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diagnostics.pm
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1996-06-28
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#!/usr/local/bin/perl
eval 'exec perl -S $0 ${1+"$@"}'
if 0;
use Config;
if ($^O eq 'VMS') {
$diagnostics::PODFILE = VMS::Filespec::unixify($Config{'privlib'}) .
'/pod/perldiag.pod';
}
else { $diagnostics::PODFILE= $Config{privlib} . "/pod/perldiag.pod"; }
package diagnostics;
require 5.001;
use English;
use Carp;
=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<diagnostics> Pragma
This module extends the terse diagnostics normally emitted by both the
perl compiler and the perl interpeter, augmenting them wtih the more
explicative and endearing descriptions found in L<perldiag>. Like the
other pragmata, it affects to 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 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<perldiag> introduction before
any other diagnostics. The $diagnostics::PRETTY can generate nicer escape
sequences for pgers.
=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 theorectical
(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 diagnostic::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 to 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 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<E<lt>tchrist@mox.perl.comE<gt>>, 25 June 1995.
=cut
$DEBUG ||= 0;
my $WHOAMI = ref bless []; # nobody's business, prolly not even mine
$OUTPUT_AUTOFLUSH = 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:') || 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 (<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 $0";
}
%HTML_2_Troff = (
'amp' => '&', # ampersand
'lt' => '<', # left chevron, less-than
'gt' => '>', # right chevron, greater-than
'quot' => '"', # double quote
"Aacute" => "A\\*'", # capital A, acute accent
# etc
);
%HTML_2_Latin_1 = (
'amp' => '&', # ampersand
'lt' => '<', # left chevron, less-than
'gt' => '>', # right chevron, greater-than
'quot' => '"', # double quote
"Aacute" => "\xC1" # capital A, acute accent
# etc
);
%HTML_2_ASCII_7 = (
'amp' => '&', # ampersand
'lt' => '<', # left chevron, less-than
'gt' => '>', # right chevron, greater-than
'quot' => '"', # double quote
"Aacute" => "A" # capital A, acute accent
# etc
);
*HTML_Escapes = do {
if ($standalone) {
$PRETTY ? \%HTML_2_Latin_1 : \%HTML_2_ASCII_7;
} else {
\%HTML_2_Latin_1;
}
};
*THITHER = $standalone ? *STDOUT : *STDERR;
$transmo = <<EOFUNC;
sub transmo {
local \$^W = 0; # recursive warnings we do NOT need!
study;
EOFUNC
### sub finish_compilation { # 5.001e panic: top_level for embedded version
print STDERR "FINISHING COMPILATION for $_\n" if $DEBUG;
### local
$RS = '';
local $_;
while (<POD_DIAG>) {
#s/(.*)\n//;
#$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