The Perl and Raku Conference 2025: Greenville, South Carolina - June 27-29 Learn more

GSAR / perl5.5.650 / lib / Fatal.pm 

            

              
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
—
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160

              
package Fatal;
use 5.005_64;
use Carp;
use strict;
our($AUTOLOAD, $Debug, $VERSION);
$VERSION = 1.02;
$Debug = 0 unless defined $Debug;
sub import {
    my $self = shift(@_);
    my($sym, $pkg);
    $pkg = (caller)[0];
    foreach $sym (@_) {
        &_make_fatal($sym, $pkg);
    }
};
sub AUTOLOAD {
    my $cmd = $AUTOLOAD;
    $cmd =~ s/.*:://;
    &_make_fatal($cmd, (caller)[0]);
    goto &$AUTOLOAD;
}
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,[$n+1,@out]);
  @out1;
}
sub write_invocation {
  my ($core, $call, $name, @argvs) = @_;
  if (@argvs == 1) {            # No optional arguments
    my @argv = @{$argvs[0]};
    shift @argv;
    return "\t" . one_invocation($core, $call, $name, @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, $name, @argv) . ";\n";
    }
    push @out, <<EOC;
        }
        die "$name(\@_): Do not expect to get ", scalar \@_, " arguments";
EOC
    return join '', @out;
  }
}
sub one_invocation {
  my ($core, $call, $name, @argv) = @_;
  local $" = ', ';
  return qq{$call(@argv) || croak "Can't $name(\@_)} . 
    ($core ? ': $!' : ', \$! is \"$!\"') . '"';
}
sub _make_fatal {
    my($sub, $pkg) = @_;
    my($name, $code, $sref, $real_proto, $proto, $core, $call);
    my $ini = $sub;
    $sub = "${pkg}::$sub" unless $sub =~ /::/;
    $name = $sub;
    $name =~ s/.*::// or $name =~ s/^&//;
    print "# _make_fatal: sub=$sub pkg=$pkg name=$name\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';
    } elsif ($sub eq $ini) {    # Stray user subroutine
        die "$sub is not a Perl subroutine" 
    } else {                    # CORE subroutine
        $proto = eval { prototype "CORE::$name" };
        die "$name is neither a builtin, nor a Perl subroutine" 
          if $@;
        die "Cannot make a non-overridable builtin fatal"
          if not defined $proto;
        $core = 1;
        $call = "CORE::$name";
    }
    if (defined $proto) {
      $real_proto = " ($proto)";
    } else {
      $real_proto = '';
      $proto = '@';
    }
    $code = <<EOS;
sub$real_proto {
        local(\$", \$!) = (', ', 0);
EOS
    my @protos = fill_protos($proto);
    $code .= write_invocation($core, $call, $name, @protos);
    $code .= "}\n";
    print $code if $Debug;
    {
      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} = $code;
    }
}
1;
__END__
=head1 NAME
Fatal - replace functions with equivalents which succeed or die
=head1 SYNOPSIS
    use Fatal qw(open close);
    sub juggle { . . . }
    import Fatal 'juggle';
=head1 DESCRIPTION
C<Fatal> provides a way to conveniently replace functions which normally
return a false value when they fail with equivalents which halt execution
if they are not successful.  This lets you use these functions without
having to test their return values explicitly on each call.   Errors are
reported via C<die>, so you can trap them using C<$SIG{__DIE__}> if you
wish to take some action before the program exits.
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.
=head1 AUTHOR
Lionel.Cons@cern.ch
prototype updates by Ilya Zakharevich ilya@math.ohio-state.edu
=cut