package diagnostics; =head1 NAME diagnostics - Perl compiler pragma to force verbose warning diagnostics splain - standalone program to do the same thing =head1 SYNOPSIS As a pragma: use diagnostics; use diagnostics -verbose; enable diagnostics; disable diagnostics; Aa a program: perl program 2>diag.out splain [-v] [-p] diag.out =head1 DESCRIPTION =head2 The C Pragma This module extends the terse diagnostics normally emitted by both the perl compiler and the perl interpreter, augmenting them with the more explicative and endearing descriptions found in L. 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 enable perl's B<-w> flag.) Your whole compilation will then be subject(ed :-) to the enhanced diagnostics. These still go out B. 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 to turn them off at compiletime. However, you may control there 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 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) are only displayed once (no duplicate descriptions). User code generated warnings ala warn() are unaffected, allowing duplicate user messages to be displayed. =head2 The I Program While apparently a whole nuther program, I is actually nothing more than a link to the (executable) F module, as well as a link to the F documentation. The B<-v> flag is like the C directive. The B<-p> flag is like the $diagnostics::PRETTY variable. Since you're post-processing with I, there's no sense in being able to enable() or disable() processing. Output from I is directed to B, 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 here: "; my $a, $b = scalar ; 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 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 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 file when available at runtime. Otherwise, they may be embedded in the file itself when the splain package is built. See the F 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 you load the module. BEGIN { $diagnostics::PRETTY = 1 } I could start up faster by delaying compilation until it should be needed, but this gets a "panic: top_level" when using the pragma form in Perl 5.001e. While it's true that this documentation is somewhat subserious, if you use a program named I, you should expect a bit of whimsy. =head1 AUTHOR Tom Christiansen >, 25 June 1995. =cut require 5.001; use Carp; use Config; ($privlib, $archlib) = @Config{qw(privlibexp archlibexp)}; if ($^O eq 'VMS') { require VMS::Filespec; $privlib = VMS::Filespec::unixify($privlib); $archlib = VMS::Filespec::unixify($archlib); } @trypod = ("$archlib/pod/perldiag.pod", "$privlib/pod/perldiag-$].pod", "$privlib/pod/perldiag.pod"); # handy for development testing of new warnings etc unshift @trypod, "./pod/perldiag.pod" if -e "pod/perldiag.pod"; ($PODFILE) = ((grep { -e } @trypod), $trypod[$#trypod])[0]; $DEBUG ||= 0; my $WHOAMI = ref bless []; # nobody's business, prolly not even mine $| = 1; local $_; CONFIG: { $opt_p = $opt_d = $opt_v = $opt_f = ''; %HTML_2_Troff = %HTML_2_Latin_1 = %HTML_2_ASCII_7 = (); %exact_duplicate = (); 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 $file ( (map { "$_/$WHOAMI.pm" } @INC), $0) { warn "Checking $file\n" if $DEBUG; if (open(POD_DIAG, $file)) { while () { 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 \n" if $DEBUG; *POD_DIAG = *main::DATA; } } if (eof(POD_DIAG)) { die "couldn't find diagnostic data in $PODFILE @INC $0"; } %HTML_2_Troff = ( 'amp' => '&', # ampersand 'lt' => '<', # left chevron, less-than 'gt' => '>', # right chevron, greater-than 'quot' => '"', # double quote "Aacute" => "A\\*'", # capital A, acute accent # etc ); %HTML_2_Latin_1 = ( 'amp' => '&', # ampersand 'lt' => '<', # left chevron, less-than 'gt' => '>', # right chevron, greater-than 'quot' => '"', # double quote "Aacute" => "\xC1" # capital A, acute accent # etc ); %HTML_2_ASCII_7 = ( 'amp' => '&', # ampersand 'lt' => '<', # left chevron, less-than 'gt' => '>', # right chevron, greater-than 'quot' => '"', # double quote "Aacute" => "A" # capital A, acute accent # etc ); *HTML_Escapes = do { if ($standalone) { $PRETTY ? \%HTML_2_Latin_1 : \%HTML_2_ASCII_7; } else { \%HTML_2_Latin_1; } }; *THITHER = $standalone ? *STDOUT : *STDERR; $transmo = <) { #s/(.*)\n//; #$header = $1; unescape(); if ($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/[BC]<(.*?)>/bold($1)/ges; s/[LIF]<(.*?)>/italic($1)/ges; } else { s/[BC]<(.*?)>/$1/gs; s/[LIF]<(.*?)>/$1/gs; } unless (/^=/) { if (defined $header) { if ( $header eq 'DESCRIPTION' && ( /Optional warnings are enabled/ || /Some of these messages are generic./ ) ) { next; } s/^/ /gm; $msg{$header} .= $_; } next; } unless ( s/=item (.*)\s*\Z//) { if ( s/=head1\sDESCRIPTION//) { $msg{$header = 'DESCRIPTION'} = ''; } next; } # strip formatting directives in =item line ($header = $1) =~ s/[A-Z]<(.*?)>/$1/g; if ($header =~ /%[sd]/) { $rhs = $lhs = $header; #if ($lhs =~ s/(.*?)%d(?!%d)(.*)/\Q$1\E\\d+\Q$2\E\$/g) { if ($lhs =~ s/(.*?)%d(?!%d)(.*)/\Q$1\E\\d+\Q$2\E/g) { $lhs =~ s/\\%s/.*?/g; } else { # if i had lookbehind negations, i wouldn't have to do this \377 noise $lhs =~ s/(.*?)%s/\Q$1\E.*?\377/g; #$lhs =~ s/\377([^\377]*)$/\Q$1\E\$/; $lhs =~ s/\377([^\377]*)$/\Q$1\E/; $lhs =~ s/\377//g; $lhs =~ s/\.\*\?$/.*/; # Allow %s at the end to eat it all } $transmo .= " s{^$lhs}\n {\Q$rhs\E}s\n\t&& return 1;\n"; } else { $transmo .= " m{^\Q$header\E} && return 1;\n"; } print STDERR "$WHOAMI: Duplicate entry: \"$header\"\n" if $msg{$header}; $msg{$header} = ''; } close POD_DIAG unless *main::DATA eq *POD_DIAG; die "No diagnostics?" unless %msg; $transmo .= " return 0;\n}\n"; print STDERR $transmo if $DEBUG; eval $transmo; die $@ if $@; $RS = "\n"; ### } if ($standalone) { if (!@ARGV and -t STDIN) { print STDERR "$0: Reading from STDIN\n" } while (defined ($error = <>)) { splainthis($error) || print THITHER $error; } exit; } else { $old_w = 0; $oldwarn = ''; $olddie = ''; } sub import { shift; #$old_w = $^W; $^W = 1; # yup, clobbered the global variable; tough, if you # want diags, you want diags. return if $SIG{__WARN__} eq \&warn_trap; for (@_) { /^-d(ebug)?$/ && 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; }; warn "Unknown flag: $_"; } $oldwarn = $SIG{__WARN__}; $olddie = $SIG{__DIE__}; $SIG{__WARN__} = \&warn_trap; $SIG{__DIE__} = \&death_trap; } sub enable { &import } sub disable { shift; #$^W = $old_w; return unless $SIG{__WARN__} eq \&warn_trap; $SIG{__WARN__} = $oldwarn; $SIG{__DIE__} = $olddie; } sub warn_trap { my $warning = $_[0]; if (caller eq $WHOAMI or !splainthis($warning)) { print STDERR $warning; } &$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 (1) { my $caller = (caller($i++))[3] or last; if ($caller eq '(eval)') { $in_eval = 1; last; } } splainthis($exception) unless $in_eval; if (caller eq $WHOAMI) { print STDERR "INTERNAL EXCEPTION: $exception"; } &$olddie if defined $olddie and $olddie and $olddie ne \&death_trap; # We don't want to unset these if we're coming from an eval because # then we've turned off diagnostics. (Actually what does this next # line do? -PSeibel) $SIG{__DIE__} = $SIG{__WARN__} = '' unless $in_eval; local($Carp::CarpLevel) = 1; confess "Uncaught exception from user code:\n\t$exception"; # up we go; where we stop, nobody knows, but i think we die now # but i'm deeply afraid of the &$olddie guy reraising and us getting # into an indirect recursion loop }; sub splainthis { local $_ = shift; local $\; ### &finish_compilation unless %msg; s/\.?\n+$//; my $orig = $_; # return unless defined; s/, <.*?> (?:line|chunk).*$//; $real = s/(.*?) at .*? (?:line|chunk) \d+.*/$1/; s/^\((.*)\)$/$1/; if ($exact_duplicate{$orig}++) { return &transmo; } else { return 0 unless &transmo; } $orig = shorten($orig); if ($old_diag{$_}) { autodescribe(); print THITHER "$orig (#$old_diag{$_})\n"; $wantspace = 1; } else { autodescribe(); $old_diag{$_} = ++$count; print THITHER "\n" if $wantspace; $wantspace = 0; print THITHER "$orig (#$old_diag{$_})\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; } # have to do this: RS isn't set until run time, but we're executing at compiletime $RS = "\n"; 1 unless $standalone; # or it'll complain about itself __END__ # wish diag dbase were more accessible