4 our $VERSION = "1.13_03";
6 # The following bit of eval-magic is necessary to make this work on
8 use vars qw/$AttrList/;
12 use 5.009005; # due to new regexp features
13 # allow checking for valid ': attrlist' attachments
21 (?<nested> \( (?: [^()]++ | (?&nested)++ )*+ \) ) ?
23 (?: \s* : \s* | \s+ (?! :) )
31 # allow checking for valid ': attrlist' attachments
32 # (we use 'our' rather than 'my' here, due to the rather complex and buggy
33 # behaviour of lexicals with qr// and (??{$lex}) )
35 $nested = qr{ \( (?: (?> [^()]+ ) | (??{ $nested }) )* \) }x;
36 our $one_attr = qr{ (?> (?! \d) \w+ (?:$nested)? ) (?:\s*\:\s*|\s+(?!\:)) }x;
37 $AttrList = qr{ \s* : \s* (?: $one_attr )* }x;
42 our @ISA = qw(Exporter);
43 our @EXPORT = qw(AUTOLOAD);
44 sub Version {$VERSION}
47 my %Cache; # private cache for all SelfLoader's client packages
49 # in croak and carp, protect $@ from "require Carp;" RT #40216
51 sub croak { { local $@; require Carp; } goto &Carp::croak }
52 sub carp { { local $@; require Carp; } goto &Carp::carp }
56 print STDERR "SelfLoader::AUTOLOAD for $AUTOLOAD\n" if DEBUG;
57 my $SL_code = $Cache{$AUTOLOAD};
58 my $save = $@; # evals in both AUTOLOAD and _load_stubs can corrupt $@
60 # Maybe this pack had stubs before __DATA__, and never initialized.
61 # Or, this maybe an automatic DESTROY method call when none exists.
62 $AUTOLOAD =~ m/^(.*)::/;
63 SelfLoader->_load_stubs($1) unless exists $Cache{"${1}::<DATA"};
64 $SL_code = $Cache{$AUTOLOAD};
65 $SL_code = "sub $AUTOLOAD { }"
66 if (!$SL_code and $AUTOLOAD =~ m/::DESTROY$/);
67 croak "Undefined subroutine $AUTOLOAD" unless $SL_code;
69 print STDERR "SelfLoader::AUTOLOAD eval: $SL_code\n" if DEBUG;
80 defined(&$AUTOLOAD) || die "SelfLoader inconsistency error";
81 delete $Cache{$AUTOLOAD};
85 sub load_stubs { shift->_load_stubs((caller)[0]) }
88 # $endlines is used by Devel::SelfStubber to capture lines after __END__
89 my($self, $callpack, $endlines) = @_;
91 my $fh = \*{"${callpack}::DATA"};
93 my $currpack = $callpack;
94 my($line,$name,@lines, @stubs, $protoype);
96 print STDERR "SelfLoader::load_stubs($callpack)\n" if DEBUG;
97 croak("$callpack doesn't contain an __DATA__ token")
98 unless defined fileno($fh);
99 # Protect: fork() shares the file pointer between the parent and the kid
100 if(sysseek($fh, tell($fh), 0)) {
101 open my $nfh, '<&', $fh or croak "reopen: $!";# dup() the fd
102 close $fh or die "close: $1"; # autocloses, but be paranoid
103 open $fh, '<&', $nfh or croak "reopen2: $!"; # dup() the fd "back"
104 close $nfh or die "close after reopen: $1"; # autocloses, but be paranoid
106 $Cache{"${currpack}::<DATA"} = 1; # indicate package is cached
109 while(defined($line = <$fh>) and $line !~ m/^__END__/) {
110 if ($line =~ m/^\s*sub\s+([\w:]+)\s*((?:\([\\\$\@\%\&\*\;]*\))?(?:$AttrList)?)/) {
111 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
114 if (index($1,'::') == -1) { # simple sub name
115 $name = "${currpack}::$1";
116 } else { # sub name with package
119 if (defined(&{"${1}::AUTOLOAD"})) {
120 \&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD ||
121 die 'SelfLoader Error: attempt to specify Selfloading',
122 " sub $name in non-selfloading module $1";
124 $self->export($1,'AUTOLOAD');
127 } elsif ($line =~ m/^package\s+([\w:]+)/) { # A package declared
128 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
129 $self->_package_defined($line);
133 $Cache{"${currpack}::<DATA"} = 1; # indicate package is cached
134 if (defined(&{"${1}::AUTOLOAD"})) {
135 \&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD ||
136 die 'SelfLoader Error: attempt to specify Selfloading',
137 " package $currpack which already has AUTOLOAD";
139 $self->export($currpack,'AUTOLOAD');
145 if (defined($line) && $line =~ /^__END__/) { # __END__
146 unless ($line =~ /^__END__\s*DATA/) {
148 # Devel::SelfStubber would like us to capture the lines after
149 # __END__ so it can write out the entire file
155 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
157 eval join('', @stubs) if @stubs;
162 my($self,$fullname,$pack,$lines, $protoype) = @_;
163 return () unless $fullname;
164 carp("Redefining sub $fullname")
165 if exists $Cache{$fullname};
166 $Cache{$fullname} = join('', "package $pack; ",@$lines);
167 print STDERR "SelfLoader cached $fullname: $Cache{$fullname}" if DEBUG;
168 # return stub to be eval'd
169 defined($protoype) ? "sub $fullname $protoype;" : "sub $fullname;"
172 sub _package_defined {}
179 SelfLoader - load functions only on demand
186 ... (initializing code)
194 This module tells its users that functions in the FOOBAR package are to be
195 autoloaded from after the C<__DATA__> token. See also
196 L<perlsub/"Autoloading">.
198 =head2 The __DATA__ token
200 The C<__DATA__> token tells the perl compiler that the perl code
201 for compilation is finished. Everything after the C<__DATA__> token
202 is available for reading via the filehandle FOOBAR::DATA,
203 where FOOBAR is the name of the current package when the C<__DATA__>
204 token is reached. This works just the same as C<__END__> does in
205 package 'main', but for other modules data after C<__END__> is not
206 automatically retrievable, whereas data after C<__DATA__> is.
207 The C<__DATA__> token is not recognized in versions of perl prior to
210 Note that it is possible to have C<__DATA__> tokens in the same package
211 in multiple files, and that the last C<__DATA__> token in a given
212 package that is encountered by the compiler is the one accessible
213 by the filehandle. This also applies to C<__END__> and main, i.e. if
214 the 'main' program has an C<__END__>, but a module 'require'd (_not_ 'use'd)
215 by that program has a 'package main;' declaration followed by an 'C<__DATA__>',
216 then the C<DATA> filehandle is set to access the data after the C<__DATA__>
217 in the module, _not_ the data after the C<__END__> token in the 'main'
218 program, since the compiler encounters the 'require'd file later.
220 =head2 SelfLoader autoloading
222 The B<SelfLoader> works by the user placing the C<__DATA__>
223 token I<after> perl code which needs to be compiled and
224 run at 'require' time, but I<before> subroutine declarations
225 that can be loaded in later - usually because they may never
228 The B<SelfLoader> will read from the FOOBAR::DATA filehandle to
229 load in the data after C<__DATA__>, and load in any subroutine
230 when it is called. The costs are the one-time parsing of the
231 data after C<__DATA__>, and a load delay for the _first_
232 call of any autoloaded function. The benefits (hopefully)
233 are a speeded up compilation phase, with no need to load
234 functions which are never used.
236 The B<SelfLoader> will stop reading from C<__DATA__> if
237 it encounters the C<__END__> token - just as you would expect.
238 If the C<__END__> token is present, and is followed by the
239 token DATA, then the B<SelfLoader> leaves the FOOBAR::DATA
240 filehandle open on the line after that token.
242 The B<SelfLoader> exports the C<AUTOLOAD> subroutine to the
243 package using the B<SelfLoader>, and this loads the called
244 subroutine when it is first called.
246 There is no advantage to putting subroutines which will _always_
247 be called after the C<__DATA__> token.
249 =head2 Autoloading and package lexicals
251 A 'my $pack_lexical' statement makes the variable $pack_lexical
252 local _only_ to the file up to the C<__DATA__> token. Subroutines
253 declared elsewhere _cannot_ see these types of variables,
254 just as if you declared subroutines in the package but in another
255 file, they cannot see these variables.
257 So specifically, autoloaded functions cannot see package
258 lexicals (this applies to both the B<SelfLoader> and the Autoloader).
259 The C<vars> pragma provides an alternative to defining package-level
260 globals that will be visible to autoloaded routines. See the documentation
261 on B<vars> in the pragma section of L<perlmod>.
263 =head2 SelfLoader and AutoLoader
265 The B<SelfLoader> can replace the AutoLoader - just change 'use AutoLoader'
266 to 'use SelfLoader' (though note that the B<SelfLoader> exports
267 the AUTOLOAD function - but if you have your own AUTOLOAD and
268 are using the AutoLoader too, you probably know what you're doing),
269 and the C<__END__> token to C<__DATA__>. You will need perl version 5.001m
270 or later to use this (version 5.001 with all patches up to patch m).
272 There is no need to inherit from the B<SelfLoader>.
274 The B<SelfLoader> works similarly to the AutoLoader, but picks up the
275 subs from after the C<__DATA__> instead of in the 'lib/auto' directory.
276 There is a maintenance gain in not needing to run AutoSplit on the module
277 at installation, and a runtime gain in not needing to keep opening and
278 closing files to load subs. There is a runtime loss in needing
279 to parse the code after the C<__DATA__>. Details of the B<AutoLoader> and
280 another view of these distinctions can be found in that module's
283 =head2 __DATA__, __END__, and the FOOBAR::DATA filehandle.
285 This section is only relevant if you want to use
286 the C<FOOBAR::DATA> together with the B<SelfLoader>.
288 Data after the C<__DATA__> token in a module is read using the
289 FOOBAR::DATA filehandle. C<__END__> can still be used to denote the end
290 of the C<__DATA__> section if followed by the token DATA - this is supported
291 by the B<SelfLoader>. The C<FOOBAR::DATA> filehandle is left open if an
292 C<__END__> followed by a DATA is found, with the filehandle positioned at
293 the start of the line after the C<__END__> token. If no C<__END__> token is
294 present, or an C<__END__> token with no DATA token on the same line, then
295 the filehandle is closed.
297 The B<SelfLoader> reads from wherever the current
298 position of the C<FOOBAR::DATA> filehandle is, until the
299 EOF or C<__END__>. This means that if you want to use
300 that filehandle (and ONLY if you want to), you should either
302 1. Put all your subroutine declarations immediately after
303 the C<__DATA__> token and put your own data after those
304 declarations, using the C<__END__> token to mark the end
305 of subroutine declarations. You must also ensure that the B<SelfLoader>
306 reads first by calling 'SelfLoader-E<gt>load_stubs();', or by using a
307 function which is selfloaded;
311 2. You should read the C<FOOBAR::DATA> filehandle first, leaving
312 the handle open and positioned at the first line of subroutine
315 You could conceivably do both.
317 =head2 Classes and inherited methods.
319 For modules which are not classes, this section is not relevant.
320 This section is only relevant if you have methods which could
323 A subroutine stub (or forward declaration) looks like
327 i.e. it is a subroutine declaration without the body of the
328 subroutine. For modules which are not classes, there is no real
329 need for stubs as far as autoloading is concerned.
331 For modules which ARE classes, and need to handle inherited methods,
332 stubs are needed to ensure that the method inheritance mechanism works
333 properly. You can load the stubs into the module at 'require' time, by
334 adding the statement 'SelfLoader-E<gt>load_stubs();' to the module to do
337 The alternative is to put the stubs in before the C<__DATA__> token BEFORE
338 releasing the module, and for this purpose the C<Devel::SelfStubber>
339 module is available. However this does require the extra step of ensuring
340 that the stubs are in the module. If this is done I strongly recommend
341 that this is done BEFORE releasing the module - it should NOT be done
342 at install time in general.
344 =head1 Multiple packages and fully qualified subroutine names
346 Subroutines in multiple packages within the same file are supported - but you
347 should note that this requires exporting the C<SelfLoader::AUTOLOAD> to
348 every package which requires it. This is done automatically by the
349 B<SelfLoader> when it first loads the subs into the cache, but you should
350 really specify it in the initialization before the C<__DATA__> by putting
351 a 'use SelfLoader' statement in each package.
353 Fully qualified subroutine names are also supported. For example,
360 will all be loaded correctly by the B<SelfLoader>, and the B<SelfLoader>
361 will ensure that the packages 'foo' and 'baz' correctly have the
362 B<SelfLoader> C<AUTOLOAD> method when the data after C<__DATA__> is first
367 C<SelfLoader> is maintained by the perl5-porters. Please direct
368 any questions to the canonical mailing list. Anything that
369 is applicable to the CPAN release can be sent to its maintainer,
372 Author and Maintainer: The Perl5-Porters <perl5-porters@perl.org>
374 Maintainer of the CPAN release: Steffen Mueller <smueller@cpan.org>
376 =head1 COPYRIGHT AND LICENSE
378 This package has been part of the perl core since the first release
379 of perl5. It has been released separately to CPAN so older installations
380 can benefit from bug fixes.
382 This package has the same copyright and license as the perl core:
384 Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999,
385 2000, 2001, 2002, 2003, 2004, 2005, 2006 by Larry Wall and others
389 This program is free software; you can redistribute it and/or modify
390 it under the terms of either:
392 a) the GNU General Public License as published by the Free
393 Software Foundation; either version 1, or (at your option) any
396 b) the "Artistic License" which comes with this Kit.
398 This program is distributed in the hope that it will be useful,
399 but WITHOUT ANY WARRANTY; without even the implied warranty of
400 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See either
401 the GNU General Public License or the Artistic License for more details.
403 You should have received a copy of the Artistic License with this
404 Kit, in the file named "Artistic". If not, I'll be glad to provide one.
406 You should also have received a copy of the GNU General Public License
407 along with this program in the file named "Copying". If not, write to the
408 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
409 02111-1307, USA or visit their web page on the internet at
410 http://www.gnu.org/copyleft/gpl.html.
412 For those of you that choose to use the GNU General Public License,
413 my interpretation of the GNU General Public License is that no Perl
414 script falls under the terms of the GPL unless you explicitly put
415 said script under the terms of the GPL yourself. Furthermore, any
416 object code linked with perl does not automatically fall under the
417 terms of the GPL, provided such object code only adds definitions
418 of subroutines and variables, and does not otherwise impair the
419 resulting interpreter from executing any standard Perl script. I
420 consider linking in C subroutines in this manner to be the moral
421 equivalent of defining subroutines in the Perl language itself. You
422 may sell such an object file as proprietary provided that you provide
423 or offer to provide the Perl source, as specified by the GNU General
424 Public License. (This is merely an alternate way of specifying input
425 to the program.) You may also sell a binary produced by the dumping of
426 a running Perl script that belongs to you, provided that you provide or
427 offer to provide the Perl source as specified by the GPL. (The
428 fact that a Perl interpreter and your code are in the same binary file
429 is, in this case, a form of mere aggregation.) This is my interpretation
430 of the GPL. If you still have concerns or difficulties understanding
431 my intent, feel free to contact me. Of course, the Artistic License
432 spells all this out for your protection, so you may prefer to use that.