1package SelfLoader; 2use 5.008; 3use strict; 4our $VERSION = "1.17"; 5 6# The following bit of eval-magic is necessary to make this work on 7# perls < 5.009005. 8use vars qw/$AttrList/; 9BEGIN { 10 if ($] > 5.009004) { 11 eval <<'NEWERPERL'; 12use 5.009005; # due to new regexp features 13# allow checking for valid ': attrlist' attachments 14# see also AutoSplit 15$AttrList = qr{ 16 \s* : \s* 17 (?: 18 # one attribute 19 (?> # no backtrack 20 (?! \d) \w+ 21 (?<nested> \( (?: [^()]++ | (?&nested)++ )*+ \) ) ? 22 ) 23 (?: \s* : \s* | \s+ (?! :) ) 24 )* 25}x; 26 27NEWERPERL 28 } 29 else { 30 eval <<'OLDERPERL'; 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}) ) 34our $nested; 35$nested = qr{ \( (?: (?> [^()]+ ) | (??{ $nested }) )* \) }x; 36our $one_attr = qr{ (?> (?! \d) \w+ (?:$nested)? ) (?:\s*\:\s*|\s+(?!\:)) }x; 37$AttrList = qr{ \s* : \s* (?: $one_attr )* }x; 38OLDERPERL 39 } 40} 41use Exporter; 42our @ISA = qw(Exporter); 43our @EXPORT = qw(AUTOLOAD); 44sub Version {$VERSION} 45sub DEBUG () { 0 } 46 47my %Cache; # private cache for all SelfLoader's client packages 48 49# in croak and carp, protect $@ from "require Carp;" RT #40216 50 51sub croak { { local $@; require Carp; } goto &Carp::croak } 52sub carp { { local $@; require Carp; } goto &Carp::carp } 53 54AUTOLOAD { 55 our $AUTOLOAD; 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 $@ 59 unless ($SL_code) { 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; 68 } 69 print STDERR "SelfLoader::AUTOLOAD eval: $SL_code\n" if DEBUG; 70 71 { 72 no strict; 73 eval $SL_code; 74 } 75 if ($@) { 76 $@ =~ s/ at .*\n//; 77 croak $@; 78 } 79 $@ = $save; 80 defined(&$AUTOLOAD) || die "SelfLoader inconsistency error"; 81 delete $Cache{$AUTOLOAD}; 82 goto &$AUTOLOAD 83} 84 85sub load_stubs { shift->_load_stubs((caller)[0]) } 86 87sub _load_stubs { 88 # $endlines is used by Devel::SelfStubber to capture lines after __END__ 89 my($self, $callpack, $endlines) = @_; 90 no strict "refs"; 91 my $fh = \*{"${callpack}::DATA"}; 92 use strict; 93 my $currpack = $callpack; 94 my($line,$name,@lines, @stubs, $protoype); 95 96 print STDERR "SelfLoader::load_stubs($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: $!"; # autocloses, but be paranoid 103 open $fh, '<&', $nfh or croak "reopen2: $!"; # dup() the fd "back" 104 close $nfh or die "close after reopen: $!"; # autocloses, but be paranoid 105 } 106 $Cache{"${currpack}::<DATA"} = 1; # indicate package is cached 107 108 local($/) = "\n"; 109 while(defined($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)); 112 $protoype = $2; 113 @lines = ($line); 114 if (index($1,'::') == -1) { # simple sub name 115 $name = "${currpack}::$1"; 116 } else { # sub name with package 117 $name = $1; 118 $name =~ m/^(.*)::/; 119 if (defined(&{"${1}::AUTOLOAD"})) { 120 \&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD || 121 die 'SelfLoader Error: attempt to specify Selfloading', 122 " sub $name in non-selfloading module $1"; 123 } else { 124 $self->export($1,'AUTOLOAD'); 125 } 126 } 127 } elsif ($line =~ m/^package\s+([\w:]+)/) { # A package declared 128 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype)); 129 $self->_package_defined($line); 130 $name = ''; 131 @lines = (); 132 $currpack = $1; 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"; 138 } else { 139 $self->export($currpack,'AUTOLOAD'); 140 } 141 } else { 142 push(@lines,$line); 143 } 144 } 145 if (defined($line) && $line =~ /^__END__/) { # __END__ 146 unless ($line =~ /^__END__\s*DATA/) { 147 if ($endlines) { 148 # Devel::SelfStubber would like us to capture the lines after 149 # __END__ so it can write out the entire file 150 @$endlines = <$fh>; 151 } 152 close($fh); 153 } 154 } 155 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype)); 156 no strict; 157 eval join('', @stubs) if @stubs; 158} 159 160 161sub _add_to_cache { 162 my($self,$fullname,$pack,$lines, $protoype) = @_; 163 return () unless $fullname; 164 carp("Redefining sub $fullname") 165 if exists $Cache{$fullname}; 166 $Cache{$fullname} = join('', "\n\#line 1 \"sub $fullname\"\npackage $pack; ", @$lines); 167 #$Cache{$fullname} = join('', "package $pack; ",@$lines); 168 print STDERR "SelfLoader cached $fullname: $Cache{$fullname}" if DEBUG; 169 # return stub to be eval'd 170 defined($protoype) ? "sub $fullname $protoype;" : "sub $fullname;" 171} 172 173sub _package_defined {} 174 1751; 176__END__ 177 178=head1 NAME 179 180SelfLoader - load functions only on demand 181 182=head1 SYNOPSIS 183 184 package FOOBAR; 185 use SelfLoader; 186 187 ... (initializing code) 188 189 __DATA__ 190 sub {.... 191 192 193=head1 DESCRIPTION 194 195This module tells its users that functions in the FOOBAR package are to be 196autoloaded from after the C<__DATA__> token. See also 197L<perlsub/"Autoloading">. 198 199=head2 The __DATA__ token 200 201The C<__DATA__> token tells the perl compiler that the perl code 202for compilation is finished. Everything after the C<__DATA__> token 203is available for reading via the filehandle FOOBAR::DATA, 204where FOOBAR is the name of the current package when the C<__DATA__> 205token is reached. This works just the same as C<__END__> does in 206package 'main', but for other modules data after C<__END__> is not 207automatically retrievable, whereas data after C<__DATA__> is. 208The C<__DATA__> token is not recognized in versions of perl prior to 2095.001m. 210 211Note that it is possible to have C<__DATA__> tokens in the same package 212in multiple files, and that the last C<__DATA__> token in a given 213package that is encountered by the compiler is the one accessible 214by the filehandle. This also applies to C<__END__> and main, i.e. if 215the 'main' program has an C<__END__>, but a module 'require'd (_not_ 'use'd) 216by that program has a 'package main;' declaration followed by an 'C<__DATA__>', 217then the C<DATA> filehandle is set to access the data after the C<__DATA__> 218in the module, _not_ the data after the C<__END__> token in the 'main' 219program, since the compiler encounters the 'require'd file later. 220 221=head2 SelfLoader autoloading 222 223The B<SelfLoader> works by the user placing the C<__DATA__> 224token I<after> perl code which needs to be compiled and 225run at 'require' time, but I<before> subroutine declarations 226that can be loaded in later - usually because they may never 227be called. 228 229The B<SelfLoader> will read from the FOOBAR::DATA filehandle to 230load in the data after C<__DATA__>, and load in any subroutine 231when it is called. The costs are the one-time parsing of the 232data after C<__DATA__>, and a load delay for the _first_ 233call of any autoloaded function. The benefits (hopefully) 234are a speeded up compilation phase, with no need to load 235functions which are never used. 236 237The B<SelfLoader> will stop reading from C<__DATA__> if 238it encounters the C<__END__> token - just as you would expect. 239If the C<__END__> token is present, and is followed by the 240token DATA, then the B<SelfLoader> leaves the FOOBAR::DATA 241filehandle open on the line after that token. 242 243The B<SelfLoader> exports the C<AUTOLOAD> subroutine to the 244package using the B<SelfLoader>, and this loads the called 245subroutine when it is first called. 246 247There is no advantage to putting subroutines which will _always_ 248be called after the C<__DATA__> token. 249 250=head2 Autoloading and package lexicals 251 252A 'my $pack_lexical' statement makes the variable $pack_lexical 253local _only_ to the file up to the C<__DATA__> token. Subroutines 254declared elsewhere _cannot_ see these types of variables, 255just as if you declared subroutines in the package but in another 256file, they cannot see these variables. 257 258So specifically, autoloaded functions cannot see package 259lexicals (this applies to both the B<SelfLoader> and the Autoloader). 260The C<vars> pragma provides an alternative to defining package-level 261globals that will be visible to autoloaded routines. See the documentation 262on B<vars> in the pragma section of L<perlmod>. 263 264=head2 SelfLoader and AutoLoader 265 266The B<SelfLoader> can replace the AutoLoader - just change 'use AutoLoader' 267to 'use SelfLoader' (though note that the B<SelfLoader> exports 268the AUTOLOAD function - but if you have your own AUTOLOAD and 269are using the AutoLoader too, you probably know what you're doing), 270and the C<__END__> token to C<__DATA__>. You will need perl version 5.001m 271or later to use this (version 5.001 with all patches up to patch m). 272 273There is no need to inherit from the B<SelfLoader>. 274 275The B<SelfLoader> works similarly to the AutoLoader, but picks up the 276subs from after the C<__DATA__> instead of in the 'lib/auto' directory. 277There is a maintenance gain in not needing to run AutoSplit on the module 278at installation, and a runtime gain in not needing to keep opening and 279closing files to load subs. There is a runtime loss in needing 280to parse the code after the C<__DATA__>. Details of the B<AutoLoader> and 281another view of these distinctions can be found in that module's 282documentation. 283 284=head2 __DATA__, __END__, and the FOOBAR::DATA filehandle. 285 286This section is only relevant if you want to use 287the C<FOOBAR::DATA> together with the B<SelfLoader>. 288 289Data after the C<__DATA__> token in a module is read using the 290FOOBAR::DATA filehandle. C<__END__> can still be used to denote the end 291of the C<__DATA__> section if followed by the token DATA - this is supported 292by the B<SelfLoader>. The C<FOOBAR::DATA> filehandle is left open if an 293C<__END__> followed by a DATA is found, with the filehandle positioned at 294the start of the line after the C<__END__> token. If no C<__END__> token is 295present, or an C<__END__> token with no DATA token on the same line, then 296the filehandle is closed. 297 298The B<SelfLoader> reads from wherever the current 299position of the C<FOOBAR::DATA> filehandle is, until the 300EOF or C<__END__>. This means that if you want to use 301that filehandle (and ONLY if you want to), you should either 302 3031. Put all your subroutine declarations immediately after 304the C<__DATA__> token and put your own data after those 305declarations, using the C<__END__> token to mark the end 306of subroutine declarations. You must also ensure that the B<SelfLoader> 307reads first by calling 'SelfLoader-E<gt>load_stubs();', or by using a 308function which is selfloaded; 309 310or 311 3122. You should read the C<FOOBAR::DATA> filehandle first, leaving 313the handle open and positioned at the first line of subroutine 314declarations. 315 316You could conceivably do both. 317 318=head2 Classes and inherited methods. 319 320For modules which are not classes, this section is not relevant. 321This section is only relevant if you have methods which could 322be inherited. 323 324A subroutine stub (or forward declaration) looks like 325 326 sub stub; 327 328i.e. it is a subroutine declaration without the body of the 329subroutine. For modules which are not classes, there is no real 330need for stubs as far as autoloading is concerned. 331 332For modules which ARE classes, and need to handle inherited methods, 333stubs are needed to ensure that the method inheritance mechanism works 334properly. You can load the stubs into the module at 'require' time, by 335adding the statement 'SelfLoader-E<gt>load_stubs();' to the module to do 336this. 337 338The alternative is to put the stubs in before the C<__DATA__> token BEFORE 339releasing the module, and for this purpose the C<Devel::SelfStubber> 340module is available. However this does require the extra step of ensuring 341that the stubs are in the module. If this is done I strongly recommend 342that this is done BEFORE releasing the module - it should NOT be done 343at install time in general. 344 345=head1 Multiple packages and fully qualified subroutine names 346 347Subroutines in multiple packages within the same file are supported - but you 348should note that this requires exporting the C<SelfLoader::AUTOLOAD> to 349every package which requires it. This is done automatically by the 350B<SelfLoader> when it first loads the subs into the cache, but you should 351really specify it in the initialization before the C<__DATA__> by putting 352a 'use SelfLoader' statement in each package. 353 354Fully qualified subroutine names are also supported. For example, 355 356 __DATA__ 357 sub foo::bar {23} 358 package baz; 359 sub dob {32} 360 361will all be loaded correctly by the B<SelfLoader>, and the B<SelfLoader> 362will ensure that the packages 'foo' and 'baz' correctly have the 363B<SelfLoader> C<AUTOLOAD> method when the data after C<__DATA__> is first 364parsed. 365 366=head1 AUTHOR 367 368C<SelfLoader> is maintained by the perl5-porters. Please direct 369any questions to the canonical mailing list. Anything that 370is applicable to the CPAN release can be sent to its maintainer, 371though. 372 373Author and Maintainer: The Perl5-Porters <perl5-porters@perl.org> 374 375Maintainer of the CPAN release: Steffen Mueller <smueller@cpan.org> 376 377=head1 COPYRIGHT AND LICENSE 378 379This package has been part of the perl core since the first release 380of perl5. It has been released separately to CPAN so older installations 381can benefit from bug fixes. 382 383This package has the same copyright and license as the perl core: 384 385 Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 386 2000, 2001, 2002, 2003, 2004, 2005, 2006 by Larry Wall and others 387 388 All rights reserved. 389 390 This program is free software; you can redistribute it and/or modify 391 it under the terms of either: 392 393 a) the GNU General Public License as published by the Free 394 Software Foundation; either version 1, or (at your option) any 395 later version, or 396 397 b) the "Artistic License" which comes with this Kit. 398 399 This program is distributed in the hope that it will be useful, 400 but WITHOUT ANY WARRANTY; without even the implied warranty of 401 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See either 402 the GNU General Public License or the Artistic License for more details. 403 404 You should have received a copy of the Artistic License with this 405 Kit, in the file named "Artistic". If not, I'll be glad to provide one. 406 407 You should also have received a copy of the GNU General Public License 408 along with this program in the file named "Copying". If not, write to the 409 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 410 02111-1307, USA or visit their web page on the internet at 411 http://www.gnu.org/copyleft/gpl.html. 412 413 For those of you that choose to use the GNU General Public License, 414 my interpretation of the GNU General Public License is that no Perl 415 script falls under the terms of the GPL unless you explicitly put 416 said script under the terms of the GPL yourself. Furthermore, any 417 object code linked with perl does not automatically fall under the 418 terms of the GPL, provided such object code only adds definitions 419 of subroutines and variables, and does not otherwise impair the 420 resulting interpreter from executing any standard Perl script. I 421 consider linking in C subroutines in this manner to be the moral 422 equivalent of defining subroutines in the Perl language itself. You 423 may sell such an object file as proprietary provided that you provide 424 or offer to provide the Perl source, as specified by the GNU General 425 Public License. (This is merely an alternate way of specifying input 426 to the program.) You may also sell a binary produced by the dumping of 427 a running Perl script that belongs to you, provided that you provide or 428 offer to provide the Perl source as specified by the GPL. (The 429 fact that a Perl interpreter and your code are in the same binary file 430 is, in this case, a form of mere aggregation.) This is my interpretation 431 of the GPL. If you still have concerns or difficulties understanding 432 my intent, feel free to contact me. Of course, the Artistic License 433 spells all this out for your protection, so you may prefer to use that. 434 435=cut 436