git-flavoured autodie 1.997 patch

G'day p5p,

Since we've moved over to git, attached is a git-friendly patch of autodie
1.997 against the current blead.  It's no different to the older 1.997
patch[1], but contains all the meta-info that git likes to have so that you
can use 'git am' to apply the changes.

All the very best,

	Paul

[1] Okay, there's one or two non-significant whitespace changes.

--
Paul Fenwick <pjf@perltraining.com.au> | http://perltraining.com.au/
Director of Training                   | Ph:  +61 3 9354 6001
Perl Training Australia                | Fax: +61 3 9354 2681

>From b0dc5ff6b006a9df2a67b886e5e0d0d168c1245e Mon Sep 17 00:00:00 2001
From: Paul Fenwick <pjf@perltraining.com.au>
Date: Sun, 21 Dec 2008 00:17:28 +1100
Subject: [PATCH] Autodie 1.997

1 files changed, 1041 insertions, 118 deletions

diff --git a/lib/Fatal.pm b/lib/Fatal.pm
index 0b4bf9bc99..0f7ef8f124 100644
--- a/lib/Fatal.pm
+++ b/lib/Fatal.pm
@@ -1,193 +1,1116 @@
 package Fatal;
 
-use 5.006_001;
+use 5.008;  # 5.8.x needed for autodie
 use Carp;
 use strict;
-our($AUTOLOAD, $Debug, $VERSION);
+use warnings;
 
-$VERSION = 1.06;
+use constant LEXICAL_TAG => q{:lexical};
+use constant VOID_TAG    => q{:void};
 
-$Debug = 0 unless defined $Debug;
+use constant ERROR_NOARGS    => 'Cannot use lexical %s with no arguments';
+use constant ERROR_VOID_LEX  => VOID_TAG.' cannot be used with lexical scope';
+use constant ERROR_LEX_FIRST => LEXICAL_TAG.' must be used as first argument';
+use constant ERROR_NO_LEX    => "no %s can only start with ".LEXICAL_TAG;
+use constant ERROR_BADNAME   => "Bad subroutine name for %s: %s";
+use constant ERROR_NOTSUB    => "%s is not a Perl subroutine";
+use constant ERROR_NOT_BUILT => "%s is neither a builtin, nor a Perl subroutine";
+use constant ERROR_CANT_OVERRIDE => "Cannot make the non-overridable builtin %s fatal";
+
+use constant ERROR_NO_IPC_SYS_SIMPLE => "IPC::System::Simple required for Fatalised/autodying system()";
+
+use constant ERROR_IPC_SYS_SIMPLE_OLD => "IPC::System::Simple version %f required for Fatalised/autodying system().  We only have version %f";
+
+use constant ERROR_AUTODIE_CONFLICT => q{"no autodie '%s'" is not allowed while "use Fatal '%s'" is in effect};
+
+use constant ERROR_FATAL_CONFLICT => q{"use Fatal '%s'" is not allowed while "no autodie '%s'" is in effect};
+
+# Older versions of IPC::System::Simple don't support all the
+# features we need.
+
+use constant MIN_IPC_SYS_SIMPLE_VER => 0.12;
+
+# All the Fatal/autodie modules share the same version number.
+our $VERSION = '1.997';
+
+our $Debug ||= 0;
+
+# EWOULDBLOCK values for systems that don't supply their own.
+# Even though this is defined with our, that's to help our
+# test code.  Please don't rely upon this variable existing in
+# the future.
+
+our %_EWOULDBLOCK = (
+    MSWin32 => 33,
+);
+
+# We have some tags that can be passed in for use with import.
+# These are all assumed to be CORE::
+
+my %TAGS = (
+    ':io'      => [qw(:dbm :file :filesys :ipc :socket
+                       read seek sysread syswrite sysseek )],
+    ':dbm'     => [qw(dbmopen dbmclose)],
+    ':file'    => [qw(open close flock sysopen fcntl fileno binmode
+                     ioctl truncate)],
+    ':filesys' => [qw(opendir closedir chdir link unlink rename mkdir
+                      symlink rmdir readlink umask)],
+    ':ipc'     => [qw(:msg :semaphore :shm pipe)],
+    ':msg'     => [qw(msgctl msgget msgrcv msgsnd)],
+    ':threads' => [qw(fork)],
+    ':semaphore'=>[qw(semctl semget semop)],
+    ':shm'     => [qw(shmctl shmget shmread)],
+    ':system'  => [qw(system exec)],
+
+    # Can we use qw(getpeername getsockname)? What do they do on failure?
+    # XXX - Can socket return false?
+    ':socket'  => [qw(accept bind connect getsockopt listen recv send
+                   setsockopt shutdown socketpair)],
+
+    # Our defaults don't include system(), because it depends upon
+    # an optional module, and it breaks the exotic form.
+    #
+    # This *may* change in the future.  I'd love IPC::System::Simple
+    # to be a dependency rather than a recommendation, and hence for
+    # system() to be autodying by default.
+
+    ':default' => [qw(:io :threads)],
+
+    # Version specific tags.  These allow someone to specify
+    # use autodie qw(:1.994) and know exactly what they'll get.
+
+    ':1.994' => [qw(:default)],
+    ':1.995' => [qw(:default)],
+    ':1.996' => [qw(:default)],
+    ':1.997' => [qw(:default)],
+
+);
+
+$TAGS{':all'}  = [ keys %TAGS ];
+
+# This hash contains subroutines for which we should
+# subroutine() // die() rather than subroutine() || die()
+
+my %Use_defined_or;
+
+# CORE::open returns undef on failure.  It can legitimately return
+# 0 on success, eg: open(my $fh, '-|') || exec(...);
+
+@Use_defined_or{qw(
+    CORE::fork
+    CORE::recv
+    CORE::send
+    CORE::open
+    CORE::fileno
+    CORE::read
+    CORE::readlink
+    CORE::sysread
+    CORE::syswrite
+    CORE::sysseek
+    CORE::umask
+)} = ();
+
+# Cached_fatalised_sub caches the various versions of our
+# fatalised subs as they're produced.  This means we don't
+# have to build our own replacement of CORE::open and friends
+# for every single package that wants to use them.
+
+my %Cached_fatalised_sub = ();
+
+# Every time we're called with package scope, we record the subroutine
+# (including package or CORE::) in %Package_Fatal.  This allows us
+# to detect illegal combinations of autodie and Fatal, and makes sure
+# we don't accidently make a Fatal function autodying (which isn't
+# very useful).
+
+my %Package_Fatal = ();
+
+# The first time we're called with a user-sub, we cache it here.
+# In the case of a "no autodie ..." we put back the cached copy.
+
+my %Original_user_sub = ();
+
+# We use our package in a few hash-keys.  Having it in a scalar is
+# convenient.  The "guard $PACKAGE" string is used as a key when
+# setting up lexical guards.
+
+my $PACKAGE       = __PACKAGE__;
+my $PACKAGE_GUARD = "guard $PACKAGE";
+my $NO_PACKAGE    = "no $PACKAGE";      # Used to detect 'no autodie'
+
+# Here's where all the magic happens when someone write 'use Fatal'
+# or 'use autodie'.
 
 sub import {
-    my $self = shift(@_);
-    my($sym, $pkg);
-    my $void = 0;
-    $pkg = (caller)[0];
-    foreach $sym (@_) {
-	if ($sym eq ":void") {
-	    $void = 1;
-	}
-	else {
-	    &_make_fatal($sym, $pkg, $void);
-	}
-    }
-};
-
-sub AUTOLOAD {
-    my $cmd = $AUTOLOAD;
-    $cmd =~ s/.*:://;
-    &_make_fatal($cmd, (caller)[0]);
-    goto &$AUTOLOAD;
+    my $class   = shift(@_);
+    my $void    = 0;
+    my $lexical = 0;
+
+    my ($pkg, $filename) = caller();
+
+    @_ or return;   # 'use Fatal' is a no-op.
+
+    # If we see the :lexical flag, then _all_ arguments are
+    # changed lexically
+
+    if ($_[0] eq LEXICAL_TAG) {
+        $lexical = 1;
+        shift @_;
+
+        # If we see no arguments and :lexical, we assume they
+        # wanted ':default'.
+
+        if (@_ == 0) {
+            push(@_, ':default');
+        }
+
+        # Don't allow :lexical with :void, it's needlessly confusing.
+        if ( grep { $_ eq VOID_TAG } @_ ) {
+            croak(ERROR_VOID_LEX);
+        }
+    }
+
+    if ( grep { $_ eq LEXICAL_TAG } @_ ) {
+        # If we see the lexical tag as the non-first argument, complain.
+        croak(ERROR_LEX_FIRST);
+    }
+
+    my @fatalise_these =  @_;
+
+    # Thiese subs will get unloaded at the end of lexical scope.
+    my %unload_later;
+
+    # This hash helps us track if we've alredy done work.
+    my %done_this;
+
+    # NB: we're using while/shift rather than foreach, since
+    # we'll be modifying the array as we walk through it.
+
+    while (my $func = shift @fatalise_these) {
+
+        if ($func eq VOID_TAG) {
+
+            # When we see :void, set the void flag.
+            $void = 1;
+
+        } elsif (exists $TAGS{$func}) {
+
+            # When it's a tag, expand it.
+            push(@fatalise_these, @{ $TAGS{$func} });
+
+        } else {
+
+            # Otherwise, fatalise it.
+
+            # If we've already made something fatal this call,
+            # then don't do it twice.
+
+            next if $done_this{$func};
+
+            # We're going to make a subroutine fatalistic.
+            # However if we're being invoked with 'use Fatal qw(x)'
+            # and we've already been called with 'no autodie qw(x)'
+            # in the same scope, we consider this to be an error.
+            # Mixing Fatal and autodie effects was considered to be
+            # needlessly confusing on p5p.
+
+            my $sub = $func;
+            $sub = "${pkg}::$sub" unless $sub =~ /::/;
+
+            # If we're being called as Fatal, and we've previously
+            # had a 'no X' in scope for the subroutine, then complain
+            # bitterly.
+
+            if (! $lexical and $^H{$NO_PACKAGE}{$sub}) {
+                 croak(sprintf(ERROR_FATAL_CONFLICT, $func, $func));
+            }
+
+            # We're not being used in a confusing way, so make
+            # the sub fatal.  Note that _make_fatal returns the
+            # old (original) version of the sub, or undef for
+            # built-ins.
+
+            my $sub_ref = $class->_make_fatal(
+                $func, $pkg, $void, $lexical, $filename
+            );
+
+            $done_this{$func}++;
+
+            $Original_user_sub{$sub} ||= $sub_ref;
+
+            # If we're making lexical changes, we need to arrange
+            # for them to be cleaned at the end of our scope, so
+            # record them here.
+
+            $unload_later{$func} = $sub_ref if $lexical;
+        }
+    }
+
+    if ($lexical) {
+
+        # Dark magic to have autodie work under 5.8
+        # Copied from namespace::clean, that copied it from
+        # autobox, that found it on an ancient scroll written
+        # in blood.
+
+        # This magic bit causes %^H to be lexically scoped.
+
+        $^H |= 0x020000;
+
+        # Our package guard gets invoked when we leave our lexical
+        # scope.
+
+        push(@ { $^H{$PACKAGE_GUARD} }, autodie::Scope::Guard->new(sub {
+            $class->_install_subs($pkg, \%unload_later);
+        }));
+
+    }
+
+    return;
+
+}
+
+# The code here is originally lifted from namespace::clean,
+# by Robert "phaylon" Sedlacek.
+#
+# It's been redesigned after feedback from ikegami on perlmonks.
+# See http://perlmonks.org/?node_id=693338 .  Ikegami rocks.
+#
+# Given a package, and hash of (subname => subref) pairs,
+# we install the given subroutines into the package.  If
+# a subref is undef, the subroutine is removed.  Otherwise
+# it replaces any existing subs which were already there.
+
+sub _install_subs {
+    my ($class, $pkg, $subs_to_reinstate) = @_;
+
+    my $pkg_sym = "${pkg}::";
+
+    while(my ($sub_name, $sub_ref) = each %$subs_to_reinstate) {
+
+        my $full_path = $pkg_sym.$sub_name;
+
+        # Copy symbols across to temp area.
+
+        no strict 'refs';   ## no critic
+
+        local *__tmp = *{ $full_path };
+
+        # Nuke the old glob.
+        { no strict; delete $pkg_sym->{$sub_name}; }    ## no critic
+
+        # Copy innocent bystanders back.
+
+        foreach my $slot (qw( SCALAR ARRAY HASH IO FORMAT ) ) {
+            next unless defined *__tmp{ $slot };
+            *{ $full_path } = *__tmp{ $slot };
+        }
+
+        # Put back the old sub (if there was one).
+
+        if ($sub_ref) {
+
+            no strict;  ## no critic
+            *{ $pkg_sym . $sub_name } = $sub_ref;
+        }
+    }
+
+    return;
+}
+
+sub unimport {
+    my $class = shift;
+
+    # Calling "no Fatal" must start with ":lexical"
+    if ($_[0] ne LEXICAL_TAG) {
+        croak(sprintf(ERROR_NO_LEX,$class));
+    }
+
+    shift @_;   # Remove :lexical
+
+    my $pkg = (caller)[0];
+
+    # If we've been called with arguments, then the developer
+    # has explicitly stated 'no autodie qw(blah)',
+    # in which case, we disable Fatalistic behaviour for 'blah'.
+
+    my @unimport_these = @_ ? @_ : ':all';
+
+    while (my $symbol = shift @unimport_these) {
+
+        if ($symbol =~ /^:/) {
+
+            # Looks like a tag!  Expand it!
+            push(@unimport_these, @{ $TAGS{$symbol} });
+
+            next;
+        }
+
+        my $sub = $symbol;
+        $sub = "${pkg}::$sub" unless $sub =~ /::/;
+
+        # If 'blah' was already enabled with Fatal (which has package
+        # scope) then, this is considered an error.
+
+        if (exists $Package_Fatal{$sub}) {
+            croak(sprintf(ERROR_AUTODIE_CONFLICT,$symbol,$symbol));
+        }
+
+        # Record 'no autodie qw($sub)' as being in effect.
+        # This is to catch conflicting semantics elsewhere
+        # (eg, mixing Fatal with no autodie)
+
+        $^H{$NO_PACKAGE}{$sub} = 1;
+
+        if (my $original_sub = $Original_user_sub{$sub}) {
+            # Hey, we've got an original one of these, put it back.
+            $class->_install_subs($pkg, { $symbol => $original_sub });
+            next;
+        }
+
+        # We don't have an original copy of the sub, on the assumption
+        # it's core (or doesn't exist), we'll just nuke it.
+
+        $class->_install_subs($pkg,{ $symbol => undef });
+
+    }
+
+    return;
+
+}
+
+# TODO - This is rather terribly inefficient right now.
+
+# NB: Perl::Critic's dump-autodie-tag-contents depends upon this
+# continuing to work.
+
+{
+    my %tag_cache;
+
+    sub _expand_tag {
+        my ($class, $tag) = @_;
+
+        if (my $cached = $tag_cache{$tag}) {
+            return $cached;
+        }
+
+        if (not exists $TAGS{$tag}) {
+            croak "Invalid exception class $tag";
+        }
+
+        my @to_process = @{$TAGS{$tag}};
+
+        my @taglist = ();
+
+        while (my $item = shift @to_process) {
+            if ($item =~ /^:/) {
+                push(@to_process, @{$TAGS{$item}} );
+            } else {
+                push(@taglist, "CORE::$item");
+            }
+        }
+
+        $tag_cache{$tag} = \@taglist;
+
+        return \@taglist;
+
+    }
+
 }
 
+# This code is from the original Fatal.  It scares me.
+
 sub fill_protos {
-  my $proto = shift;
-  my ($n, $isref, @out, @out1, $seen_semi) = -1;
-  while ($proto =~ /\S/) {
-    $n++;
-    push(@out1,[$n,@out]) if $seen_semi;
-    push(@out, $1 . "{\$_[$n]}"), next if $proto =~ s/^\s*\\([\@%\$\&])//;
-    push(@out, "\$_[$n]"), next if $proto =~ s/^\s*([_*\$&])//;
-    push(@out, "\@_[$n..\$#_]"), last if $proto =~ s/^\s*(;\s*)?\@//;
-    $seen_semi = 1, $n--, next if $proto =~ s/^\s*;//; # XXXX ????
-    die "Unknown prototype letters: \"$proto\"";
-  }
-  push(@out1,[$n+1,@out]);
-  @out1;
+    my $proto = shift;
+    my ($n, $isref, @out, @out1, $seen_semi) = -1;
+    while ($proto =~ /\S/) {
+        $n++;
+        push(@out1,[$n,@out]) if $seen_semi;
+        push(@out, $1 . "{\$_[$n]}"), next if $proto =~ s/^\s*\\([\@%\$\&])//;
+        push(@out, "\$_[$n]"),        next if $proto =~ s/^\s*([_*\$&])//;
+        push(@out, "\@_[$n..\$#_]"),  last if $proto =~ s/^\s*(;\s*)?\@//;
+        $seen_semi = 1, $n--,         next if $proto =~ s/^\s*;//; # XXXX ????
+        die "Internal error: Unknown prototype letters: \"$proto\"";
+    }
+    push(@out1,[$n+1,@out]);
+    return @out1;
 }
 
+# This generates the code that will become our fatalised subroutine.
+
 sub write_invocation {
-  my ($core, $call, $name, $void, @argvs) = @_;
-  if (@argvs == 1) {		# No optional arguments
-    my @argv = @{$argvs[0]};
-    shift @argv;
-    return "\t" . one_invocation($core, $call, $name, $void, @argv) . ";\n";
-  } else {
-    my $else = "\t";
-    my (@out, @argv, $n);
-    while (@argvs) {
-      @argv = @{shift @argvs};
-      $n = shift @argv;
-      push @out, "$ {else}if (\@_ == $n) {\n";
-      $else = "\t} els";
-      push @out, 
-          "\t\treturn " . one_invocation($core, $call, $name, $void, @argv) . ";\n";
-    }
-    push @out, <<EOC;
-	}
-	die "$name(\@_): Do not expect to get ", scalar \@_, " arguments";
-EOC
-    return join '', @out;
-  }
+    my ($class, $core, $call, $name, $void, $lexical, $sub, @argvs) = @_;
+
+    if (@argvs == 1) {        # No optional arguments
+
+        my @argv = @{$argvs[0]};
+        shift @argv;
+
+        return $class->one_invocation($core,$call,$name,$void,$sub,! $lexical,@argv);
+
+    } else {
+        my $else = "\t";
+        my (@out, @argv, $n);
+        while (@argvs) {
+            @argv = @{shift @argvs};
+            $n = shift @argv;
+
+            push @out, "${else}if (\@_ == $n) {\n";
+            $else = "\t} els";
+
+        push @out, $class->one_invocation($core,$call,$name,$void,$sub,! $lexical,@argv);
+        }
+        push @out, q[
+            }
+            die "Internal error: $name(\@_): Do not expect to get ", scalar \@_, " arguments";
+    ];
+
+        return join '', @out;
+    }
 }
 
 sub one_invocation {
-  my ($core, $call, $name, $void, @argv) = @_;
-  local $" = ', ';
-  if ($void) { 
-    return qq/(defined wantarray)?$call(@argv):
-              $call(@argv) || croak "Can't $name(\@_)/ . 
-           ($core ? ': $!' : ', \$! is \"$!\"') . '"'
-  } else {
-    return qq{$call(@argv) || croak "Can't $name(\@_)} . 
-           ($core ? ': $!' : ', \$! is \"$!\"') . '"';
-  }
+    my ($class, $core, $call, $name, $void, $sub, $back_compat, @argv) = @_;
+
+    # If someone is calling us directly (a child class perhaps?) then
+    # they could try to mix void without enabling backwards
+    # compatibility.  We just don't support this at all, so we gripe
+    # about it rather than doing something unwise.
+
+    if ($void and not $back_compat) {
+        Carp::confess("Internal error: :void mode not supported with $class");
+    }
+
+    # @argv only contains the results of the in-built prototype
+    # function, and is therefore safe to interpolate in the
+    # code generators below.
+
+    # TODO - The following clobbers context, but that's what the
+    #        old Fatal did.  Do we care?
+
+    if ($back_compat) {
+
+        # TODO - Use Fatal qw(system) is not yet supported.  It should be!
+
+        if ($call eq 'CORE::system') {
+            return q{
+                croak("UNIMPLEMENTED: use Fatal qw(system) not yet supported.");
+            };
+        }
+
+        local $" = ', ';
+
+        if ($void) {
+            return qq/return (defined wantarray)?$call(@argv):
+                   $call(@argv) || croak "Can't $name(\@_)/ .
+                   ($core ? ': $!' : ', \$! is \"$!\"') . '"'
+        } else {
+            return qq{return $call(@argv) || croak "Can't $name(\@_)} .
+                   ($core ? ': $!' : ', \$! is \"$!\"') . '"';
+        }
+    }
+
+    # The name of our original function is:
+    #   $call if the function is CORE
+    #   $sub if our function is non-CORE
+
+    # The reason for this is that $call is what we're actualling
+    # calling.  For our core functions, this is always
+    # CORE::something.  However for user-defined subs, we're about to
+    # replace whatever it is that we're calling; as such, we actually
+    # calling a subroutine ref.
+
+    # Unfortunately, none of this tells us the *ultimate* name.
+    # For example, if I export 'copy' from File::Copy, I'd like my
+    # ultimate name to be File::Copy::copy.
+    #
+    # TODO - Is there any way to find the ultimate name of a sub, as
+    # described above?
+
+    my $true_sub_name = $core ? $call : $sub;
+
+    if ($call eq 'CORE::system') {
+
+        # Leverage IPC::System::Simple if we're making an autodying
+        # system.
+
+        local $" = ", ";
+
+        # We need to stash $@ into $E, rather than using
+        # local $@ for the whole sub.  If we don't then
+        # any exceptions from internal errors in autodie/Fatal
+        # will mysteriously disappear before propogating
+        # upwards.
+
+        return qq{
+            my \$retval;
+            my \$E;
+
+
+            {
+                local \$@;
+
+                eval {
+                    \$retval = IPC::System::Simple::system(@argv);
+                };
+
+                \$E = \$@;
+            }
+
+            if (\$E) {
+
+                # XXX - TODO - This can't be overridden in child
+                # classes!
+
+                die autodie::exception::system->new(
+                    function => q{CORE::system}, args => [ @argv ],
+                    message => "\$E", errno => \$!,
+                );
+            }
+
+            return \$retval;
+        };
+
+    }
+
+    # Should we be testing to see if our result is defined, or
+    # just true?
+    my $use_defined_or = exists ( $Use_defined_or{$call} );
+
+    local $" = ', ';
+
+    # If we're going to throw an exception, here's the code to use.
+    my $die = qq{
+        die $class->throw(
+            function => q{$true_sub_name}, args => [ @argv ],
+            pragma => q{$class}, errno => \$!,
+        )
+    };
+
+    if ($call eq 'CORE::flock') {
+
+        # flock needs special treatment.  When it fails with
+        # LOCK_UN and EWOULDBLOCK, then it's not really fatal, it just
+        # means we couldn't get the lock right now.
+
+        require POSIX;      # For POSIX::EWOULDBLOCK
+
+        local $@;   # Don't blat anyone else's $@.
+
+        # Ensure that our vendor supports EWOULDBLOCK.  If they
+        # don't (eg, Windows), then we use known values for its
+        # equivalent on other systems.
+
+        my $EWOULDBLOCK = eval { POSIX::EWOULDBLOCK(); }
+                          || $_EWOULDBLOCK{$^O}
+                          || _autocroak("Internal error - can't overload flock - EWOULDBLOCK not defined on this system.");
+
+        require Fcntl;      # For Fcntl::LOCK_NB
+
+        return qq{
+
+            # Try to flock.  If successful, return it immediately.
+
+            my \$retval = $call(@argv);
+            return \$retval if \$retval;
+
+            # If we failed, but we're using LOCK_NB and
+            # returned EWOULDBLOCK, it's not a real error.
+
+            if (\$_[1] & Fcntl::LOCK_NB() and \$! == $EWOULDBLOCK ) {
+                return \$retval;
+            }
+
+            # Otherwise, we failed.  Die noisily.
+
+            $die;
+
+        };
+    }
+
+    # AFAIK everything that can be given an unopned filehandle
+    # will fail if it tries to use it, so we don't really need
+    # the 'unopened' warning class here.  Especially since they
+    # then report the wrong line number.
+
+    return qq{
+        no warnings qw(unopened);
+
+        if (wantarray) {
+            my \@results = $call(@argv);
+            # If we got back nothing, or we got back a single
+            # undef, we die.
+            if (! \@results or (\@results == 1 and ! defined \$results[0])) {
+                $die;
+            };
+            return \@results;
+        }
+
+        # Otherwise, we're in scalar context.
+        # We're never in a void context, since we have to look
+        # at the result.
+
+        my \$result = $call(@argv);
+
+    } . ( $use_defined_or ? qq{
+
+        $die if not defined \$result;
+
+        return \$result;
+
+    } : qq{
+
+        return \$result || $die;
+
+    } ) ;
+
 }
 
+# This returns the old copy of the sub, so we can
+# put it back at end of scope.
+
+# TODO : Check to make sure prototypes are restored correctly.
+
+# TODO: Taking a huge list of arguments is awful.  Rewriting to
+#       take a hash would be lovely.
+
 sub _make_fatal {
-    my($sub, $pkg, $void) = @_;
+    my($class, $sub, $pkg, $void, $lexical, $filename) = @_;
     my($name, $code, $sref, $real_proto, $proto, $core, $call);
     my $ini = $sub;
 
     $sub = "${pkg}::$sub" unless $sub =~ /::/;
+
+    # Figure if we're using lexical or package semantics and
+    # twiddle the appropriate bits.
+
+    if (not $lexical) {
+        $Package_Fatal{$sub} = 1;
+    }
+
+    # TODO - We *should* be able to do skipping, since we know when
+    # we've lexicalised / unlexicalised a subroutine.
+
     $name = $sub;
     $name =~ s/.*::// or $name =~ s/^&//;
-    print "# _make_fatal: sub=$sub pkg=$pkg name=$name void=$void\n" if $Debug;
-    croak "Bad subroutine name for Fatal: $name" unless $name =~ /^\w+$/;
-    if (defined(&$sub)) {	# user subroutine
-	$sref = \&$sub;
-	$proto = prototype $sref;
-	$call = '&$sref';
+
+    warn  "# _make_fatal: sub=$sub pkg=$pkg name=$name void=$void\n" if $Debug;
+    croak(sprintf(ERROR_BADNAME, $class, $name)) unless $name =~ /^\w+$/;
+
+    if (defined(&$sub)) {   # user subroutine
+
+        # This could be something that we've fatalised that
+        # was in core.
+
+        local $@; # Don't clobber anyone else's $@
+
+        if ( $Package_Fatal{$sub} and eval { prototype "CORE::$name" } ) {
+
+            # Something we previously made Fatal that was core.
+            # This is safe to replace with an autodying to core
+            # version.
+
+            $core  = 1;
+            $call  = "CORE::$name";
+            $proto = prototype $call;
+
+            # We return our $sref from this subroutine later
+            # on, indicating this subroutine should be placed
+            # back when we're finished.
+
+            $sref = \&$sub;
+
+        } else {
+
+            # A regular user sub, or a user sub wrapping a
+            # core sub.
+
+            $sref = \&$sub;
+            $proto = prototype $sref;
+            $call = '&$sref';
+
+        }
+
     } elsif ($sub eq $ini && $sub !~ /^CORE::GLOBAL::/) {
-	# Stray user subroutine
-	die "$sub is not a Perl subroutine" 
-    } else {			# CORE subroutine
+        # Stray user subroutine
+        croak(sprintf(ERROR_NOTSUB,$sub));
+
+    } elsif ($name eq 'system') {
+
+        # If we're fatalising system, then we need to load
+        # helper code.
+
+        eval {
+            require IPC::System::Simple; # Only load it if we need it.
+            require autodie::exception::system;
+        };
+
+        if ($@) { croak ERROR_NO_IPC_SYS_SIMPLE; }
+
+            # Make sure we're using a recent version of ISS that actually
+            # support fatalised system.
+            if ($IPC::System::Simple::VERSION < MIN_IPC_SYS_SIMPLE_VER) {
+                croak sprintf(
+                ERROR_IPC_SYS_SIMPLE_OLD, MIN_IPC_SYS_SIMPLE_VER,
+                $IPC::System::Simple::VERSION
+                );
+            }
+
+        $call = 'CORE::system';
+        $name = 'system';
+
+    } elsif ($name eq 'exec') {
+        # Exec doesn't have a prototype.  We don't care.  This
+        # breaks the exotic form with lexical scope, and gives
+        # the regular form a "do or die" beaviour as expected.
+
+        $call = 'CORE::exec';
+        $name = 'exec';
+        $core = 1;
+
+    } else {            # CORE subroutine
         $proto = eval { prototype "CORE::$name" };
-	die "$name is neither a builtin, nor a Perl subroutine" 
-	  if $@;
-	die "Cannot make the non-overridable builtin $name fatal"
-	  if not defined $proto;
-	$core = 1;
-	$call = "CORE::$name";
+        croak(sprintf(ERROR_NOT_BUILT,$name)) if $@;
+        croak(sprintf(ERROR_CANT_OVERRIDE,$name)) if not defined $proto;
+        $core = 1;
+        $call = "CORE::$name";
     }
+
     if (defined $proto) {
-      $real_proto = " ($proto)";
+        $real_proto = " ($proto)";
     } else {
-      $real_proto = '';
-      $proto = '@';
+        $real_proto = '';
+        $proto = '@';
+    }
+
+    my $true_name = $core ? $call : $sub;
+
+    # TODO: This caching works, but I don't like using $void and
+    # $lexical as keys.  In particular, I suspect our code may end up
+    # wrapping already wrapped code when autodie and Fatal are used
+    # together.
+
+    # NB: We must use '$sub' (the name plus package) and not
+    # just '$name' (the short name) here.  Failing to do so
+    # results code that's in the wrong package, and hence has
+    # access to the wrong package filehandles.
+
+    if (my $subref = $Cached_fatalised_sub{$class}{$sub}{$void}{$lexical}) {
+        $class->_install_subs($pkg, { $name => $subref });
+        return $sref;
     }
-    $code = <<EOS;
-sub$real_proto {
-	local(\$", \$!) = (', ', 0);
-EOS
+
+    $code = qq[
+        sub$real_proto {
+            local(\$", \$!) = (', ', 0);    # TODO - Why do we do this?
+    ];
+
+    # Don't have perl whine if exec fails, since we'll be handling
+    # the exception now.
+    $code .= "no warnings qw(exec);\n" if $call eq "CORE::exec";
+
     my @protos = fill_protos($proto);
-    $code .= write_invocation($core, $call, $name, $void, @protos);
+    $code .= $class->write_invocation($core, $call, $name, $void, $lexical, $sub, @protos);
     $code .= "}\n";
-    print $code if $Debug;
+    warn $code if $Debug;
+
+    # I thought that changing package was a monumental waste of
+    # time for CORE subs, since they'll always be the same.  However
+    # that's not the case, since they may refer to package-based
+    # filehandles (eg, with open).
+    #
+    # There is potential to more aggressively cache core subs
+    # that we know will never want to interact with package variables
+    # and filehandles.
+
     {
-      no strict 'refs'; # to avoid: Can't use string (...) as a symbol ref ...
-      $code = eval("package $pkg; use Carp; $code");
-      die if $@;
-      no warnings;   # to avoid: Subroutine foo redefined ...
-      *{$sub} = $code;
+        local $@;
+        no strict 'refs'; ## no critic # to avoid: Can't use string (...) as a symbol ref ...
+        $code = eval("package $pkg; use Carp; $code");  ## no critic
+        if (not $code) {
+
+            # For some reason, using a die, croak, or confess in here
+            # results in the error being completely surpressed. As such,
+            # we need to do our own reporting.
+            #
+            # TODO: Fix the above.
+
+            _autocroak("Internal error in autodie/Fatal processing $true_name: $@");
+
+        }
+    }
+
+    # Now we need to wrap our fatalised sub inside an itty bitty
+    # closure, which can detect if we've leaked into another file.
+    # Luckily, we only need to do this for lexical (autodie)
+    # subs.  Fatal subs can leak all they want, it's considered
+    # a "feature" (or at least backwards compatible).
+
+    # TODO: Cache our leak guards!
+
+    # TODO: This is pretty hairy code.  A lot more tests would
+    # be really nice for this.
+
+    my $leak_guard;
+
+    if ($lexical) {
+
+        $leak_guard = qq<
+            package $pkg;
+
+            sub$real_proto {
+
+                # If we're called from the correct file, then use the
+                # autodying code.
+                goto &\$code if ((caller)[1] eq \$filename);
+
+                # Oh bother, we've leaked into another file.  Call the
+                # original code.  Note that \$sref may actually be a
+                # reference to a Fatalised version of a core built-in.
+                # That's okay, because Fatal *always* leaks between files.
+
+                goto &\$sref if \$sref;
+        >;
+
+
+        # If we're here, it must have been a core subroutine called.
+        # Warning: The following code may disturb some viewers.
+
+        # TODO: It should be possible to combine this with
+        # write_invocation().
+
+        foreach my $proto (@protos) {
+            local $" = ", ";    # So @args is formatted correctly.
+            my ($count, @args) = @$proto;
+            $leak_guard .= qq<
+                if (\@_ == $count) {
+                    return $call(@args);
+                }
+            >;
+        }
+
+        $leak_guard .= qq< croak "Internal error in Fatal/autodie.  Leak-guard failure"; } >;
+
+        # warn "$leak_guard\n";
+
+        local $@;
+
+        $leak_guard = eval $leak_guard;  ## no critic
+
+        die "Internal error in $class: Leak-guard installation failure: $@" if $@;
+    }
+
+    $class->_install_subs($pkg, { $name => $leak_guard || $code });
+
+    $Cached_fatalised_sub{$class}{$sub}{$void}{$lexical} = $leak_guard || $code;
+
+    return $sref;
+
+}
+
+# This subroutine exists primarily so that child classes can override
+# it to point to their own exception class.  Doing this is significantly
+# less complex than overriding throw()
+
+sub exception_class { return "autodie::exception" };
+
+{
+    my %exception_class_for;
+    my %class_loaded;
+
+    sub throw {
+        my ($class, @args) = @_;
+
+        # Find our exception class if we need it.
+        my $exception_class =
+             $exception_class_for{$class} ||= $class->exception_class;
+
+        if (not $class_loaded{$exception_class}) {
+            if ($exception_class =~ /[^\w:']/) {
+                confess "Bad exception class '$exception_class'.\nThe '$class->exception_class' method wants to use $exception_class\nfor exceptions, but it contains characters which are not word-characters or colons.";
+            }
+
+            # Alas, Perl does turn barewords into modules unless they're
+            # actually barewords.  As such, we're left doing a string eval
+            # to make sure we load our file correctly.
+
+            my $E;
+
+            {
+                local $@;   # We can't clobber $@, it's wrong!
+                eval "require $exception_class"; ## no critic
+                $E = $@;    # Save $E despite ending our local.
+            }
+
+            # We need quotes around $@ to make sure it's stringified
+            # while still in scope.  Without them, we run the risk of
+            # $@ having been cleared by us exiting the local() block.
+
+            confess "Failed to load '$exception_class'.\nThis may be a typo in the '$class->exception_class' method,\nor the '$exception_class' module may not exist.\n\n $E" if $E;
+
+            $class_loaded{$exception_class}++;
+
+        }
+
+        return $exception_class->new(@args);
     }
 }
 
+# For some reason, dying while replacing our subs doesn't
+# kill our calling program.  It simply stops the loading of
+# autodie and keeps going with everything else.  The _autocroak
+# sub allows us to die with a vegence.  It should *only* ever be
+# used for serious internal errors, since the results of it can't
+# be captured.
+
+sub _autocroak {
+    warn Carp::longmess(@_);
+    exit(255);  # Ugh!
+}
+
+package autodie::Scope::Guard;
+
+# This code schedules the cleanup of subroutines at the end of
+# scope.  It's directly inspired by chocolateboy's excellent
+# Scope::Guard module.
+
+sub new {
+    my ($class, $handler) = @_;
+
+    return bless $handler, $class;
+}
+
+sub DESTROY {
+    my ($self) = @_;
+
+    $self->();
+}
+
 1;
 
 __END__
 
 =head1 NAME
 
-Fatal - replace functions with equivalents which succeed or die
+Fatal - Replace functions with equivalents which succeed or die
 
 =head1 SYNOPSIS
 
     use Fatal qw(open close);
 
+    open(my $fh, "<", $filename);  # No need to check errors!
+
+    use File::Copy qw(move);
+    use Fatal qw(move);
+
+    move($file1, $file2); # No need to check errors!
+
     sub juggle { . . . }
-    import Fatal 'juggle';
+    Fatal->import('juggle');
+
+=head1 BEST PRACTICE
+
+B<Fatal has been obsoleted by the new L<autodie> pragma.> Please use
+L<autodie> in preference to C<Fatal>.  L<autodie> supports lexical scoping,
+throws real exception objects, and provides much nicer error messages.
+
+The use of C<:void> with Fatal is discouraged.
 
 =head1 DESCRIPTION
 
-C<Fatal> provides a way to conveniently replace functions which normally
-return a false value when they fail with equivalents which raise exceptions
-if they are not successful.  This lets you use these functions without
-having to test their return values explicitly on each call.  Exceptions
-can be caught using C<eval{}>.  See L<perlfunc> and L<perlvar> for details.
+C<Fatal> provides a way to conveniently replace
+functions which normally return a false value when they fail with
+equivalents which raise exceptions if they are not successful.  This
+lets you use these functions without having to test their return
+values explicitly on each call.  Exceptions can be caught using
+C<eval{}>.  See L<perlfunc> and L<perlvar> for details.
 
 The do-or-die equivalents are set up simply by calling Fatal's
 C<import> routine, passing it the names of the functions to be
 replaced.  You may wrap both user-defined functions and overridable
-CORE operators (except C<exec>, C<system> which cannot be expressed
-via prototypes) in this way.
+CORE operators (except C<exec>, C<system>, C<print>, or any other
+built-in that cannot be expressed via prototypes) in this way.
 
 If the symbol C<:void> appears in the import list, then functions
 named later in that import list raise an exception only when
 these are called in void context--that is, when their return
 values are ignored.  For example
 
-	use Fatal qw/:void open close/;
+    use Fatal qw/:void open close/;
 
-	# properly checked, so no exception raised on error
-	if(open(FH, "< /bogotic") {
-		warn "bogo file, dude: $!";
-	}
+    # properly checked, so no exception raised on error
+    if (not open(my $fh, '<' '/bogotic') {
+        warn "Can't open /bogotic: $!";
+    }
 
-	# not checked, so error raises an exception
-	close FH;
+    # not checked, so error raises an exception
+    close FH;
+
+The use of C<:void> is discouraged, as it can result in exceptions
+not being thrown if you I<accidentally> call a method without
+void context.  Use L<autodie> instead if you need to be able to
+disable autodying/Fatal behaviour for a small block of code.
+
+=head1 DIAGNOSTICS
+
+=over 4
+
+=item Bad subroutine name for Fatal: %s
+
+You've called C<Fatal> with an argument that doesn't look like
+a subroutine name, nor a switch that this version of Fatal
+understands.
+
+=item %s is not a Perl subroutine
+
+You've asked C<Fatal> to try and replace a subroutine which does not
+exist, or has not yet been defined.
+
+=item %s is neither a builtin, nor a Perl subroutine
+
+You've asked C<Fatal> to replace a subroutine, but it's not a Perl
+built-in, and C<Fatal> couldn't find it as a regular subroutine.
+It either doesn't exist or has not yet been defined.
+
+=item Cannot make the non-overridable %s fatal
+
+You've tried to use C<Fatal> on a Perl built-in that can't be
+overridden, such as C<print> or C<system>, which means that
+C<Fatal> can't help you, although some other modules might.
+See the L</"SEE ALSO"> section of this documentation.
+
+=item Internal error: %s
+
+You've found a bug in C<Fatal>.  Please report it using
+the C<perlbug> command.
+
+=back
 
 =head1 BUGS
 
-You should not fatalize functions that are called in list context, because this
-module tests whether a function has failed by testing the boolean truth of its
-return value in scalar context.
+C<Fatal> clobbers the context in which a function is called and always
+makes it a scalar context, except when the C<:void> tag is used.
+This problem does not exist in L<autodie>.
 
 =head1 AUTHOR
 
-Lionel Cons (CERN).
+Original module by Lionel Cons (CERN).
 
 Prototype updates by Ilya Zakharevich <ilya@math.ohio-state.edu>.
 
+L<autodie> support, bugfixes, extended diagnostics, C<system>
+support, and major overhauling by Paul Fenwick <pjf@perltraining.com.au>
+
+=head1 LICENSE
+
+This module is free software, you may distribute it under the
+same terms as Perl itself.
+
+=head1 SEE ALSO
+
+L<autodie> for a nicer way to use lexical Fatal.
+
+L<IPC::System::Simple> for a similar idea for calls to C<system()>
+and backticks.
+
 =cut