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e92e55da MB |
1 | package Fatal; |
2 | ||
3 | use Carp; | |
4 | use strict; | |
5 | use vars qw( $AUTOLOAD $Debug $VERSION); | |
6 | ||
7 | $VERSION = 1.02; | |
8 | ||
9 | $Debug = 0 unless defined $Debug; | |
10 | ||
11 | sub import { | |
12 | my $self = shift(@_); | |
13 | my($sym, $pkg); | |
14 | $pkg = (caller)[0]; | |
15 | foreach $sym (@_) { | |
16 | &_make_fatal($sym, $pkg); | |
17 | } | |
18 | }; | |
19 | ||
20 | sub AUTOLOAD { | |
21 | my $cmd = $AUTOLOAD; | |
22 | $cmd =~ s/.*:://; | |
23 | &_make_fatal($cmd, (caller)[0]); | |
24 | goto &$AUTOLOAD; | |
25 | } | |
26 | ||
27 | sub fill_protos { | |
28 | my $proto = shift; | |
29 | my ($n, $isref, @out, @out1, $seen_semi) = -1; | |
30 | while ($proto =~ /\S/) { | |
31 | $n++; | |
32 | push(@out1,[$n,@out]) if $seen_semi; | |
33 | push(@out, $1 . "{\$_[$n]}"), next if $proto =~ s/^\s*\\([\@%\$\&])//; | |
34 | push(@out, "\$_[$n]"), next if $proto =~ s/^\s*([*\$&])//; | |
35 | push(@out, "\@_[$n..\$#_]"), last if $proto =~ s/^\s*(;\s*)?\@//; | |
36 | $seen_semi = 1, $n--, next if $proto =~ s/^\s*;//; # XXXX ???? | |
37 | die "Unknown prototype letters: \"$proto\""; | |
38 | } | |
39 | push(@out1,[$n+1,@out]); | |
40 | @out1; | |
41 | } | |
42 | ||
43 | sub write_invocation { | |
44 | my ($core, $call, $name, @argvs) = @_; | |
45 | if (@argvs == 1) { # No optional arguments | |
46 | my @argv = @{$argvs[0]}; | |
47 | shift @argv; | |
48 | return "\t" . one_invocation($core, $call, $name, @argv) . ";\n"; | |
49 | } else { | |
50 | my $else = "\t"; | |
51 | my (@out, @argv, $n); | |
52 | while (@argvs) { | |
53 | @argv = @{shift @argvs}; | |
54 | $n = shift @argv; | |
55 | push @out, "$ {else}if (\@_ == $n) {\n"; | |
56 | $else = "\t} els"; | |
57 | push @out, | |
58 | "\t\treturn " . one_invocation($core, $call, $name, @argv) . ";\n"; | |
59 | } | |
60 | push @out, <<EOC; | |
61 | } | |
62 | die "$name(\@_): Do not expect to get ", scalar \@_, " arguments"; | |
63 | EOC | |
64 | return join '', @out; | |
65 | } | |
66 | } | |
67 | ||
68 | sub one_invocation { | |
69 | my ($core, $call, $name, @argv) = @_; | |
70 | local $" = ', '; | |
71 | return qq{$call(@argv) || croak "Can't $name(\@_)} . | |
72 | ($core ? ': $!' : ', \$! is \"$!\"') . '"'; | |
73 | } | |
74 | ||
75 | sub _make_fatal { | |
76 | my($sub, $pkg) = @_; | |
77 | my($name, $code, $sref, $real_proto, $proto, $core, $call); | |
78 | my $ini = $sub; | |
79 | ||
80 | $sub = "${pkg}::$sub" unless $sub =~ /::/; | |
81 | $name = $sub; | |
82 | $name =~ s/.*::// or $name =~ s/^&//; | |
83 | print "# _make_fatal: sub=$sub pkg=$pkg name=$name\n" if $Debug; | |
84 | croak "Bad subroutine name for Fatal: $name" unless $name =~ /^\w+$/; | |
85 | if (defined(&$sub)) { # user subroutine | |
86 | $sref = \&$sub; | |
87 | $proto = prototype $sref; | |
88 | $call = '&$sref'; | |
89 | } elsif ($sub eq $ini) { # Stray user subroutine | |
90 | die "$sub is not a Perl subroutine" | |
91 | } else { # CORE subroutine | |
92 | $proto = eval { prototype "CORE::$name" }; | |
93 | die "$name is neither a builtin, nor a Perl subroutine" | |
94 | if $@; | |
95 | die "Cannot make a non-overridable builtin fatal" | |
96 | if not defined $proto; | |
97 | $core = 1; | |
98 | $call = "CORE::$name"; | |
99 | } | |
100 | if (defined $proto) { | |
101 | $real_proto = " ($proto)"; | |
102 | } else { | |
103 | $real_proto = ''; | |
104 | $proto = '@'; | |
105 | } | |
106 | $code = <<EOS; | |
107 | sub$real_proto { | |
108 | local(\$", \$!) = (', ', 0); | |
109 | EOS | |
110 | my @protos = fill_protos($proto); | |
111 | $code .= write_invocation($core, $call, $name, @protos); | |
112 | $code .= "}\n"; | |
113 | print $code if $Debug; | |
2ba6ecf4 GS |
114 | { |
115 | no strict 'refs'; # to avoid: Can't use string (...) as a symbol ref ... | |
116 | $code = eval("package $pkg; use Carp; $code"); | |
117 | die if $@; | |
118 | local($^W) = 0; # to avoid: Subroutine foo redefined ... | |
119 | *{$sub} = $code; | |
120 | } | |
e92e55da MB |
121 | } |
122 | ||
123 | 1; | |
124 | ||
125 | __END__ | |
126 | ||
127 | =head1 NAME | |
128 | ||
129 | Fatal - replace functions with equivalents which succeed or die | |
130 | ||
131 | =head1 SYNOPSIS | |
132 | ||
133 | use Fatal qw(open close); | |
134 | ||
135 | sub juggle { . . . } | |
136 | import Fatal 'juggle'; | |
137 | ||
138 | =head1 DESCRIPTION | |
139 | ||
140 | C<Fatal> provides a way to conveniently replace functions which normally | |
141 | return a false value when they fail with equivalents which halt execution | |
142 | if they are not successful. This lets you use these functions without | |
143 | having to test their return values explicitly on each call. Errors are | |
144 | reported via C<die>, so you can trap them using C<$SIG{__DIE__}> if you | |
145 | wish to take some action before the program exits. | |
146 | ||
147 | The do-or-die equivalents are set up simply by calling Fatal's | |
148 | C<import> routine, passing it the names of the functions to be | |
149 | replaced. You may wrap both user-defined functions and overridable | |
150 | CORE operators (except C<exec>, C<system> which cannot be expressed | |
151 | via prototypes) in this way. | |
152 | ||
153 | =head1 AUTHOR | |
154 | ||
155 | Lionel.Cons@cern.ch | |
156 | ||
157 | prototype updates by Ilya Zakharevich ilya@math.ohio-state.edu | |
158 | ||
159 | =cut |