do NOT need! 296 study; 297EOFUNC 298 299my %msg; 300{ 301 print STDERR "FINISHING COMPILATION for $_\n" if $DEBUG; 302 local $/ = ''; 303 local $_; 304 my $header; 305 my $for_item; 306 while (<POD_DIAG>) { 307 308 unescape(); 309 if ($PRETTY) { 310 sub noop { return $_[0] } # spensive for a noop 311 sub bold { my $str =$_[0]; $str =~ s/(.)/$1\b$1/g; return $str; } 312 sub italic { my $str = $_[0]; $str =~ s/(.)/_\b$1/g; return $str; } 313 s/[BC]<(.*?)>/bold($1)/ges; 314 s/[LIF]<(.*?)>/italic($1)/ges; 315 } else { 316 s/[BC]<(.*?)>/$1/gs; 317 s/[LIF]<(.*?)>/$1/gs; 318 } 319 unless (/^=/) { 320 if (defined $header) { 321 if ( $header eq 'DESCRIPTION' && 322 ( /Optional warnings are enabled/ 323 || /Some of these messages are generic./ 324 ) ) 325 { 326 next; 327 } 328 s/^/ /gm; 329 $msg{$header} .= $_; 330 undef $for_item; 331 } 332 next; 333 } 334 unless ( s/=item (.*?)\s*\z//) { 335 336 if ( s/=head1\sDESCRIPTION//) { 337 $msg{$header = 'DESCRIPTION'} = ''; 338 undef $for_item; 339 } 340 elsif( s/^=for\s+diagnostics\s*\n(.*?)\s*\z// ) { 341 $for_item = $1; 342 } 343 next; 344 } 345 346 # strip formatting directives in =item line 347 $header = $for_item || $1; 348 undef $for_item; 349 $header =~ s/[A-Z]<(.*?)>/$1/g; 350 351 if ($header =~ /%[csd]/) { 352 my $rhs = my $lhs = $header; 353 if ($lhs =~ s/(.*?)%d(?!%d)(.*)/\Q$1\E-?\\d+\Q$2\E/g) { 354 $lhs =~ s/\\%s/.*?/g; 355 } else { 356 # if i had lookbehind negations, 357 # i wouldn't have to do this \377 noise 358 $lhs =~ s/(.*?)%s/\Q$1\E.*?\377/g; 359 $lhs =~ s/\377([^\377]*)$/\Q$1\E/; 360 $lhs =~ s/\377//g; 361 $lhs =~ s/\.\*\?$/.*/; # Allow %s at the end to eat it all 362 } 363 $lhs =~ s/\\%c/./g; 364 $transmo .= " s{^$lhs}\n {\Q$rhs\E}s\n\t&& return 1;\n"; 365 } else { 366 $transmo .= " m{^\Q$header\E} && return 1;\n"; 367 } 368 369 print STDERR "$WHOAMI: Duplicate entry: \"$header\"\n" 370 if $msg{$header}; 371 372 $msg{$header} = ''; 373 } 374 375 376 close POD_DIAG unless *main::DATA eq *POD_DIAG; 377 378 die "No diagnostics?" unless %msg; 379 380 $transmo .= " return 0;\n}\n"; 381 print STDERR $transmo if $DEBUG; 382 eval $transmo; 383 die $@ if $@; 384} 385 386if ($standalone) { 387 if (!@ARGV and -t STDIN) { print STDERR "$0: Reading from STDIN\n" } 388 while (defined (my $error = <>)) { 389 splainthis($error) || print THITHER $error; 390 } 391 exit; 392} 393 394my $olddie; 395my $oldwarn; 396 397sub import { 398 shift; 399 $^W = 1; # yup, clobbered the global variable; 400 # tough, if you want diags, you want diags. 401 return if $SIG{__WARN__} eq \&warn_trap; 402 403 for (@_) { 404 405 /^-d(ebug)?$/ && do { 406 $DEBUG++; 407 next; 408 }; 409 410 /^-v(erbose)?$/ && do { 411 $VERBOSE++; 412 next; 413 }; 414 415 /^-p(retty)?$/ && do { 416 print STDERR "$0: I'm afraid it's too late for prettiness.\n"; 417 $PRETTY++; 418 next; 419 }; 420 421 warn "Unknown flag: $_"; 422 } 423 424 $oldwarn = $SIG{__WARN__}; 425 $olddie = $SIG{__DIE__}; 426 $SIG{__WARN__} = \&warn_trap; 427 $SIG{__DIE__} = \&death_trap; 428} 429 430sub enable { &import } 431 432sub disable { 433 shift; 434 return unless $SIG{__WARN__} eq \&warn_trap; 435 $SIG{__WARN__} = $oldwarn || ''; 436 $SIG{__DIE__} = $olddie || ''; 437} 438 439sub warn_trap { 440 my $warning = $_[0]; 441 if (caller eq $WHOAMI or !splainthis($warning)) { 442 print STDERR $warning; 443 } 444 &$oldwarn if defined $oldwarn and $oldwarn and $oldwarn ne \&warn_trap; 445}; 446 447sub death_trap { 448 my $exception = $_[0]; 449 450 # See if we are coming from anywhere within an eval. If so we don't 451 # want to explain the exception because it's going to get caught. 452 my $in_eval = 0; 453 my $i = 0; 454 while (1) { 455 my $caller = (caller($i++))[3] or last; 456 if ($caller eq '(eval)') { 457 $in_eval = 1; 458 last; 459 } 460 } 461 462 splainthis($exception) unless $in_eval; 463 if (caller eq $WHOAMI) { print STDERR "INTERNAL EXCEPTION: $exception"; } 464 &$olddie if defined $olddie and $olddie and $olddie ne \&death_trap; 465 466 # We don't want to unset these if we're coming from an eval because 467 # then we've turned off diagnostics. (Actually what does this next 468 # line do? -PSeibel) 469 $SIG{__DIE__} = $SIG{__WARN__} = '' unless $in_eval; 470 local($Carp::CarpLevel) = 1; 471 confess "Uncaught exception from user code:\n\t$exception"; 472 # up we go; where we stop, nobody knows, but i think we die now 473 # but i'm deeply afraid of the &$olddie guy reraising and us getting 474 # into an indirect recursion loop 475}; 476 477my %exact_duplicate; 478my %old_diag; 479my $count; 480my $wantspace; 481sub splainthis { 482 local $_ = shift; 483 local $\; 484 ### &finish_compilation unless %msg; 485 s/\.?\n+$//; 486 my $orig = $_; 487 # return unless defined; 488 s/, <.*?> (?:line|chunk).*$//; 489 my $real = s/(.*?) at .*? (?:line|chunk) \d+.*/$1/; 490 s/^\((.*)\)$/$1/; 491 if ($exact_duplicate{$orig}++) { 492 return &transmo; 493 } 494 else { 495 return 0 unless &transmo; 496 } 497 $orig = shorten($orig); 498 if ($old_diag{$_}) { 499 autodescribe(); 500 print THITHER "$orig (#$old_diag{$_})\n"; 501 $wantspace = 1; 502 } else { 503 autodescribe(); 504 $old_diag{$_} = ++$count; 505 print THITHER "\n" if $wantspace; 506 $wantspace = 0; 507 print THITHER "$orig (#$old_diag{$_})\n"; 508 if ($msg{$_}) { 509 print THITHER $msg{$_}; 510 } else { 511 if (0 and $standalone) { 512 print THITHER " **** Error #$old_diag{$_} ", 513 ($real ? "is" : "appears to be"), 514 " an unknown diagnostic message.\n\n"; 515 } 516 return 0; 517 } 518 } 519 return 1; 520} 521 522sub autodescribe { 523 if ($VERBOSE and not $count) { 524 print THITHER &{$PRETTY ? \&bold : \&noop}("DESCRIPTION OF DIAGNOSTICS"), 525 "\n$msg{DESCRIPTION}\n"; 526 } 527} 528 529sub unescape { 530 s { 531 E< 532 ( [A-Za-z]+ ) 533 > 534 } { 535 do { 536 exists $HTML_Escapes{$1} 537 ? do { $HTML_Escapes{$1} } 538 : do { 539 warn "Unknown escape: E<$1> in $_"; 540 "E<$1>"; 541 } 542 } 543 }egx; 544} 545 546sub shorten { 547 my $line = $_[0]; 548 if (length($line) > 79 and index($line, "\n") == -1) { 549 my $space_place = rindex($line, ' ', 79); 550 if ($space_place != -1) { 551 substr($line, $space_place, 1) = "\n\t"; 552 } 553 } 554 return $line; 555} 556 557 5581 unless $standalone; # or it'll complain about itself 559__END__ # wish diag dbase were more accessible 560