1package SelfLoader; 2use 5.008; 3use strict; 4use IO::Handle; 5our $VERSION = "1.21"; 6 7# The following bit of eval-magic is necessary to make this work on 8# perls < 5.009005. 9use vars qw/$AttrList/; 10BEGIN { 11 if ($] > 5.009004) { 12 eval <<'NEWERPERL'; 13use 5.009005; # due to new regexp features 14# allow checking for valid ': attrlist' attachments 15# see also AutoSplit 16$AttrList = qr{ 17 \s* : \s* 18 (?: 19 # one attribute 20 (?> # no backtrack 21 (?! \d) \w+ 22 (?<nested> \( (?: [^()]++ | (?&nested)++ )*+ \) ) ? 23 ) 24 (?: \s* : \s* | \s+ (?! :) ) 25 )* 26}x; 27 28NEWERPERL 29 } 30 else { 31 eval <<'OLDERPERL'; 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}) ) 35our $nested; 36$nested = qr{ \( (?: (?> [^()]+ ) | (??{ $nested }) )* \) }x; 37our $one_attr = qr{ (?> (?! \d) \w+ (?:$nested)? ) (?:\s*\:\s*|\s+(?!\:)) }x; 38$AttrList = qr{ \s* : \s* (?: $one_attr )* }x; 39OLDERPERL 40 } 41} 42use Exporter; 43our @ISA = qw(Exporter); 44our @EXPORT = qw(AUTOLOAD); 45sub Version {$VERSION} 46sub DEBUG () { 0 } 47 48my %Cache; # private cache for all SelfLoader's client packages 49 50# in croak and carp, protect $@ from "require Carp;" RT #40216 51 52sub croak { { local $@; require Carp; } goto &Carp::croak } 53sub carp { { local $@; require Carp; } goto &Carp::carp } 54 55AUTOLOAD { 56 our $AUTOLOAD; 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 $@ 60 unless ($SL_code) { 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; 69 } 70 print STDERR "SelfLoader::AUTOLOAD eval: $SL_code\n" if DEBUG; 71 72 { 73 no strict; 74 eval $SL_code; 75 } 76 if ($@) { 77 $@ =~ s/ at .*\n//; 78 croak $@; 79 } 80 $@ = $save; 81 defined(&$AUTOLOAD) || die "SelfLoader inconsistency error"; 82 delete $Cache{$AUTOLOAD}; 83 goto &$AUTOLOAD 84} 85 86sub load_stubs { shift->_load_stubs((caller)[0]) } 87 88sub _load_stubs { 89 # $endlines is used by Devel::SelfStubber to capture lines after __END__ 90 my($self, $callpack, $endlines) = @_; 91 no strict "refs"; 92 my $fh = \*{"${callpack}::DATA"}; 93 use strict; 94 my $currpack = $callpack; 95 my($line,$name,@lines, @stubs, $protoype); 96 97 print STDERR "SelfLoader::load_stubs($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 106 $fh->untaint; 107 } 108 $Cache{"${currpack}::<DATA"} = 1; # indicate package is cached 109 110 local($/) = "\n"; 111 while(defined($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)); 114 $protoype = $2; 115 @lines = ($line); 116 if (index($1,'::') == -1) { # simple sub name 117 $name = "${currpack}::$1"; 118 } else { # sub name with package 119 $name = $1; 120 $name =~ m/^(.*)::/; 121 if (defined(&{"${1}::AUTOLOAD"})) { 122 \&{"${1}::AUTOLOAD"} == \&SelfLoader::AUTOLOAD || 123 die 'SelfLoader Error: attempt to specify Selfloading', 124 " sub $name in non-selfloading module $1"; 125 } else { 126 $self->export($1,'AUTOLOAD'); 127 } 128 } 129 } elsif ($line =~ m/^package\s+([\w:]+)/) { # A package declared 130 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype)); 131 $self->_package_defined($line); 132 $name = ''; 133 @lines = (); 134 $currpack = $1; 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"; 140 } else { 141 $self->export($currpack,'AUTOLOAD'); 142 } 143 } else { 144 push(@lines,$line); 145 } 146 } 147 if (defined($line) && $line =~ /^__END__/) { # __END__ 148 unless ($line =~ /^__END__\s*DATA/) { 149 if ($endlines) { 150 # Devel::SelfStubber would like us to capture the lines after 151 # __END__ so it can write out the entire file 152 @$endlines = <$fh>; 153 } 154 close($fh); 155 } 156 } 157 push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype)); 158 no strict; 159 eval join('', @stubs) if @stubs; 160} 161 162 163sub _add_to_cache { 164 my($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;" 173} 174 175sub _package_defined {} 176 1771; 178__END__ 179 180=head1 NAME 181 182SelfLoader - load functions only on demand 183 184=head1 SYNOPSIS 185 186 package FOOBAR; 187 use SelfLoader; 188 189 ... (initializing code) 190 191 __DATA__ 192 sub {.... 193 194 195=head1 DESCRIPTION 196 197This module tells its users that functions in the FOOBAR package are to be 198autoloaded from after the C<__DATA__> token. See also 199L<perlsub/"Autoloading">. 200 201=head2 The __DATA__ token 202 203The C<__DATA__> token tells the perl compiler that the perl code 204for compilation is finished. Everything after the C<__DATA__> token 205is available for reading via the filehandle FOOBAR::DATA, 206where FOOBAR is the name of the current package when the C<__DATA__> 207token is reached. This works just the same as C<__END__> does in 208package 'main', but for other modules data after C<__END__> is not 209automatically retrievable, whereas data after C<__DATA__> is. 210The C<__DATA__> token is not recognized in versions of perl prior to 2115.001m. 212 213Note that it is possible to have C<__DATA__> tokens in the same package 214in multiple files, and that the last C<__DATA__> token in a given 215package that is encountered by the compiler is the one accessible 216by the filehandle. This also applies to C<__END__> and main, i.e. if 217the 'main' program has an C<__END__>, but a module 'require'd (_not_ 'use'd) 218by that program has a 'package main;' declaration followed by an 'C<__DATA__>', 219then the C<DATA> filehandle is set to access the data after the C<__DATA__> 220in the module, _not_ the data after the C<__END__> token in the 'main' 221program, since the compiler encounters the 'require'd file later. 222 223=head2 SelfLoader autoloading 224 225The B<SelfLoader> works by the user placing the C<__DATA__> 226token I<after> perl code which needs to be compiled and 227run at 'require' time, but I<before> subroutine declarations 228that can be loaded in later - usually because they may never 229be called. 230 231The B<SelfLoader> will read from the FOOBAR::DATA filehandle to 232load in the data after C<__DATA__>, and load in any subroutine 233when it is called. The costs are the one-time parsing of the 234data after C<__DATA__>, and a load delay for the _first_ 235call of any autoloaded function. The benefits (hopefully) 236are a speeded up compilation phase, with no need to load 237functions which are never used. 238 239The B<SelfLoader> will stop reading from C<__DATA__> if 240it encounters the C<__END__> token - just as you would expect. 241If the C<__END__> token is present, and is followed by the 242token DATA, then the B<SelfLoader> leaves the FOOBAR::DATA 243filehandle open on the line after that token. 244 245The B<SelfLoader> exports the C<AUTOLOAD> subroutine to the 246package using the B<SelfLoader>, and this loads the called 247subroutine when it is first called. 248 249There is no advantage to putting subroutines which will _always_ 250be called after the C<__DATA__> token. 251 252=head2 Autoloading and package lexicals 253 254A 'my $pack_lexical' statement makes the variable $pack_lexical 255local _only_ to the file up to the C<__DATA__> token. Subroutines 256declared elsewhere _cannot_ see these types of variables, 257just as if you declared subroutines in the package but in another 258file, they cannot see these variables. 259 260So specifically, autoloaded functions cannot see package 261lexicals (this applies to both the B<SelfLoader> and the Autoloader). 262The C<vars> pragma provides an alternative to defining package-level 263globals that will be visible to autoloaded routines. See the documentation 264on B<vars> in the pragma section of L<perlmod>. 265 266=head2 SelfLoader and AutoLoader 267 268The B<SelfLoader> can replace the AutoLoader - just change 'use AutoLoader' 269to 'use SelfLoader' (though note that the B<SelfLoader> exports 270the AUTOLOAD function - but if you have your own AUTOLOAD and 271are using the AutoLoader too, you probably know what you're doing), 272and the C<__END__> token to C<__DATA__>. You will need perl version 5.001m 273or later to use this (version 5.001 with all patches up to patch m). 274 275There is no need to inherit from the B<SelfLoader>. 276 277The B<SelfLoader> works similarly to the AutoLoader, but picks up the 278subs from after the C<__DATA__> instead of in the 'lib/auto' directory. 279There is a maintenance gain in not needing to run AutoSplit on the module 280at installation, and a runtime gain in not needing to keep opening and 281closing files to load subs. There is a runtime loss in needing 282to parse the code after the C<__DATA__>. Details of the B<AutoLoader> and 283another view of these distinctions can be found in that module's 284documentation. 285 286=head2 __DATA__, __END__, and the FOOBAR::DATA filehandle. 287 288This section is only relevant if you want to use 289the C<FOOBAR::DATA> together with the B<SelfLoader>. 290 291Data after the C<__DATA__> token in a module is read using the 292FOOBAR::DATA filehandle. C<__END__> can still be used to denote the end 293of the C<__DATA__> section if followed by the token DATA - this is supported 294by the B<SelfLoader>. The C<FOOBAR::DATA> filehandle is left open if an 295C<__END__> followed by a DATA is found, with the filehandle positioned at 296the start of the line after the C<__END__> token. If no C<__END__> token is 297present, or an C<__END__> token with no DATA token on the same line, then 298the filehandle is closed. 299 300The B<SelfLoader> reads from wherever the current 301position of the C<FOOBAR::DATA> filehandle is, until the 302EOF or C<__END__>. This means that if you want to use 303that filehandle (and ONLY if you want to), you should either 304 3051. Put all your subroutine declarations immediately after 306the C<__DATA__> token and put your own data after those 307declarations, using the C<__END__> token to mark the end 308of subroutine declarations. You must also ensure that the B<SelfLoader> 309reads first by calling 'SelfLoader-E<gt>load_stubs();', or by using a 310function which is selfloaded; 311 312or 313 3142. You should read the C<FOOBAR::DATA> filehandle first, leaving 315the handle open and positioned at the first line of subroutine 316declarations. 317 318You could conceivably do both. 319 320=head2 Classes and inherited methods. 321 322For modules which are not classes, this section is not relevant. 323This section is only relevant if you have methods which could 324be inherited. 325 326A subroutine stub (or forward declaration) looks like 327 328 sub stub; 329 330i.e. it is a subroutine declaration without the body of the 331subroutine. For modules which are not classes, there is no real 332need for stubs as far as autoloading is concerned. 333 334For modules which ARE classes, and need to handle inherited methods, 335stubs are needed to ensure that the method inheritance mechanism works 336properly. You can load the stubs into the module at 'require' time, by 337adding the statement 'SelfLoader-E<gt>load_stubs();' to the module to do 338this. 339 340The alternative is to put the stubs in before the C<__DATA__> token BEFORE 341releasing the module, and for this purpose the C<Devel::SelfStubber> 342module is available. However this does require the extra step of ensuring 343that the stubs are in the module. If this is done I strongly recommend 344that this is done BEFORE releasing the module - it should NOT be done 345at install time in general. 346 347=head1 Multiple packages and fully qualified subroutine names 348 349Subroutines in multiple packages within the same file are supported - but you 350should note that this requires exporting the C<SelfLoader::AUTOLOAD> to 351every package which requires it. This is done automatically by the 352B<SelfLoader> when it first loads the subs into the cache, but you should 353really specify it in the initialization before the C<__DATA__> by putting 354a 'use SelfLoader' statement in each package. 355 356Fully qualified subroutine names are also supported. For example, 357 358 __DATA__ 359 sub foo::bar {23} 360 package baz; 361 sub dob {32} 362 363will all be loaded correctly by the B<SelfLoader>, and the B<SelfLoader> 364will ensure that the packages 'foo' and 'baz' correctly have the 365B<SelfLoader> C<AUTOLOAD> method when the data after C<__DATA__> is first 366parsed. 367 368=head1 AUTHOR 369 370C<SelfLoader> is maintained by the perl5-porters. Please direct 371any questions to the canonical mailing list. Anything that 372is applicable to the CPAN release can be sent to its maintainer, 373though. 374 375Author and Maintainer: The Perl5-Porters <perl5-porters@perl.org> 376 377Maintainer of the CPAN release: Steffen Mueller <smueller@cpan.org> 378 379=head1 COPYRIGHT AND LICENSE 380 381This package has been part of the perl core since the first release 382of perl5. It has been released separately to CPAN so older installations 383can benefit from bug fixes. 384 385This package has the same copyright and license as the perl core: 386 387 Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 388 2000, 2001, 2002, 2003, 2004, 2005, 2006 by Larry Wall and others 389 390 All rights reserved. 391 392 This program is free software; you can redistribute it and/or modify 393 it under the terms of either: 394 395 a) the GNU General Public License as published by the Free 396 Software Foundation; either version 1, or (at your option) any 397 later version, or 398 399 b) the "Artistic License" which comes with this Kit. 400 401 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. 405 406 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. 408 409 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., 51 Franklin St, Fifth Floor, Boston, 412 MA 02110-1301, USA or visit their web page on the internet at 413 http://www.gnu.org/copyleft/gpl.html. 414 415 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. 436 437=cut 438