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Edit File: splain
#!/usr/bin/perl eval 'exec /usr/bin/perl -S $0 ${1+"$@"}' if $running_under_some_shell; BEGIN { pop @INC if $INC[-1] eq '.' } =head1 NAME diagnostics, splain - produce verbose warning diagnostics =head1 SYNOPSIS Using the C<diagnostics> pragma: use diagnostics; use diagnostics -verbose; enable diagnostics; disable diagnostics; Using the C<splain> standalone filter program: perl program 2>diag.out splain [-v] [-p] diag.out Using diagnostics to get stack traces from a misbehaving script: perl -Mdiagnostics=-traceonly my_script.pl =head1 DESCRIPTION =head2 The C<diagnostics> Pragma This module extends the terse diagnostics normally emitted by both the perl compiler and the perl interpreter (from running perl with a -w switch or C<use warnings>), augmenting them with the more explicative and endearing descriptions found in L<perldiag>. Like the other pragmata, it affects the compilation phase of your program rather than merely the execution phase. To use in your program as a pragma, merely invoke use diagnostics; at the start (or near the start) of your program. (Note that this I<does> enable perl's B<-w> flag.) Your whole compilation will then be subject(ed :-) to the enhanced diagnostics. These still go out B<STDERR>. Due to the interaction between runtime and compiletime issues, and because it's probably not a very good idea anyway, you may not use C<no diagnostics> to turn them off at compiletime. However, you may control their behaviour at runtime using the disable() and enable() methods to turn them off and on respectively. The B<-verbose> flag first prints out the L<perldiag> introduction before any other diagnostics. The $diagnostics::PRETTY variable can generate nicer escape sequences for pagers. Warnings dispatched from perl itself (or more accurately, those that match descriptions found in L<perldiag>) are only displayed once (no duplicate descriptions). User code generated warnings a la warn() are unaffected, allowing duplicate user messages to be displayed. This module also adds a stack trace to the error message when perl dies. This is useful for pinpointing what caused the death. The B<-traceonly> (or just B<-t>) flag turns off the explanations of warning messages leaving just the stack traces. So if your script is dieing, run it again with perl -Mdiagnostics=-traceonly my_bad_script to see the call stack at the time of death. By supplying the B<-warntrace> (or just B<-w>) flag, any warnings emitted will also come with a stack trace. =head2 The I<splain> Program While apparently a whole nuther program, I<splain> is actually nothing more than a link to the (executable) F<diagnostics.pm> module, as well as a link to the F<diagnostics.pod> documentation. The B<-v> flag is like the C<use diagnostics -verbose> directive. The B<-p> flag is like the $diagnostics::PRETTY variable. Since you're post-processing with I<splain>, there's no sense in being able to enable() or disable() processing. Output from I<splain> is directed to B<STDOUT>, unlike the pragma. =head1 EXAMPLES The following file is certain to trigger a few errors at both runtime and compiletime: use diagnostics; print NOWHERE "nothing\n"; print STDERR "\n\tThis message should be unadorned.\n"; warn "\tThis is a user warning"; print "\nDIAGNOSTIC TESTER: Please enter a <CR> here: "; my $a, $b = scalar <STDIN>; print "\n"; print $x/$y; If you prefer to run your program first and look at its problem afterwards, do this: perl -w test.pl 2>test.out ./splain < test.out Note that this is not in general possible in shells of more dubious heritage, as the theoretical (perl -w test.pl >/dev/tty) >& test.out ./splain < test.out Because you just moved the existing B<stdout> to somewhere else. If you don't want to modify your source code, but still have on-the-fly warnings, do this: exec 3>&1; perl -w test.pl 2>&1 1>&3 3>&- | splain 1>&2 3>&- Nifty, eh? If you want to control warnings on the fly, do something like this. Make sure you do the C<use> first, or you won't be able to get at the enable() or disable() methods. use diagnostics; # checks entire compilation phase print "\ntime for 1st bogus diags: SQUAWKINGS\n"; print BOGUS1 'nada'; print "done with 1st bogus\n"; disable diagnostics; # only turns off runtime warnings print "\ntime for 2nd bogus: (squelched)\n"; print BOGUS2 'nada'; print "done with 2nd bogus\n"; enable diagnostics; # turns back on runtime warnings print "\ntime for 3rd bogus: SQUAWKINGS\n"; print BOGUS3 'nada'; print "done with 3rd bogus\n"; disable diagnostics; print "\ntime for 4th bogus: (squelched)\n"; print BOGUS4 'nada'; print "done with 4th bogus\n"; =head1 INTERNALS Diagnostic messages derive from the F<perldiag.pod> file when available at runtime. Otherwise, they may be embedded in the file itself when the splain package is built. See the F<Makefile> for details. If an extant $SIG{__WARN__} handler is discovered, it will continue to be honored, but only after the diagnostics::splainthis() function (the module's $SIG{__WARN__} interceptor) has had its way with your warnings. There is a $diagnostics::DEBUG variable you may set if you're desperately curious what sorts of things are being intercepted. BEGIN { $diagnostics::DEBUG = 1 } =head1 BUGS Not being able to say "no diagnostics" is annoying, but may not be insurmountable. The C<-pretty> directive is called too late to affect matters. You have to do this instead, and I<before> you load the module. BEGIN { $diagnostics::PRETTY = 1 } I could start up faster by delaying compilation until it should be needed, but this gets a "panic: top_level" when using the pragma form in Perl 5.001e. While it's true that this documentation is somewhat subserious, if you use a program named I<splain>, you should expect a bit of whimsy. =head1 AUTHOR Tom Christiansen <F<tchrist@mox.perl.com>>, 25 June 1995. =cut use strict; use 5.009001; use Carp; $Carp::Internal{__PACKAGE__.""}++; our $VERSION = '1.37'; our $DEBUG; our $VERBOSE; our $PRETTY; our $TRACEONLY = 0; our $WARNTRACE = 0; use Config; use Text::Tabs 'expand'; my $privlib = $Config{privlibexp}; if ($^O eq 'VMS') { require VMS::Filespec; $privlib = VMS::Filespec::unixify($privlib); } my @trypod = ( "$privlib/pod/perldiag.pod", "$privlib/pods/perldiag.pod", ); # handy for development testing of new warnings etc unshift @trypod, "./pod/perldiag.pod" if -e "pod/perldiag.pod"; (my $PODFILE) = ((grep { -e } @trypod), $trypod[$#trypod])[0]; $DEBUG ||= 0; local $| = 1; local $_; local $.; my $standalone; my(%HTML_2_Troff, %HTML_2_Latin_1, %HTML_2_ASCII_7); CONFIG: { our $opt_p = our $opt_d = our $opt_v = our $opt_f = ''; unless (caller) { $standalone++; require Getopt::Std; Getopt::Std::getopts('pdvf:') or die "Usage: $0 [-v] [-p] [-f splainpod]"; $PODFILE = $opt_f if $opt_f; $DEBUG = 2 if $opt_d; $VERBOSE = $opt_v; $PRETTY = $opt_p; } if (open(POD_DIAG, '<', $PODFILE)) { warn "Happy happy podfile from real $PODFILE\n" if $DEBUG; last CONFIG; } if (caller) { INCPATH: { for my $file ( (map { "$_/".__PACKAGE__.".pm" } @INC), $0) { warn "Checking $file\n" if $DEBUG; if (open(POD_DIAG, '<', $file)) { while (<POD_DIAG>) { next unless /^__END__\s*# wish diag dbase were more accessible/; print STDERR "podfile is $file\n" if $DEBUG; last INCPATH; } } } } } else { print STDERR "podfile is <DATA>\n" if $DEBUG; *POD_DIAG = *main::DATA; } } if (eof(POD_DIAG)) { die "couldn't find diagnostic data in $PODFILE @INC $0"; } %HTML_2_Troff = ( 'amp' => '&', # ampersand 'lt' => '<', # left chevron, less-than 'gt' => '>', # right chevron, greater-than 'quot' => '"', # double quote 'sol' => '/', # forward slash / solidus 'verbar' => '|', # vertical bar "Aacute" => "A\\*'", # capital A, acute accent # etc ); %HTML_2_Latin_1 = ( 'amp' => '&', # ampersand 'lt' => '<', # left chevron, less-than 'gt' => '>', # right chevron, greater-than 'quot' => '"', # double quote 'sol' => '/', # Forward slash / solidus 'verbar' => '|', # vertical bar "Aacute" => "\xC1" # capital A, acute accent # etc ); %HTML_2_ASCII_7 = ( 'amp' => '&', # ampersand 'lt' => '<', # left chevron, less-than 'gt' => '>', # right chevron, greater-than 'quot' => '"', # double quote 'sol' => '/', # Forward slash / solidus 'verbar' => '|', # vertical bar "Aacute" => "A" # capital A, acute accent # etc ); our %HTML_Escapes; *HTML_Escapes = do { if ($standalone) { $PRETTY ? \%HTML_2_Latin_1 : \%HTML_2_ASCII_7; } else { \%HTML_2_Latin_1; } }; *THITHER = $standalone ? *STDOUT : *STDERR; my %transfmt = (); my $transmo = <<EOFUNC; sub transmo { #local \$^W = 0; # recursive warnings we do NOT need! EOFUNC my %msg; my $over_level = 0; # We look only at =item lines at the first =over level { print STDERR "FINISHING COMPILATION for $_\n" if $DEBUG; local $/ = ''; local $_; my $header; my @headers; my $for_item; my $seen_body; while (<POD_DIAG>) { sub _split_pod_link { $_[0] =~ m'(?:([^|]*)\|)?([^/]*)(?:/("?)(.*)\3)?'s; ($1,$2,$4); } unescape(); if ($PRETTY) { sub noop { return $_[0] } # spensive for a noop sub bold { my $str =$_[0]; $str =~ s/(.)/$1\b$1/g; return $str; } sub italic { my $str = $_[0]; $str =~ s/(.)/_\b$1/g; return $str; } s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/bold($+)/ges; s/[IF]<(.*?)>/italic($1)/ges; s/L<(.*?)>/ my($text,$page,$sect) = _split_pod_link($1); defined $text ? $text : defined $sect ? italic($sect) . ' in ' . italic($page) : italic($page) /ges; s/S<(.*?)>/ $1 /ges; } else { s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/$+/gs; s/[IF]<(.*?)>/$1/gs; s/L<(.*?)>/ my($text,$page,$sect) = _split_pod_link($1); defined $text ? $text : defined $sect ? qq '"$sect" in $page' : $page /ges; s/S<(.*?)>/ $1 /ges; } unless (/^=/) { if (defined $header) { if ( $header eq 'DESCRIPTION' && ( /Optional warnings are enabled/ || /Some of these messages are generic./ ) ) { next; } $_ = expand $_; s/^/ /gm; $msg{$header} .= $_; for my $h(@headers) { $msg{$h} .= $_ } ++$seen_body; undef $for_item; } next; } # If we have not come across the body of the description yet, then # the previous header needs to share the same description. if ($seen_body) { @headers = (); } else { push @headers, $header if defined $header; } if ( ! s/=item (.*?)\s*\z//s || $over_level != 1) { if ( s/=head1\sDESCRIPTION//) { $msg{$header = 'DESCRIPTION'} = ''; undef $for_item; } elsif( s/^=for\s+diagnostics\s*\n(.*?)\s*\z// ) { $for_item = $1; } elsif( /^=over\b/ ) { $over_level++; } elsif( /^=back\b/ ) { # Stop processing body here $over_level--; if ($over_level == 0) { undef $header; undef $for_item; $seen_body = 0; next; } } next; } if( $for_item ) { $header = $for_item; undef $for_item } else { $header = $1; $header =~ s/\n/ /gs; # Allow multi-line headers } # strip formatting directives from =item line $header =~ s/[A-Z]<(.*?)>/$1/g; # Since we strip "(\.\s*)\n" when we search a warning, strip it here as well $header =~ s/(\.\s*)?$//; my @toks = split( /(%l?[dxX]|%[ucp]|%(?:\.\d+)?[fs])/, $header ); if (@toks > 1) { my $conlen = 0; for my $i (0..$#toks){ if( $i % 2 ){ if( $toks[$i] eq '%c' ){ $toks[$i] = '.'; } elsif( $toks[$i] =~ /^%(?:d|u)$/ ){ $toks[$i] = '\d+'; } elsif( $toks[$i] =~ '^%(?:s|.*f)$' ){ $toks[$i] = $i == $#toks ? '.*' : '.*?'; } elsif( $toks[$i] =~ '%.(\d+)s' ){ $toks[$i] = ".{$1}"; } elsif( $toks[$i] =~ '^%l*([pxX])$' ){ $toks[$i] = $1 eq 'X' ? '[\dA-F]+' : '[\da-f]+'; } } elsif( length( $toks[$i] ) ){ $toks[$i] = quotemeta $toks[$i]; $conlen += length( $toks[$i] ); } } my $lhs = join( '', @toks ); $lhs =~ s/(\\\s)+/\\s+/g; # Replace lit space with multi-space match $transfmt{$header}{pat} = " s^\\s*$lhs\\s*\Q$header\Es\n\t&& return 1;\n"; $transfmt{$header}{len} = $conlen; } else { my $lhs = "\Q$header\E"; $lhs =~ s/(\\\s)+/\\s+/g; # Replace lit space with multi-space match $transfmt{$header}{pat} = " s^\\s*$lhs\\s*\Q$header\E\n\t && return 1;\n"; $transfmt{$header}{len} = length( $header ); } print STDERR __PACKAGE__.": Duplicate entry: \"$header\"\n" if $msg{$header}; $msg{$header} = ''; $seen_body = 0; } close POD_DIAG unless *main::DATA eq *POD_DIAG; die "No diagnostics?" unless %msg; # Apply patterns in order of decreasing sum of lengths of fixed parts # Seems the best way of hitting the right one. for my $hdr ( sort { $transfmt{$b}{len} <=> $transfmt{$a}{len} } keys %transfmt ){ $transmo .= $transfmt{$hdr}{pat}; } $transmo .= " return 0;\n}\n"; print STDERR $transmo if $DEBUG; eval $transmo; die $@ if $@; } if ($standalone) { if (!@ARGV and -t STDIN) { print STDERR "$0: Reading from STDIN\n" } while (defined (my $error = <>)) { splainthis($error) || print THITHER $error; } exit; } my $olddie; my $oldwarn; sub import { shift; $^W = 1; # yup, clobbered the global variable; # tough, if you want diags, you want diags. return if defined $SIG{__WARN__} && ($SIG{__WARN__} eq \&warn_trap); for (@_) { /^-d(ebug)?$/ && do { $DEBUG++; next; }; /^-v(erbose)?$/ && do { $VERBOSE++; next; }; /^-p(retty)?$/ && do { print STDERR "$0: I'm afraid it's too late for prettiness.\n"; $PRETTY++; next; }; # matches trace and traceonly for legacy doc mixup reasons /^-t(race(only)?)?$/ && do { $TRACEONLY++; next; }; /^-w(arntrace)?$/ && do { $WARNTRACE++; next; }; warn "Unknown flag: $_"; } $oldwarn = $SIG{__WARN__}; $olddie = $SIG{__DIE__}; $SIG{__WARN__} = \&warn_trap; $SIG{__DIE__} = \&death_trap; } sub enable { &import } sub disable { shift; return unless $SIG{__WARN__} eq \&warn_trap; $SIG{__WARN__} = $oldwarn || ''; $SIG{__DIE__} = $olddie || ''; } sub warn_trap { my $warning = $_[0]; if (caller eq __PACKAGE__ or !splainthis($warning)) { if ($WARNTRACE) { print STDERR Carp::longmess($warning); } else { print STDERR $warning; } } goto &$oldwarn if defined $oldwarn and $oldwarn and $oldwarn ne \&warn_trap; }; sub death_trap { my $exception = $_[0]; # See if we are coming from anywhere within an eval. If so we don't # want to explain the exception because it's going to get caught. my $in_eval = 0; my $i = 0; while (my $caller = (caller($i++))[3]) { if ($caller eq '(eval)') { $in_eval = 1; last; } } splainthis($exception) unless $in_eval; if (caller eq __PACKAGE__) { print STDERR "INTERNAL EXCEPTION: $exception"; } &$olddie if defined $olddie and $olddie and $olddie ne \&death_trap; return if $in_eval; # We don't want to unset these if we're coming from an eval because # then we've turned off diagnostics. # Switch off our die/warn handlers so we don't wind up in our own # traps. $SIG{__DIE__} = $SIG{__WARN__} = ''; $exception =~ s/\n(?=.)/\n\t/gas; die Carp::longmess("__diagnostics__") =~ s/^__diagnostics__.*?line \d+\.?\n/ "Uncaught exception from user code:\n\t$exception" /re; # up we go; where we stop, nobody knows, but i think we die now # but i'm deeply afraid of the &$olddie guy reraising and us getting # into an indirect recursion loop }; my %exact_duplicate; my %old_diag; my $count; my $wantspace; sub splainthis { return 0 if $TRACEONLY; for (my $tmp = shift) { local $\; local $!; ### &finish_compilation unless %msg; s/(\.\s*)?\n+$//; my $orig = $_; # return unless defined; # get rid of the where-are-we-in-input part s/, <.*?> (?:line|chunk).*$//; # Discard 1st " at <file> line <no>" and all text beyond # but be aware of messages containing " at this-or-that" my $real = 0; my @secs = split( / at / ); return unless @secs; $_ = $secs[0]; for my $i ( 1..$#secs ){ if( $secs[$i] =~ /.+? (?:line|chunk) \d+/ ){ $real = 1; last; } else { $_ .= ' at ' . $secs[$i]; } } # remove parenthesis occurring at the end of some messages s/^\((.*)\)$/$1/; if ($exact_duplicate{$orig}++) { return &transmo; } else { return 0 unless &transmo; } my $short = shorten($orig); if ($old_diag{$_}) { autodescribe(); print THITHER "$short (#$old_diag{$_})\n"; $wantspace = 1; } elsif (!$msg{$_} && $orig =~ /\n./s) { # A multiline message, like "Attempt to reload / # Compilation failed" my $found; for (split /^/, $orig) { splainthis($_) and $found = 1; } return $found; } else { autodescribe(); $old_diag{$_} = ++$count; print THITHER "\n" if $wantspace; $wantspace = 0; print THITHER "$short (#$old_diag{$_})\n"; if ($msg{$_}) { print THITHER $msg{$_}; } else { if (0 and $standalone) { print THITHER " **** Error #$old_diag{$_} ", ($real ? "is" : "appears to be"), " an unknown diagnostic message.\n\n"; } return 0; } } return 1; } } sub autodescribe { if ($VERBOSE and not $count) { print THITHER &{$PRETTY ? \&bold : \&noop}("DESCRIPTION OF DIAGNOSTICS"), "\n$msg{DESCRIPTION}\n"; } } sub unescape { s { E< ( [A-Za-z]+ ) > } { do { exists $HTML_Escapes{$1} ? do { $HTML_Escapes{$1} } : do { warn "Unknown escape: E<$1> in $_"; "E<$1>"; } } }egx; } sub shorten { my $line = $_[0]; if (length($line) > 79 and index($line, "\n") == -1) { my $space_place = rindex($line, ' ', 79); if ($space_place != -1) { substr($line, $space_place, 1) = "\n\t"; } } return $line; } 1 unless $standalone; # or it'll complain about itself __END__ # wish diag dbase were more accessible