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
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
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);
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;
}
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, $void, @argvs) = @_;
if (@argvs == 1) { # No optional arguments
my @argv = @{$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;
}
}
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 ? ': $!' : ', \$! is \"$!\"') . '"';
}
}
sub _make_fatal {
my($sub, $pkg, $void) = @_;
my($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 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';
} 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, $void, @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 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.
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/;
# properly checked, so no exception raised on error
if(open(FH, "< /bogotic") {
warn "bogo file, dude: $!";
}
# not checked, so error raises an exception
close FH;
=head1 AUTHOR
Lionel.Cons@cern.ch
prototype updates by Ilya Zakharevich ilya@math.ohio-state.edu
=cut
|
