7 # The following bit of eval-magic is necessary to make this work on
9 use vars qw/$AttrList/;
13 use 5.009005; # due to new regexp features
14 # allow checking for valid ': attrlist' attachments
22 (?<nested> \( (?: [^()]++ | (?&nested)++ )*+ \) ) ?
24 (?: \s* : \s* | \s+ (?! :) )
32 # allow checking for valid ': attrlist' attachments
33 # (we use 'our' rather than 'my' here, due to the rather complex and buggy
34 # behaviour of lexicals with qr// and (??{$lex}) )
36 $nested = qr{ \( (?: (?> [^()]+ ) | (??{ $nested }) )* \) }x;
37 our $one_attr = qr{ (?> (?! \d) \w+ (?:$nested)? ) (?:\s*\:\s*|\s+(?!\:)) }x;
38 $AttrList = qr{ \s* : \s* (?: $one_attr )* }x;
43 our @ISA = qw(Exporter);
44 our @EXPORT = qw(AUTOLOAD);
45 sub Version {$VERSION}
48 my %Cache; # private cache for all SelfLoader's client packages
50 # in croak and carp, protect $@ from "require Carp;" RT #40216
52 sub croak { { local $@; require Carp; } goto &Carp::croak }
53 sub carp { { local $@; require Carp; } goto &Carp::carp }
57 print STDERR "SelfLoader::AUTOLOAD for $AUTOLOAD\n" if DEBUG;
58 my $SL_code = $Cache{$AUTOLOAD};
59 my $save = $@; # evals in both AUTOLOAD and _load_stubs can corrupt $@
61 # Maybe this pack had stubs before __DATA__, and never initialized.
62 # Or, this maybe an automatic DESTROY method call when none exists.
63 $AUTOLOAD =~ m/^(.*)::/;
64 SelfLoader->_load_stubs($1) unless exists $Cache{"${1}::<DATA"};
65 $SL_code = $Cache{$AUTOLOAD};
66 $SL_code = "sub $AUTOLOAD { }"
67 if (!$SL_code and $AUTOLOAD =~ m/::DESTROY$/);
68 croak "Undefined subroutine $AUTOLOAD" unless $SL_code;
70 print STDERR "SelfLoader::AUTOLOAD eval: $SL_code\n" if DEBUG;
81 defined(&$AUTOLOAD) || die "SelfLoader inconsistency error";
82 delete $Cache{$AUTOLOAD};
86 sub load_stubs { shift->_load_stubs((caller)[0]) }
89 # $endlines is used by Devel::SelfStubber to capture lines after __END__
90 my($self, $callpack, $endlines) = @_;
92 my $fh = \*{"${callpack}::DATA"};
94 my $currpack = $callpack;
95 my($line,$name,@lines, @stubs, $protoype);
97 print STDERR "SelfLoader::load_stubs($callpack)\n" if DEBUG;
98 croak("$callpack doesn't contain an __DATA__ token")
99 unless defined fileno($fh);
100 # Protect: fork() shares the file pointer between the parent and the kid
101 if(sysseek($fh, tell($fh), 0)) {
102 open my $nfh, '<&', $fh or croak "reopen: $!";# dup() the fd
103 close $fh or die "close: $!"; # autocloses, but be paranoid
104 open $fh, '<&', $nfh or croak "reopen2: $!"; # dup() the fd "back"
105 close $nfh or die "close after reopen: $!"; # autocloses, but be paranoid
108 $Cache{"${currpack}::<DATA"} = 1; # indicate package is cached
111 while(defined($line = <$fh>) and $line !~ m/^__END__/) {
112 if ($line =~ m/^\s*sub\s+([\w:]+)\s*((?:\([\\\$\@\%\&\*\;]*\))?(?:$AttrList)?)/) {
113 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
116 if (index($1,'::') == -1) { # simple sub name
117 $name = "${currpack}::$1";
118 } else { # sub name with package
121 if (defined(&{"${1}::AUTOLOAD"})) {
122 \&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD ||
123 die 'SelfLoader Error: attempt to specify Selfloading',
124 " sub $name in non-selfloading module $1";
126 $self->export($1,'AUTOLOAD');
129 } elsif ($line =~ m/^package\s+([\w:]+)/) { # A package declared
130 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
131 $self->_package_defined($line);
135 $Cache{"${currpack}::<DATA"} = 1; # indicate package is cached
136 if (defined(&{"${1}::AUTOLOAD"})) {
137 \&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD ||
138 die 'SelfLoader Error: attempt to specify Selfloading',
139 " package $currpack which already has AUTOLOAD";
141 $self->export($currpack,'AUTOLOAD');
147 if (defined($line) && $line =~ /^__END__/) { # __END__
148 unless ($line =~ /^__END__\s*DATA/) {
150 # Devel::SelfStubber would like us to capture the lines after
151 # __END__ so it can write out the entire file
157 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype));
159 eval join('', @stubs) if @stubs;
164 my($self,$fullname,$pack,$lines, $protoype) = @_;
165 return () unless $fullname;
166 carp("Redefining sub $fullname")
167 if exists $Cache{$fullname};
168 $Cache{$fullname} = join('', "\n\#line 1 \"sub $fullname\"\npackage $pack; ", @$lines);
169 #$Cache{$fullname} = join('', "package $pack; ",@$lines);
170 print STDERR "SelfLoader cached $fullname: $Cache{$fullname}" if DEBUG;
171 # return stub to be eval'd
172 defined($protoype) ? "sub $fullname $protoype;" : "sub $fullname;"
175 sub _package_defined {}
182 SelfLoader - load functions only on demand
189 ... (initializing code)
197 This module tells its users that functions in the FOOBAR package are to be
198 autoloaded from after the C<__DATA__> token. See also
199 L<perlsub/"Autoloading">.
201 =head2 The __DATA__ token
203 The C<__DATA__> token tells the perl compiler that the perl code
204 for compilation is finished. Everything after the C<__DATA__> token
205 is available for reading via the filehandle FOOBAR::DATA,
206 where FOOBAR is the name of the current package when the C<__DATA__>
207 token is reached. This works just the same as C<__END__> does in
208 package 'main', but for other modules data after C<__END__> is not
209 automatically retrievable, whereas data after C<__DATA__> is.
210 The C<__DATA__> token is not recognized in versions of perl prior to
213 Note that it is possible to have C<__DATA__> tokens in the same package
214 in multiple files, and that the last C<__DATA__> token in a given
215 package that is encountered by the compiler is the one accessible
216 by the filehandle. This also applies to C<__END__> and main, i.e. if
217 the 'main' program has an C<__END__>, but a module 'require'd (_not_ 'use'd)
218 by that program has a 'package main;' declaration followed by an 'C<__DATA__>',
219 then the C<DATA> filehandle is set to access the data after the C<__DATA__>
220 in the module, _not_ the data after the C<__END__> token in the 'main'
221 program, since the compiler encounters the 'require'd file later.
223 =head2 SelfLoader autoloading
225 The B<SelfLoader> works by the user placing the C<__DATA__>
226 token I<after> perl code which needs to be compiled and
227 run at 'require' time, but I<before> subroutine declarations
228 that can be loaded in later - usually because they may never
231 The B<SelfLoader> will read from the FOOBAR::DATA filehandle to
232 load in the data after C<__DATA__>, and load in any subroutine
233 when it is called. The costs are the one-time parsing of the
234 data after C<__DATA__>, and a load delay for the _first_
235 call of any autoloaded function. The benefits (hopefully)
236 are a speeded up compilation phase, with no need to load
237 functions which are never used.
239 The B<SelfLoader> will stop reading from C<__DATA__> if
240 it encounters the C<__END__> token - just as you would expect.
241 If the C<__END__> token is present, and is followed by the
242 token DATA, then the B<SelfLoader> leaves the FOOBAR::DATA
243 filehandle open on the line after that token.
245 The B<SelfLoader> exports the C<AUTOLOAD> subroutine to the
246 package using the B<SelfLoader>, and this loads the called
247 subroutine when it is first called.
249 There is no advantage to putting subroutines which will _always_
250 be called after the C<__DATA__> token.
252 =head2 Autoloading and package lexicals
254 A 'my $pack_lexical' statement makes the variable $pack_lexical
255 local _only_ to the file up to the C<__DATA__> token. Subroutines
256 declared elsewhere _cannot_ see these types of variables,
257 just as if you declared subroutines in the package but in another
258 file, they cannot see these variables.
260 So specifically, autoloaded functions cannot see package
261 lexicals (this applies to both the B<SelfLoader> and the Autoloader).
262 The C<vars> pragma provides an alternative to defining package-level
263 globals that will be visible to autoloaded routines. See the documentation
264 on B<vars> in the pragma section of L<perlmod>.
266 =head2 SelfLoader and AutoLoader
268 The B<SelfLoader> can replace the AutoLoader - just change 'use AutoLoader'
269 to 'use SelfLoader' (though note that the B<SelfLoader> exports
270 the AUTOLOAD function - but if you have your own AUTOLOAD and
271 are using the AutoLoader too, you probably know what you're doing),
272 and the C<__END__> token to C<__DATA__>. You will need perl version 5.001m
273 or later to use this (version 5.001 with all patches up to patch m).
275 There is no need to inherit from the B<SelfLoader>.
277 The B<SelfLoader> works similarly to the AutoLoader, but picks up the
278 subs from after the C<__DATA__> instead of in the 'lib/auto' directory.
279 There is a maintenance gain in not needing to run AutoSplit on the module
280 at installation, and a runtime gain in not needing to keep opening and
281 closing files to load subs. There is a runtime loss in needing
282 to parse the code after the C<__DATA__>. Details of the B<AutoLoader> and
283 another view of these distinctions can be found in that module's
286 =head2 __DATA__, __END__, and the FOOBAR::DATA filehandle.
288 This section is only relevant if you want to use
289 the C<FOOBAR::DATA> together with the B<SelfLoader>.
291 Data after the C<__DATA__> token in a module is read using the
292 FOOBAR::DATA filehandle. C<__END__> can still be used to denote the end
293 of the C<__DATA__> section if followed by the token DATA - this is supported
294 by the B<SelfLoader>. The C<FOOBAR::DATA> filehandle is left open if an
295 C<__END__> followed by a DATA is found, with the filehandle positioned at
296 the start of the line after the C<__END__> token. If no C<__END__> token is
297 present, or an C<__END__> token with no DATA token on the same line, then
298 the filehandle is closed.
300 The B<SelfLoader> reads from wherever the current
301 position of the C<FOOBAR::DATA> filehandle is, until the
302 EOF or C<__END__>. This means that if you want to use
303 that filehandle (and ONLY if you want to), you should either
305 1. Put all your subroutine declarations immediately after
306 the C<__DATA__> token and put your own data after those
307 declarations, using the C<__END__> token to mark the end
308 of subroutine declarations. You must also ensure that the B<SelfLoader>
309 reads first by calling 'SelfLoader-E<gt>load_stubs();', or by using a
310 function which is selfloaded;
314 2. You should read the C<FOOBAR::DATA> filehandle first, leaving
315 the handle open and positioned at the first line of subroutine
318 You could conceivably do both.
320 =head2 Classes and inherited methods.
322 For modules which are not classes, this section is not relevant.
323 This section is only relevant if you have methods which could
326 A subroutine stub (or forward declaration) looks like
330 i.e. it is a subroutine declaration without the body of the
331 subroutine. For modules which are not classes, there is no real
332 need for stubs as far as autoloading is concerned.
334 For modules which ARE classes, and need to handle inherited methods,
335 stubs are needed to ensure that the method inheritance mechanism works
336 properly. You can load the stubs into the module at 'require' time, by
337 adding the statement 'SelfLoader-E<gt>load_stubs();' to the module to do
340 The alternative is to put the stubs in before the C<__DATA__> token BEFORE
341 releasing the module, and for this purpose the C<Devel::SelfStubber>
342 module is available. However this does require the extra step of ensuring
343 that the stubs are in the module. If this is done I strongly recommend
344 that this is done BEFORE releasing the module - it should NOT be done
345 at install time in general.
347 =head1 Multiple packages and fully qualified subroutine names
349 Subroutines in multiple packages within the same file are supported - but you
350 should note that this requires exporting the C<SelfLoader::AUTOLOAD> to
351 every package which requires it. This is done automatically by the
352 B<SelfLoader> when it first loads the subs into the cache, but you should
353 really specify it in the initialization before the C<__DATA__> by putting
354 a 'use SelfLoader' statement in each package.
356 Fully qualified subroutine names are also supported. For example,
363 will all be loaded correctly by the B<SelfLoader>, and the B<SelfLoader>
364 will ensure that the packages 'foo' and 'baz' correctly have the
365 B<SelfLoader> C<AUTOLOAD> method when the data after C<__DATA__> is first
370 C<SelfLoader> is maintained by the perl5-porters. Please direct
371 any questions to the canonical mailing list. Anything that
372 is applicable to the CPAN release can be sent to its maintainer,
375 Author and Maintainer: The Perl5-Porters <perl5-porters@perl.org>
377 Maintainer of the CPAN release: Steffen Mueller <smueller@cpan.org>
379 =head1 COPYRIGHT AND LICENSE
381 This package has been part of the perl core since the first release
382 of perl5. It has been released separately to CPAN so older installations
383 can benefit from bug fixes.
385 This package has the same copyright and license as the perl core:
387 Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999,
388 2000, 2001, 2002, 2003, 2004, 2005, 2006 by Larry Wall and others
392 This program is free software; you can redistribute it and/or modify
393 it under the terms of either:
395 a) the GNU General Public License as published by the Free
396 Software Foundation; either version 1, or (at your option) any
399 b) the "Artistic License" which comes with this Kit.
401 This program is distributed in the hope that it will be useful,
402 but WITHOUT ANY WARRANTY; without even the implied warranty of
403 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See either
404 the GNU General Public License or the Artistic License for more details.
406 You should have received a copy of the Artistic License with this
407 Kit, in the file named "Artistic". If not, I'll be glad to provide one.
409 You should also have received a copy of the GNU General Public License
410 along with this program in the file named "Copying". If not, write to the
411 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
412 02111-1307, USA or visit their web page on the internet at
413 http://www.gnu.org/copyleft/gpl.html.
415 For those of you that choose to use the GNU General Public License,
416 my interpretation of the GNU General Public License is that no Perl
417 script falls under the terms of the GPL unless you explicitly put
418 said script under the terms of the GPL yourself. Furthermore, any
419 object code linked with perl does not automatically fall under the
420 terms of the GPL, provided such object code only adds definitions
421 of subroutines and variables, and does not otherwise impair the
422 resulting interpreter from executing any standard Perl script. I
423 consider linking in C subroutines in this manner to be the moral
424 equivalent of defining subroutines in the Perl language itself. You
425 may sell such an object file as proprietary provided that you provide
426 or offer to provide the Perl source, as specified by the GNU General
427 Public License. (This is merely an alternate way of specifying input
428 to the program.) You may also sell a binary produced by the dumping of
429 a running Perl script that belongs to you, provided that you provide or
430 offer to provide the Perl source as specified by the GPL. (The
431 fact that a Perl interpreter and your code are in the same binary file
432 is, in this case, a form of mere aggregation.) This is my interpretation
433 of the GPL. If you still have concerns or difficulties understanding
434 my intent, feel free to contact me. Of course, the Artistic License
435 spells all this out for your protection, so you may prefer to use that.