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package Fatal; |
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|
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use 5.006_001; |
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use Carp; |
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use strict; |
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our($AUTOLOAD, $Debug, $VERSION); |
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|
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$VERSION = 1.03; |
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|
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$Debug = 0 unless defined $Debug; |
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|
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sub import { |
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my $self = shift(@_); |
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my($sym, $pkg); |
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my $void = 0; |
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$pkg = (caller)[0]; |
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foreach $sym (@_) { |
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if ($sym eq ":void") { |
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$void = 1; |
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} |
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else { |
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&_make_fatal($sym, $pkg, $void); |
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} |
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} |
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}; |
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|
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sub AUTOLOAD { |
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my $cmd = $AUTOLOAD; |
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$cmd =~ s/.*:://; |
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&_make_fatal($cmd, (caller)[0]); |
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goto &$AUTOLOAD; |
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} |
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|
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sub fill_protos { |
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my $proto = shift; |
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my ($n, $isref, @out, @out1, $seen_semi) = -1; |
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while ($proto =~ /\S/) { |
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$n++; |
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push(@out1,[$n,@out]) if $seen_semi; |
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push(@out, $1 . "{\$_[$n]}"), next if $proto =~ s/^\s*\\([\@%\$\&])//; |
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push(@out, "\$_[$n]"), next if $proto =~ s/^\s*([*\$&])//; |
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push(@out, "\@_[$n..\$#_]"), last if $proto =~ s/^\s*(;\s*)?\@//; |
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$seen_semi = 1, $n--, next if $proto =~ s/^\s*;//; # XXXX ???? |
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die "Unknown prototype letters: \"$proto\""; |
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} |
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push(@out1,[$n+1,@out]); |
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@out1; |
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} |
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|
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sub write_invocation { |
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my ($core, $call, $name, $void, @argvs) = @_; |
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if (@argvs == 1) { # No optional arguments |
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my @argv = @{$argvs[0]}; |
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shift @argv; |
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return "\t" . one_invocation($core, $call, $name, $void, @argv) . ";\n"; |
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} else { |
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my $else = "\t"; |
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my (@out, @argv, $n); |
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while (@argvs) { |
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@argv = @{shift @argvs}; |
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$n = shift @argv; |
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push @out, "$ {else}if (\@_ == $n) {\n"; |
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$else = "\t} els"; |
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push @out, |
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"\t\treturn " . one_invocation($core, $call, $name, $void, @argv) . ";\n"; |
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} |
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push @out, <<EOC; |
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} |
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die "$name(\@_): Do not expect to get ", scalar \@_, " arguments"; |
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EOC |
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return join '', @out; |
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} |
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} |
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|
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sub one_invocation { |
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my ($core, $call, $name, $void, @argv) = @_; |
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local $" = ', '; |
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if ($void) { |
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return qq/(defined wantarray)?$call(@argv): |
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$call(@argv) || croak "Can't $name(\@_)/ . |
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($core ? ': $!' : ', \$! is \"$!\"') . '"' |
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} else { |
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return qq{$call(@argv) || croak "Can't $name(\@_)} . |
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($core ? ': $!' : ', \$! is \"$!\"') . '"'; |
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} |
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} |
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|
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sub _make_fatal { |
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my($sub, $pkg, $void) = @_; |
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my($name, $code, $sref, $real_proto, $proto, $core, $call); |
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my $ini = $sub; |
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|
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$sub = "${pkg}::$sub" unless $sub =~ /::/; |
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$name = $sub; |
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$name =~ s/.*::// or $name =~ s/^&//; |
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print "# _make_fatal: sub=$sub pkg=$pkg name=$name void=$void\n" if $Debug; |
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croak "Bad subroutine name for Fatal: $name" unless $name =~ /^\w+$/; |
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if (defined(&$sub)) { # user subroutine |
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$sref = \&$sub; |
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$proto = prototype $sref; |
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$call = '&$sref'; |
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} elsif ($sub eq $ini) { # Stray user subroutine |
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die "$sub is not a Perl subroutine" |
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} else { # CORE subroutine |
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$proto = eval { prototype "CORE::$name" }; |
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die "$name is neither a builtin, nor a Perl subroutine" |
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if $@; |
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die "Cannot make a non-overridable builtin fatal" |
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if not defined $proto; |
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$core = 1; |
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$call = "CORE::$name"; |
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} |
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if (defined $proto) { |
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$real_proto = " ($proto)"; |
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} else { |
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$real_proto = ''; |
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$proto = '@'; |
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} |
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$code = <<EOS; |
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sub$real_proto { |
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local(\$", \$!) = (', ', 0); |
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EOS |
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my @protos = fill_protos($proto); |
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$code .= write_invocation($core, $call, $name, $void, @protos); |
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$code .= "}\n"; |
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print $code if $Debug; |
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{ |
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no strict 'refs'; # to avoid: Can't use string (...) as a symbol ref ... |
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$code = eval("package $pkg; use Carp; $code"); |
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die if $@; |
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no warnings; # to avoid: Subroutine foo redefined ... |
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*{$sub} = $code; |
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} |
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} |
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|
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1; |
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|
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__END__ |
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|
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=head1 NAME |
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|
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Fatal - replace functions with equivalents which succeed or die |
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|
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=head1 SYNOPSIS |
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|
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use Fatal qw(open close); |
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|
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sub juggle { . . . } |
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import Fatal 'juggle'; |
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|
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=head1 DESCRIPTION |
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|
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C<Fatal> provides a way to conveniently replace functions which normally |
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return a false value when they fail with equivalents which raise exceptions |
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if they are not successful. This lets you use these functions without |
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having to test their return values explicitly on each call. Exceptions |
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can be caught using C<eval{}>. See L<perlfunc> and L<perlvar> for details. |
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|
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The do-or-die equivalents are set up simply by calling Fatal's |
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C<import> routine, passing it the names of the functions to be |
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replaced. You may wrap both user-defined functions and overridable |
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CORE operators (except C<exec>, C<system> which cannot be expressed |
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via prototypes) in this way. |
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|
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If the symbol C<:void> appears in the import list, then functions |
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named later in that import list raise an exception only when |
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these are called in void context--that is, when their return |
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values are ignored. For example |
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|
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use Fatal qw/:void open close/; |
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|
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# properly checked, so no exception raised on error |
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if(open(FH, "< /bogotic") { |
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warn "bogo file, dude: $!"; |
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} |
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|
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# not checked, so error raises an exception |
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close FH; |
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|
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=head1 AUTHOR |
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|
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Lionel.Cons@cern.ch |
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|
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prototype updates by Ilya Zakharevich ilya@math.ohio-state.edu |
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|
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=cut |
