/usr/share/perl/5.26.1/autouse.pm is in perl-modules-5.26 5.26.1-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 | package autouse;
#use strict; # debugging only
use 5.006; # use warnings
$autouse::VERSION = '1.11';
$autouse::DEBUG ||= 0;
sub vet_import ($);
sub croak {
require Carp;
Carp::croak(@_);
}
sub import {
my $class = @_ ? shift : 'autouse';
croak "usage: use $class MODULE [,SUBS...]" unless @_;
my $module = shift;
(my $pm = $module) =~ s{::}{/}g;
$pm .= '.pm';
if (exists $INC{$pm}) {
vet_import $module;
local $Exporter::ExportLevel = $Exporter::ExportLevel + 1;
# $Exporter::Verbose = 1;
return $module->import(map { (my $f = $_) =~ s/\(.*?\)$//; $f } @_);
}
# It is not loaded: need to do real work.
my $callpkg = caller(0);
print "autouse called from $callpkg\n" if $autouse::DEBUG;
my $index;
for my $f (@_) {
my $proto;
$proto = $1 if (my $func = $f) =~ s/\((.*)\)$//;
my $closure_import_func = $func; # Full name
my $closure_func = $func; # Name inside package
my $index = rindex($func, '::');
if ($index == -1) {
$closure_import_func = "${callpkg}::$func";
} else {
$closure_func = substr $func, $index + 2;
croak "autouse into different package attempted"
unless substr($func, 0, $index) eq $module;
}
my $load_sub = sub {
unless ($INC{$pm}) {
require $pm;
vet_import $module;
}
no warnings qw(redefine prototype);
*$closure_import_func = \&{"${module}::$closure_func"};
print "autousing $module; "
."imported $closure_func as $closure_import_func\n"
if $autouse::DEBUG;
goto &$closure_import_func;
};
if (defined $proto) {
*$closure_import_func = eval "sub ($proto) { goto &\$load_sub }"
|| die;
} else {
*$closure_import_func = $load_sub;
}
}
}
sub vet_import ($) {
my $module = shift;
if (my $import = $module->can('import')) {
croak "autoused module $module has unique import() method"
unless defined(&Exporter::import)
&& ($import == \&Exporter::import ||
$import == \&UNIVERSAL::import)
}
}
1;
__END__
=head1 NAME
autouse - postpone load of modules until a function is used
=head1 SYNOPSIS
use autouse 'Carp' => qw(carp croak);
carp "this carp was predeclared and autoused ";
=head1 DESCRIPTION
If the module C<Module> is already loaded, then the declaration
use autouse 'Module' => qw(func1 func2($;$));
is equivalent to
use Module qw(func1 func2);
if C<Module> defines func2() with prototype C<($;$)>, and func1() has
no prototypes. (At least if C<Module> uses C<Exporter>'s C<import>,
otherwise it is a fatal error.)
If the module C<Module> is not loaded yet, then the above declaration
declares functions func1() and func2() in the current package. When
these functions are called, they load the package C<Module> if needed,
and substitute themselves with the correct definitions.
=begin _deprecated
use Module qw(Module::func3);
will work and is the equivalent to:
use Module qw(func3);
It is not a very useful feature and has been deprecated.
=end _deprecated
=head1 WARNING
Using C<autouse> will move important steps of your program's execution
from compile time to runtime. This can
=over 4
=item *
Break the execution of your program if the module you C<autouse>d has
some initialization which it expects to be done early.
=item *
hide bugs in your code since important checks (like correctness of
prototypes) is moved from compile time to runtime. In particular, if
the prototype you specified on C<autouse> line is wrong, you will not
find it out until the corresponding function is executed. This will be
very unfortunate for functions which are not always called (note that
for such functions C<autouse>ing gives biggest win, for a workaround
see below).
=back
To alleviate the second problem (partially) it is advised to write
your scripts like this:
use Module;
use autouse Module => qw(carp($) croak(&$));
carp "this carp was predeclared and autoused ";
The first line ensures that the errors in your argument specification
are found early. When you ship your application you should comment
out the first line, since it makes the second one useless.
=head1 AUTHOR
Ilya Zakharevich (ilya@math.ohio-state.edu)
=head1 SEE ALSO
perl(1).
=cut
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