perl/lib/SelfLoader.pm

package SelfLoader;
# use Carp;
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(AUTOLOAD);
$VERSION = "1.0904";
sub Version {$VERSION}
$DEBUG = 0;

my %Cache;      # private cache for all SelfLoader's client packages

# allow checking for valid ': attrlist' attachments
# (we use 'our' rather than 'my' here, due to the rather complex and buggy
# behaviour of lexicals with qr// and (??{$lex}) )
our $nested;
$nested = qr{ \( (?: (?> [^()]+ ) | (??{ $nested }) )* \) }x;
our $one_attr = qr{ (?> (?! \d) \w+ (?:$nested)? ) (?:\s*\:\s*|\s+(?!\:)) }x;
our $attr_list = qr{ \s* : \s* (?: $one_attr )* }x;

sub croak { require Carp; goto &Carp::croak }

AUTOLOAD {
    print STDERR "SelfLoader::AUTOLOAD for $AUTOLOAD\n" if $DEBUG;
    my $SL_code = $Cache{$AUTOLOAD};
    my $save = $@; # evals in both AUTOLOAD and _load_stubs can corrupt $@
    unless ($SL_code) {
        # Maybe this pack had stubs before __DATA__, and never initialized.
        # Or, this maybe an automatic DESTROY method call when none exists.
        $AUTOLOAD =~ m/^(.*)::/;
        SelfLoader->_load_stubs($1) unless exists $Cache{"${1}::<DATA"};
        $SL_code = $Cache{$AUTOLOAD};
        $SL_code = "sub $AUTOLOAD { }"
            if (!$SL_code and $AUTOLOAD =~ m/::DESTROY$/);
        croak "Undefined subroutine $AUTOLOAD" unless $SL_code;
    }
    print STDERR "SelfLoader::AUTOLOAD eval: $SL_code\n" if $DEBUG;

    eval $SL_code;
    if ($@) {
        $@ =~ s/ at .*\n//;
        croak $@;
    }
    $@ = $save;
    defined(&$AUTOLOAD) || die "SelfLoader inconsistency error";
    delete $Cache{$AUTOLOAD};
    goto &$AUTOLOAD
}

sub load_stubs { shift->_load_stubs((caller)[0]) }

sub _load_stubs {
    # $endlines is used by Devel::SelfStubber to capture lines after __END__
    my($self, $callpack, $endlines) = @_;
    my $fh = \*{"${callpack}::DATA"};
    my $currpack = $callpack;
    my($line,$name,@lines, @stubs, $protoype);

    print STDERR "SelfLoader::load_stubs($callpack)\n" if $DEBUG;
    croak("$callpack doesn't contain an __DATA__ token")
        unless fileno($fh);
    $Cache{"${currpack}::<DATA"} = 1;   # indicate package is cached

    local($/) = "\n";
    while(defined($line = <$fh>) and $line !~ m/^__END__/) {
        if ($line =~ m/^sub\s+([\w:]+)\s*((?:\([\\\$\@\%\&\*\;]*\))?(?:$attr_list)?)/) {
            push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
            $protoype = $2;
            @lines = ($line);
            if (index($1,'::') == -1) {         # simple sub name
                $name = "${currpack}::$1";
            } else {                            # sub name with package
                $name = $1;
                $name =~ m/^(.*)::/;
                if (defined(&{"${1}::AUTOLOAD"})) {
                    \&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD ||
                        die 'SelfLoader Error: attempt to specify Selfloading',
                            " sub $name in non-selfloading module $1";
                } else {
                    $self->export($1,'AUTOLOAD');
                }
            }
        } elsif ($line =~ m/^package\s+([\w:]+)/) { # A package declared
            push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
            $self->_package_defined($line);
            $name = '';
            @lines = ();
            $currpack = $1;
            $Cache{"${currpack}::<DATA"} = 1;   # indicate package is cached
            if (defined(&{"${1}::AUTOLOAD"})) {
                \&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD ||
                    die 'SelfLoader Error: attempt to specify Selfloading',
                        " package $currpack which already has AUTOLOAD";
            } else {
                $self->export($currpack,'AUTOLOAD');
            }
        } else {
            push(@lines,$line);
        }
    }
    if (defined($line) && $line =~ /^__END__/) { # __END__
        unless ($line =~ /^__END__\s*DATA/) {
            if ($endlines) {
                # Devel::SelfStubber would like us to capture the lines after
                # __END__ so it can write out the entire file
                @$endlines = <$fh>;
            }
            close($fh);
        }
    }
    push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
    eval join('', @stubs) if @stubs;
}


sub _add_to_cache {
    my($self,$fullname,$pack,$lines, $protoype) = @_;
    return () unless $fullname;
    (require Carp), Carp::carp("Redefining sub $fullname")
      if exists $Cache{$fullname};
    $Cache{$fullname} = join('', "package $pack; ",@$lines);
    print STDERR "SelfLoader cached $fullname: $Cache{$fullname}" if $DEBUG;
    # return stub to be eval'd
    defined($protoype) ? "sub $fullname $protoype;" : "sub $fullname;"
}

sub _package_defined {}

1;
__END__

=head1 NAME

SelfLoader - load functions only on demand

=head1 SYNOPSIS

    package FOOBAR;
    use SelfLoader;

    ... (initializing code)

    __DATA__
    sub {....


=head1 DESCRIPTION

This module tells its users that functions in the FOOBAR package are to be
autoloaded from after the C<__DATA__> token.  See also
L<perlsub/"Autoloading">.

=head2 The __DATA__ token

The C<__DATA__> token tells the perl compiler that the perl code
for compilation is finished. Everything after the C<__DATA__> token
is available for reading via the filehandle FOOBAR::DATA,
where FOOBAR is the name of the current package when the C<__DATA__>
token is reached. This works just the same as C<__END__> does in
package 'main', but for other modules data after C<__END__> is not
automatically retrievable, whereas data after C<__DATA__> is.
The C<__DATA__> token is not recognized in versions of perl prior to
5.001m.

Note that it is possible to have C<__DATA__> tokens in the same package
in multiple files, and that the last C<__DATA__> token in a given
package that is encountered by the compiler is the one accessible
by the filehandle. This also applies to C<__END__> and main, i.e. if
the 'main' program has an C<__END__>, but a module 'require'd (_not_ 'use'd)
by that program has a 'package main;' declaration followed by an 'C<__DATA__>',
then the C<DATA> filehandle is set to access the data after the C<__DATA__>
in the module, _not_ the data after the C<__END__> token in the 'main'
program, since the compiler encounters the 'require'd file later.

=head2 SelfLoader autoloading

The B<SelfLoader> works by the user placing the C<__DATA__>
token I<after> perl code which needs to be compiled and
run at 'require' time, but I<before> subroutine declarations
that can be loaded in later - usually because they may never
be called.

The B<SelfLoader> will read from the FOOBAR::DATA filehandle to
load in the data after C<__DATA__>, and load in any subroutine
when it is called. The costs are the one-time parsing of the
data after C<__DATA__>, and a load delay for the _first_
call of any autoloaded function. The benefits (hopefully)
are a speeded up compilation phase, with no need to load
functions which are never used.

The B<SelfLoader> will stop reading from C<__DATA__> if
it encounters the C<__END__> token - just as you would expect.
If the C<__END__> token is present, and is followed by the
token DATA, then the B<SelfLoader> leaves the FOOBAR::DATA
filehandle open on the line after that token.

The B<SelfLoader> exports the C<AUTOLOAD> subroutine to the
package using the B<SelfLoader>, and this loads the called
subroutine when it is first called.

There is no advantage to putting subroutines which will _always_
be called after the C<__DATA__> token.

=head2 Autoloading and package lexicals

A 'my $pack_lexical' statement makes the variable $pack_lexical
local _only_ to the file up to the C<__DATA__> token. Subroutines
declared elsewhere _cannot_ see these types of variables,
just as if you declared subroutines in the package but in another
file, they cannot see these variables.

So specifically, autoloaded functions cannot see package
lexicals (this applies to both the B<SelfLoader> and the Autoloader).
The C<vars> pragma provides an alternative to defining package-level
globals that will be visible to autoloaded routines. See the documentation
on B<vars> in the pragma section of L<perlmod>.

=head2 SelfLoader and AutoLoader

The B<SelfLoader> can replace the AutoLoader - just change 'use AutoLoader'
to 'use SelfLoader' (though note that the B<SelfLoader> exports
the AUTOLOAD function - but if you have your own AUTOLOAD and
are using the AutoLoader too, you probably know what you're doing),
and the C<__END__> token to C<__DATA__>. You will need perl version 5.001m
or later to use this (version 5.001 with all patches up to patch m).

There is no need to inherit from the B<SelfLoader>.

The B<SelfLoader> works similarly to the AutoLoader, but picks up the
subs from after the C<__DATA__> instead of in the 'lib/auto' directory.
There is a maintenance gain in not needing to run AutoSplit on the module
at installation, and a runtime gain in not needing to keep opening and
closing files to load subs. There is a runtime loss in needing
to parse the code after the C<__DATA__>. Details of the B<AutoLoader> and
another view of these distinctions can be found in that module's
documentation.

=head2 __DATA__, __END__, and the FOOBAR::DATA filehandle.

This section is only relevant if you want to use
the C<FOOBAR::DATA> together with the B<SelfLoader>.

Data after the C<__DATA__> token in a module is read using the
FOOBAR::DATA filehandle. C<__END__> can still be used to denote the end
of the C<__DATA__> section if followed by the token DATA - this is supported
by the B<SelfLoader>. The C<FOOBAR::DATA> filehandle is left open if an
C<__END__> followed by a DATA is found, with the filehandle positioned at
the start of the line after the C<__END__> token. If no C<__END__> token is
present, or an C<__END__> token with no DATA token on the same line, then
the filehandle is closed.

The B<SelfLoader> reads from wherever the current
position of the C<FOOBAR::DATA> filehandle is, until the
EOF or C<__END__>. This means that if you want to use
that filehandle (and ONLY if you want to), you should either

1. Put all your subroutine declarations immediately after
the C<__DATA__> token and put your own data after those
declarations, using the C<__END__> token to mark the end
of subroutine declarations. You must also ensure that the B<SelfLoader>
reads first by  calling 'SelfLoader-E<gt>load_stubs();', or by using a
function which is selfloaded;

or

2. You should read the C<FOOBAR::DATA> filehandle first, leaving
the handle open and positioned at the first line of subroutine
declarations.

You could conceivably do both.

=head2 Classes and inherited methods.

For modules which are not classes, this section is not relevant.
This section is only relevant if you have methods which could
be inherited.

A subroutine stub (or forward declaration) looks like

  sub stub;

i.e. it is a subroutine declaration without the body of the
subroutine. For modules which are not classes, there is no real
need for stubs as far as autoloading is concerned.

For modules which ARE classes, and need to handle inherited methods,
stubs are needed to ensure that the method inheritance mechanism works
properly. You can load the stubs into the module at 'require' time, by
adding the statement 'SelfLoader-E<gt>load_stubs();' to the module to do
this.

The alternative is to put the stubs in before the C<__DATA__> token BEFORE
releasing the module, and for this purpose the C<Devel::SelfStubber>
module is available.  However this does require the extra step of ensuring
that the stubs are in the module. If this is done I strongly recommend
that this is done BEFORE releasing the module - it should NOT be done
at install time in general.

=head1 Multiple packages and fully qualified subroutine names

Subroutines in multiple packages within the same file are supported - but you
should note that this requires exporting the C<SelfLoader::AUTOLOAD> to
every package which requires it. This is done automatically by the
B<SelfLoader> when it first loads the subs into the cache, but you should
really specify it in the initialization before the C<__DATA__> by putting
a 'use SelfLoader' statement in each package.

Fully qualified subroutine names are also supported. For example,

   __DATA__
   sub foo::bar {23}
   package baz;
   sub dob {32}

will all be loaded correctly by the B<SelfLoader>, and the B<SelfLoader>
will ensure that the packages 'foo' and 'baz' correctly have the
B<SelfLoader> C<AUTOLOAD> method when the data after C<__DATA__> is first
parsed.

=cut
Revision:	1.1
Committed:	Thu Jun 30 14:27:08 2005 UTC (21 years, 3 months ago) by root
Branch:	MAIN
CVS Tags:	PERL-5-8-7, HEAD
Branch point for:	PERL
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	package SelfLoader;
2			# use Carp;
3			require Exporter;
4			@ISA = qw(Exporter);
5			@EXPORT = qw(AUTOLOAD);
6			$VERSION = "1.0904";
7			sub Version {$VERSION}
8			$DEBUG = 0;
9
10			my %Cache; # private cache for all SelfLoader's client packages
11
12			# allow checking for valid ': attrlist' attachments
13			# (we use 'our' rather than 'my' here, due to the rather complex and buggy
14			# behaviour of lexicals with qr// and (??{$lex}) )
15			our $nested;
16			$nested = qr{ \( (?: (?> [^()]+ ) \| (??{ $nested }) )* \) }x;
17			our $one_attr = qr{ (?> (?! \d) \w+ (?:$nested)? ) (?:\s\:\s\|\s+(?!\:)) }x;
18			our $attr_list = qr{ \s* : \s* (?: $one_attr )* }x;
19
20			sub croak { require Carp; goto &Carp::croak }
21
22			AUTOLOAD {
23			print STDERR "SelfLoader::AUTOLOAD for $AUTOLOAD\n" if $DEBUG;
24			my $SL_code = $Cache{$AUTOLOAD};
25			my $save = $@; # evals in both AUTOLOAD and _load_stubs can corrupt $@
26			unless ($SL_code) {
27			# Maybe this pack had stubs before __DATA__, and never initialized.
28			# Or, this maybe an automatic DESTROY method call when none exists.
29			$AUTOLOAD =~ m/^(.*)::/;
30			SelfLoader->_load_stubs($1) unless exists $Cache{"${1}::<DATA"};
31			$SL_code = $Cache{$AUTOLOAD};
32			$SL_code = "sub $AUTOLOAD { }"
33			if (!$SL_code and $AUTOLOAD =~ m/::DESTROY$/);
34			croak "Undefined subroutine $AUTOLOAD" unless $SL_code;
35			}
36			print STDERR "SelfLoader::AUTOLOAD eval: $SL_code\n" if $DEBUG;
37
38			eval $SL_code;
39			if ($@) {
40			$@ =~ s/ at .*\n//;
41			croak $@;
42			}
43			$@ = $save;
44			defined(&$AUTOLOAD) \|\| die "SelfLoader inconsistency error";
45			delete $Cache{$AUTOLOAD};
46			goto &$AUTOLOAD
47			}
48
49			sub load_stubs { shift->_load_stubs((caller)[0]) }
50
51			sub _load_stubs {
52			# $endlines is used by Devel::SelfStubber to capture lines after __END__
53			my($self, $callpack, $endlines) = @_;
54			my $fh = \*{"${callpack}::DATA"};
55			my $currpack = $callpack;
56			my($line,$name,@lines, @stubs, $protoype);
57
58			print STDERR "SelfLoader::load_stubs($callpack)\n" if $DEBUG;
59			croak("$callpack doesn't contain an __DATA__ token")
60			unless fileno($fh);
61			$Cache{"${currpack}::<DATA"} = 1; # indicate package is cached
62
63			local($/) = "\n";
64			while(defined($line = <$fh>) and $line !~ m/^__END__/) {
65			if ($line =~ m/^sub\s+([\w:]+)\s((?:\([\\\$\@\%\&\\;]*\))?(?:$attr_list)?)/) {
66			push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
67			$protoype = $2;
68			@lines = ($line);
69			if (index($1,'::') == -1) { # simple sub name
70			$name = "${currpack}::$1";
71			} else { # sub name with package
72			$name = $1;
73			$name =~ m/^(.*)::/;
74			if (defined(&{"${1}::AUTOLOAD"})) {
75			\&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD \|\|
76			die 'SelfLoader Error: attempt to specify Selfloading',
77			" sub $name in non-selfloading module $1";
78			} else {
79			$self->export($1,'AUTOLOAD');
80			}
81			}
82			} elsif ($line =~ m/^package\s+([\w:]+)/) { # A package declared
83			push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
84			$self->_package_defined($line);
85			$name = '';
86			@lines = ();
87			$currpack = $1;
88			$Cache{"${currpack}::<DATA"} = 1; # indicate package is cached
89			if (defined(&{"${1}::AUTOLOAD"})) {
90			\&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD \|\|
91			die 'SelfLoader Error: attempt to specify Selfloading',
92			" package $currpack which already has AUTOLOAD";
93			} else {
94			$self->export($currpack,'AUTOLOAD');
95			}
96			} else {
97			push(@lines,$line);
98			}
99			}
100			if (defined($line) && $line =~ /^__END__/) { # __END__
101			unless ($line =~ /^__END__\s*DATA/) {
102			if ($endlines) {
103			# Devel::SelfStubber would like us to capture the lines after
104			# __END__ so it can write out the entire file
105			@$endlines = <$fh>;
106			}
107			close($fh);
108			}
109			}
110			push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
111			eval join('', @stubs) if @stubs;
112			}
113
114
115			sub _add_to_cache {
116			my($self,$fullname,$pack,$lines, $protoype) = @_;
117			return () unless $fullname;
118			(require Carp), Carp::carp("Redefining sub $fullname")
119			if exists $Cache{$fullname};
120			$Cache{$fullname} = join('', "package $pack; ",@$lines);
121			print STDERR "SelfLoader cached $fullname: $Cache{$fullname}" if $DEBUG;
122			# return stub to be eval'd
123			defined($protoype) ? "sub $fullname $protoype;" : "sub $fullname;"
124			}
125
126			sub _package_defined {}
127
128			1;
129			__END__
130
131			=head1 NAME
132
133			SelfLoader - load functions only on demand
134
135			=head1 SYNOPSIS
136
137			package FOOBAR;
138			use SelfLoader;
139
140			... (initializing code)
141
142			__DATA__
143			sub {....
144
145
146			=head1 DESCRIPTION
147
148			This module tells its users that functions in the FOOBAR package are to be
149			autoloaded from after the C<__DATA__> token. See also
150			L<perlsub/"Autoloading">.
151
152			=head2 The __DATA__ token
153
154			The C<__DATA__> token tells the perl compiler that the perl code
155			for compilation is finished. Everything after the C<__DATA__> token
156			is available for reading via the filehandle FOOBAR::DATA,
157			where FOOBAR is the name of the current package when the C<__DATA__>
158			token is reached. This works just the same as C<__END__> does in
159			package 'main', but for other modules data after C<__END__> is not
160			automatically retrievable, whereas data after C<__DATA__> is.
161			The C<__DATA__> token is not recognized in versions of perl prior to
162			5.001m.
163
164			Note that it is possible to have C<__DATA__> tokens in the same package
165			in multiple files, and that the last C<__DATA__> token in a given
166			package that is encountered by the compiler is the one accessible
167			by the filehandle. This also applies to C<__END__> and main, i.e. if
168			the 'main' program has an C<__END__>, but a module 'require'd (_not_ 'use'd)
169			by that program has a 'package main;' declaration followed by an 'C<__DATA__>',
170			then the C<DATA> filehandle is set to access the data after the C<__DATA__>
171			in the module, _not_ the data after the C<__END__> token in the 'main'
172			program, since the compiler encounters the 'require'd file later.
173
174			=head2 SelfLoader autoloading
175
176			The B<SelfLoader> works by the user placing the C<__DATA__>
177			token I<after> perl code which needs to be compiled and
178			run at 'require' time, but I<before> subroutine declarations
179			that can be loaded in later - usually because they may never
180			be called.
181
182			The B<SelfLoader> will read from the FOOBAR::DATA filehandle to
183			load in the data after C<__DATA__>, and load in any subroutine
184			when it is called. The costs are the one-time parsing of the
185			data after C<__DATA__>, and a load delay for the _first_
186			call of any autoloaded function. The benefits (hopefully)
187			are a speeded up compilation phase, with no need to load
188			functions which are never used.
189
190			The B<SelfLoader> will stop reading from C<__DATA__> if
191			it encounters the C<__END__> token - just as you would expect.
192			If the C<__END__> token is present, and is followed by the
193			token DATA, then the B<SelfLoader> leaves the FOOBAR::DATA
194			filehandle open on the line after that token.
195
196			The B<SelfLoader> exports the C<AUTOLOAD> subroutine to the
197			package using the B<SelfLoader>, and this loads the called
198			subroutine when it is first called.
199
200			There is no advantage to putting subroutines which will _always_
201			be called after the C<__DATA__> token.
202
203			=head2 Autoloading and package lexicals
204
205			A 'my $pack_lexical' statement makes the variable $pack_lexical
206			local _only_ to the file up to the C<__DATA__> token. Subroutines
207			declared elsewhere _cannot_ see these types of variables,
208			just as if you declared subroutines in the package but in another
209			file, they cannot see these variables.
210
211			So specifically, autoloaded functions cannot see package
212			lexicals (this applies to both the B<SelfLoader> and the Autoloader).
213			The C<vars> pragma provides an alternative to defining package-level
214			globals that will be visible to autoloaded routines. See the documentation
215			on B<vars> in the pragma section of L<perlmod>.
216
217			=head2 SelfLoader and AutoLoader
218
219			The B<SelfLoader> can replace the AutoLoader - just change 'use AutoLoader'
220			to 'use SelfLoader' (though note that the B<SelfLoader> exports
221			the AUTOLOAD function - but if you have your own AUTOLOAD and
222			are using the AutoLoader too, you probably know what you're doing),
223			and the C<__END__> token to C<__DATA__>. You will need perl version 5.001m
224			or later to use this (version 5.001 with all patches up to patch m).
225
226			There is no need to inherit from the B<SelfLoader>.
227
228			The B<SelfLoader> works similarly to the AutoLoader, but picks up the
229			subs from after the C<__DATA__> instead of in the 'lib/auto' directory.
230			There is a maintenance gain in not needing to run AutoSplit on the module
231			at installation, and a runtime gain in not needing to keep opening and
232			closing files to load subs. There is a runtime loss in needing
233			to parse the code after the C<__DATA__>. Details of the B<AutoLoader> and
234			another view of these distinctions can be found in that module's
235			documentation.
236
237			=head2 __DATA__, __END__, and the FOOBAR::DATA filehandle.
238
239			This section is only relevant if you want to use
240			the C<FOOBAR::DATA> together with the B<SelfLoader>.
241
242			Data after the C<__DATA__> token in a module is read using the
243			FOOBAR::DATA filehandle. C<__END__> can still be used to denote the end
244			of the C<__DATA__> section if followed by the token DATA - this is supported
245			by the B<SelfLoader>. The C<FOOBAR::DATA> filehandle is left open if an
246			C<__END__> followed by a DATA is found, with the filehandle positioned at
247			the start of the line after the C<__END__> token. If no C<__END__> token is
248			present, or an C<__END__> token with no DATA token on the same line, then
249			the filehandle is closed.
250
251			The B<SelfLoader> reads from wherever the current
252			position of the C<FOOBAR::DATA> filehandle is, until the
253			EOF or C<__END__>. This means that if you want to use
254			that filehandle (and ONLY if you want to), you should either
255
256			1. Put all your subroutine declarations immediately after
257			the C<__DATA__> token and put your own data after those
258			declarations, using the C<__END__> token to mark the end
259			of subroutine declarations. You must also ensure that the B<SelfLoader>
260			reads first by calling 'SelfLoader-E<gt>load_stubs();', or by using a
261			function which is selfloaded;
262
263			or
264
265			2. You should read the C<FOOBAR::DATA> filehandle first, leaving
266			the handle open and positioned at the first line of subroutine
267			declarations.
268
269			You could conceivably do both.
270
271			=head2 Classes and inherited methods.
272
273			For modules which are not classes, this section is not relevant.
274			This section is only relevant if you have methods which could
275			be inherited.
276
277			A subroutine stub (or forward declaration) looks like
278
279			sub stub;
280
281			i.e. it is a subroutine declaration without the body of the
282			subroutine. For modules which are not classes, there is no real
283			need for stubs as far as autoloading is concerned.
284
285			For modules which ARE classes, and need to handle inherited methods,
286			stubs are needed to ensure that the method inheritance mechanism works
287			properly. You can load the stubs into the module at 'require' time, by
288			adding the statement 'SelfLoader-E<gt>load_stubs();' to the module to do
289			this.
290
291			The alternative is to put the stubs in before the C<__DATA__> token BEFORE
292			releasing the module, and for this purpose the C<Devel::SelfStubber>
293			module is available. However this does require the extra step of ensuring
294			that the stubs are in the module. If this is done I strongly recommend
295			that this is done BEFORE releasing the module - it should NOT be done
296			at install time in general.
297
298			=head1 Multiple packages and fully qualified subroutine names
299
300			Subroutines in multiple packages within the same file are supported - but you
301			should note that this requires exporting the C<SelfLoader::AUTOLOAD> to
302			every package which requires it. This is done automatically by the
303			B<SelfLoader> when it first loads the subs into the cache, but you should
304			really specify it in the initialization before the C<__DATA__> by putting
305			a 'use SelfLoader' statement in each package.
306
307			Fully qualified subroutine names are also supported. For example,
308
309			__DATA__
310			sub foo::bar {23}
311			package baz;
312			sub dob {32}
313
314			will all be loaded correctly by the B<SelfLoader>, and the B<SelfLoader>
315			will ensure that the packages 'foo' and 'baz' correctly have the
316			B<SelfLoader> C<AUTOLOAD> method when the data after C<__DATA__> is first
317			parsed.
318
319			=cut