| 1 | package Fatal; |
| 2 | |
| 3 | use 5.006_001; |
| 4 | use Carp; |
| 5 | use strict; |
| 6 | our($AUTOLOAD, $Debug, $VERSION); |
| 7 | |
| 8 | $VERSION = 1.03; |
| 9 | |
| 10 | $Debug = 0 unless defined $Debug; |
| 11 | |
| 12 | sub import { |
| 13 | my $self = shift(@_); |
| 14 | my($sym, $pkg); |
| 15 | my $void = 0; |
| 16 | $pkg = (caller)[0]; |
| 17 | foreach $sym (@_) { |
| 18 | if ($sym eq ":void") { |
| 19 | $void = 1; |
| 20 | } |
| 21 | else { |
| 22 | &_make_fatal($sym, $pkg, $void); |
| 23 | } |
| 24 | } |
| 25 | }; |
| 26 | |
| 27 | sub AUTOLOAD { |
| 28 | my $cmd = $AUTOLOAD; |
| 29 | $cmd =~ s/.*:://; |
| 30 | &_make_fatal($cmd, (caller)[0]); |
| 31 | goto &$AUTOLOAD; |
| 32 | } |
| 33 | |
| 34 | sub fill_protos { |
| 35 | my $proto = shift; |
| 36 | my ($n, $isref, @out, @out1, $seen_semi) = -1; |
| 37 | while ($proto =~ /\S/) { |
| 38 | $n++; |
| 39 | push(@out1,[$n,@out]) if $seen_semi; |
| 40 | push(@out, $1 . "{\$_[$n]}"), next if $proto =~ s/^\s*\\([\@%\$\&])//; |
| 41 | push(@out, "\$_[$n]"), next if $proto =~ s/^\s*([*\$&])//; |
| 42 | push(@out, "\@_[$n..\$#_]"), last if $proto =~ s/^\s*(;\s*)?\@//; |
| 43 | $seen_semi = 1, $n--, next if $proto =~ s/^\s*;//; # XXXX ???? |
| 44 | die "Unknown prototype letters: \"$proto\""; |
| 45 | } |
| 46 | push(@out1,[$n+1,@out]); |
| 47 | @out1; |
| 48 | } |
| 49 | |
| 50 | sub write_invocation { |
| 51 | my ($core, $call, $name, $void, @argvs) = @_; |
| 52 | if (@argvs == 1) { # No optional arguments |
| 53 | my @argv = @{$argvs[0]}; |
| 54 | shift @argv; |
| 55 | return "\t" . one_invocation($core, $call, $name, $void, @argv) . ";\n"; |
| 56 | } else { |
| 57 | my $else = "\t"; |
| 58 | my (@out, @argv, $n); |
| 59 | while (@argvs) { |
| 60 | @argv = @{shift @argvs}; |
| 61 | $n = shift @argv; |
| 62 | push @out, "$ {else}if (\@_ == $n) {\n"; |
| 63 | $else = "\t} els"; |
| 64 | push @out, |
| 65 | "\t\treturn " . one_invocation($core, $call, $name, $void, @argv) . ";\n"; |
| 66 | } |
| 67 | push @out, <<EOC; |
| 68 | } |
| 69 | die "$name(\@_): Do not expect to get ", scalar \@_, " arguments"; |
| 70 | EOC |
| 71 | return join '', @out; |
| 72 | } |
| 73 | } |
| 74 | |
| 75 | sub one_invocation { |
| 76 | my ($core, $call, $name, $void, @argv) = @_; |
| 77 | local $" = ', '; |
| 78 | if ($void) { |
| 79 | return qq/(defined wantarray)?$call(@argv): |
| 80 | $call(@argv) || croak "Can't $name(\@_)/ . |
| 81 | ($core ? ': $!' : ', \$! is \"$!\"') . '"' |
| 82 | } else { |
| 83 | return qq{$call(@argv) || croak "Can't $name(\@_)} . |
| 84 | ($core ? ': $!' : ', \$! is \"$!\"') . '"'; |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | sub _make_fatal { |
| 89 | my($sub, $pkg, $void) = @_; |
| 90 | my($name, $code, $sref, $real_proto, $proto, $core, $call); |
| 91 | my $ini = $sub; |
| 92 | |
| 93 | $sub = "${pkg}::$sub" unless $sub =~ /::/; |
| 94 | $name = $sub; |
| 95 | $name =~ s/.*::// or $name =~ s/^&//; |
| 96 | print "# _make_fatal: sub=$sub pkg=$pkg name=$name void=$void\n" if $Debug; |
| 97 | croak "Bad subroutine name for Fatal: $name" unless $name =~ /^\w+$/; |
| 98 | if (defined(&$sub)) { # user subroutine |
| 99 | $sref = \&$sub; |
| 100 | $proto = prototype $sref; |
| 101 | $call = '&$sref'; |
| 102 | } elsif ($sub eq $ini) { # Stray user subroutine |
| 103 | die "$sub is not a Perl subroutine" |
| 104 | } else { # CORE subroutine |
| 105 | $proto = eval { prototype "CORE::$name" }; |
| 106 | die "$name is neither a builtin, nor a Perl subroutine" |
| 107 | if $@; |
| 108 | die "Cannot make a non-overridable builtin fatal" |
| 109 | if not defined $proto; |
| 110 | $core = 1; |
| 111 | $call = "CORE::$name"; |
| 112 | } |
| 113 | if (defined $proto) { |
| 114 | $real_proto = " ($proto)"; |
| 115 | } else { |
| 116 | $real_proto = ''; |
| 117 | $proto = '@'; |
| 118 | } |
| 119 | $code = <<EOS; |
| 120 | sub$real_proto { |
| 121 | local(\$", \$!) = (', ', 0); |
| 122 | EOS |
| 123 | my @protos = fill_protos($proto); |
| 124 | $code .= write_invocation($core, $call, $name, $void, @protos); |
| 125 | $code .= "}\n"; |
| 126 | print $code if $Debug; |
| 127 | { |
| 128 | no strict 'refs'; # to avoid: Can't use string (...) as a symbol ref ... |
| 129 | $code = eval("package $pkg; use Carp; $code"); |
| 130 | die if $@; |
| 131 | no warnings; # to avoid: Subroutine foo redefined ... |
| 132 | *{$sub} = $code; |
| 133 | } |
| 134 | } |
| 135 | |
| 136 | 1; |
| 137 | |
| 138 | __END__ |
| 139 | |
| 140 | =head1 NAME |
| 141 | |
| 142 | Fatal - replace functions with equivalents which succeed or die |
| 143 | |
| 144 | =head1 SYNOPSIS |
| 145 | |
| 146 | use Fatal qw(open close); |
| 147 | |
| 148 | sub juggle { . . . } |
| 149 | import Fatal 'juggle'; |
| 150 | |
| 151 | =head1 DESCRIPTION |
| 152 | |
| 153 | C<Fatal> provides a way to conveniently replace functions which normally |
| 154 | return a false value when they fail with equivalents which raise exceptions |
| 155 | if they are not successful. This lets you use these functions without |
| 156 | having to test their return values explicitly on each call. Exceptions |
| 157 | can be caught using C<eval{}>. See L<perlfunc> and L<perlvar> for details. |
| 158 | |
| 159 | The do-or-die equivalents are set up simply by calling Fatal's |
| 160 | C<import> routine, passing it the names of the functions to be |
| 161 | replaced. You may wrap both user-defined functions and overridable |
| 162 | CORE operators (except C<exec>, C<system> which cannot be expressed |
| 163 | via prototypes) in this way. |
| 164 | |
| 165 | If the symbol C<:void> appears in the import list, then functions |
| 166 | named later in that import list raise an exception only when |
| 167 | these are called in void context--that is, when their return |
| 168 | values are ignored. For example |
| 169 | |
| 170 | use Fatal qw/:void open close/; |
| 171 | |
| 172 | # properly checked, so no exception raised on error |
| 173 | if(open(FH, "< /bogotic") { |
| 174 | warn "bogo file, dude: $!"; |
| 175 | } |
| 176 | |
| 177 | # not checked, so error raises an exception |
| 178 | close FH; |
| 179 | |
| 180 | =head1 AUTHOR |
| 181 | |
| 182 | Lionel.Cons@cern.ch |
| 183 | |
| 184 | prototype updates by Ilya Zakharevich ilya@math.ohio-state.edu |
| 185 | |
| 186 | =cut |