Commit | Line | Data |
8990e307 |
1 | package AutoLoader; |
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2 | |
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3 | use strict; |
3b825e41 |
4 | use 5.006_001; |
04c1a02b |
5 | |
6 | our($VERSION, $AUTOLOAD); |
f06db76b |
7 | |
adaafad2 |
8 | my $is_dosish; |
ed79a026 |
9 | my $is_epoc; |
adaafad2 |
10 | my $is_vms; |
084592ab |
11 | my $is_macos; |
adaafad2 |
12 | |
1be0b951 |
13 | BEGIN { |
2986a63f |
14 | $is_dosish = $^O eq 'dos' || $^O eq 'os2' || $^O eq 'MSWin32' || $^O eq 'NetWare'; |
ed79a026 |
15 | $is_epoc = $^O eq 'epoc'; |
adaafad2 |
16 | $is_vms = $^O eq 'VMS'; |
084592ab |
17 | $is_macos = $^O eq 'MacOS'; |
536daee0 |
18 | $VERSION = '5.64_01'; |
1be0b951 |
19 | } |
f06db76b |
20 | |
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21 | AUTOLOAD { |
7d4fbd98 |
22 | my $sub = $AUTOLOAD; |
00bb01c7 |
23 | my $filename = AutoLoader::find_filename( $sub ); |
24 | |
25 | my $save = $@; |
26 | local $!; # Do not munge the value. |
27 | eval { local $SIG{__DIE__}; require $filename }; |
28 | if ($@) { |
29 | if (substr($sub,-9) eq '::DESTROY') { |
30 | no strict 'refs'; |
31 | *$sub = sub {}; |
32 | $@ = undef; |
33 | } elsif ($@ =~ /^Can't locate/) { |
34 | # The load might just have failed because the filename was too |
35 | # long for some old SVR3 systems which treat long names as errors. |
36 | # If we can successfully truncate a long name then it's worth a go. |
37 | # There is a slight risk that we could pick up the wrong file here |
38 | # but autosplit should have warned about that when splitting. |
39 | if ($filename =~ s/(\w{12,})\.al$/substr($1,0,11).".al"/e){ |
40 | eval { local $SIG{__DIE__}; require $filename }; |
41 | } |
42 | } |
43 | if ($@){ |
44 | $@ =~ s/ at .*\n//; |
45 | my $error = $@; |
46 | require Carp; |
47 | Carp::croak($error); |
48 | } |
49 | } |
50 | $@ = $save; |
51 | goto &$sub; |
52 | } |
53 | |
00bb01c7 |
54 | sub find_filename { |
55 | my $sub = shift; |
7d4fbd98 |
56 | my $filename; |
5a556d17 |
57 | # Braces used to preserve $1 et al. |
58 | { |
adaafad2 |
59 | # Try to find the autoloaded file from the package-qualified |
60 | # name of the sub. e.g., if the sub needed is |
61 | # Getopt::Long::GetOptions(), then $INC{Getopt/Long.pm} is |
62 | # something like '/usr/lib/perl5/Getopt/Long.pm', and the |
63 | # autoload file is '/usr/lib/perl5/auto/Getopt/Long/GetOptions.al'. |
64 | # |
65 | # However, if @INC is a relative path, this might not work. If, |
66 | # for example, @INC = ('lib'), then $INC{Getopt/Long.pm} is |
67 | # 'lib/Getopt/Long.pm', and we want to require |
68 | # 'auto/Getopt/Long/GetOptions.al' (without the leading 'lib'). |
69 | # In this case, we simple prepend the 'auto/' and let the |
70 | # C<require> take care of the searching for us. |
71 | |
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72 | my ($pkg,$func) = ($sub =~ /(.*)::([^:]+)$/); |
adaafad2 |
73 | $pkg =~ s#::#/#g; |
7d4fbd98 |
74 | if (defined($filename = $INC{"$pkg.pm"})) { |
084592ab |
75 | if ($is_macos) { |
76 | $pkg =~ tr#/#:#; |
017a05de |
77 | $filename = undef |
78 | unless $filename =~ s#^(.*)$pkg\.pm\z#$1auto:$pkg:$func.al#s; |
084592ab |
79 | } else { |
017a05de |
80 | $filename = undef |
81 | unless $filename =~ s#^(.*)$pkg\.pm\z#$1auto/$pkg/$func.al#s; |
084592ab |
82 | } |
adaafad2 |
83 | |
84 | # if the file exists, then make sure that it is a |
85 | # a fully anchored path (i.e either '/usr/lib/auto/foo/bar.al', |
86 | # or './lib/auto/foo/bar.al'. This avoids C<require> searching |
87 | # (and failing) to find the 'lib/auto/foo/bar.al' because it |
88 | # looked for 'lib/lib/auto/foo/bar.al', given @INC = ('lib'). |
89 | |
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90 | if (defined $filename and -r $filename) { |
14a089c5 |
91 | unless ($filename =~ m|^/|s) { |
adaafad2 |
92 | if ($is_dosish) { |
14a089c5 |
93 | unless ($filename =~ m{^([a-z]:)?[\\/]}is) { |
00bb01c7 |
94 | if ($^O ne 'NetWare') { |
95 | $filename = "./$filename"; |
96 | } else { |
97 | $filename = "$filename"; |
98 | } |
adaafad2 |
99 | } |
100 | } |
ed79a026 |
101 | elsif ($is_epoc) { |
102 | unless ($filename =~ m{^([a-z?]:)?[\\/]}is) { |
103 | $filename = "./$filename"; |
104 | } |
4d6b4052 |
105 | } |
106 | elsif ($is_vms) { |
7d4fbd98 |
107 | # XXX todo by VMSmiths |
108 | $filename = "./$filename"; |
adaafad2 |
109 | } |
084592ab |
110 | elsif (!$is_macos) { |
7d4fbd98 |
111 | $filename = "./$filename"; |
adaafad2 |
112 | } |
113 | } |
114 | } |
115 | else { |
7d4fbd98 |
116 | $filename = undef; |
adaafad2 |
117 | } |
118 | } |
7d4fbd98 |
119 | unless (defined $filename) { |
adaafad2 |
120 | # let C<require> do the searching |
7d4fbd98 |
121 | $filename = "auto/$sub.al"; |
122 | $filename =~ s#::#/#g; |
adaafad2 |
123 | } |
5a556d17 |
124 | } |
00bb01c7 |
125 | return $filename; |
8990e307 |
126 | } |
1be0b951 |
127 | |
c2960299 |
128 | sub import { |
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129 | my $pkg = shift; |
130 | my $callpkg = caller; |
131 | |
132 | # |
133 | # Export symbols, but not by accident of inheritance. |
134 | # |
135 | |
e3d0cac0 |
136 | if ($pkg eq 'AutoLoader') { |
00bb01c7 |
137 | if ( @_ and $_[0] =~ /^&?AUTOLOAD$/ ) { |
138 | no strict 'refs'; |
139 | *{ $callpkg . '::AUTOLOAD' } = \&AUTOLOAD; |
00bb01c7 |
140 | } |
e3d0cac0 |
141 | } |
1be0b951 |
142 | |
143 | # |
c2960299 |
144 | # Try to find the autosplit index file. Eg., if the call package |
145 | # is POSIX, then $INC{POSIX.pm} is something like |
146 | # '/usr/local/lib/perl5/POSIX.pm', and the autosplit index file is in |
147 | # '/usr/local/lib/perl5/auto/POSIX/autosplit.ix', so we require that. |
148 | # |
149 | # However, if @INC is a relative path, this might not work. If, |
150 | # for example, @INC = ('lib'), then |
151 | # $INC{POSIX.pm} is 'lib/POSIX.pm', and we want to require |
152 | # 'auto/POSIX/autosplit.ix' (without the leading 'lib'). |
153 | # |
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154 | |
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155 | (my $calldir = $callpkg) =~ s#::#/#g; |
1be0b951 |
156 | my $path = $INC{$calldir . '.pm'}; |
157 | if (defined($path)) { |
c2960299 |
158 | # Try absolute path name. |
4d6b4052 |
159 | if ($is_macos) { |
160 | (my $malldir = $calldir) =~ tr#/#:#; |
161 | $path =~ s#^(.*)$malldir\.pm\z#$1auto:$malldir:autosplit.ix#s; |
162 | } else { |
163 | $path =~ s#^(.*)$calldir\.pm\z#$1auto/$calldir/autosplit.ix#; |
164 | } |
165 | |
c2960299 |
166 | eval { require $path; }; |
167 | # If that failed, try relative path with normal @INC searching. |
168 | if ($@) { |
1be0b951 |
169 | $path ="auto/$calldir/autosplit.ix"; |
c2960299 |
170 | eval { require $path; }; |
171 | } |
fb73857a |
172 | if ($@) { |
173 | my $error = $@; |
174 | require Carp; |
175 | Carp::carp($error); |
176 | } |
f06db76b |
177 | } |
f06db76b |
178 | } |
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179 | |
cb0cff20 |
180 | sub unimport { |
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181 | my $callpkg = caller; |
182 | |
183 | no strict 'refs'; |
00bb01c7 |
184 | |
536daee0 |
185 | for my $exported (qw( AUTOLOAD )) { |
00bb01c7 |
186 | my $symname = $callpkg . '::' . $exported; |
187 | undef *{ $symname } if \&{ $symname } == \&{ $exported }; |
188 | *{ $symname } = \&{ $symname }; |
189 | } |
cb0cff20 |
190 | } |
191 | |
8990e307 |
192 | 1; |
1be0b951 |
193 | |
194 | __END__ |
195 | |
196 | =head1 NAME |
197 | |
198 | AutoLoader - load subroutines only on demand |
199 | |
200 | =head1 SYNOPSIS |
201 | |
202 | package Foo; |
203 | use AutoLoader 'AUTOLOAD'; # import the default AUTOLOAD subroutine |
204 | |
205 | package Bar; |
206 | use AutoLoader; # don't import AUTOLOAD, define our own |
207 | sub AUTOLOAD { |
208 | ... |
209 | $AutoLoader::AUTOLOAD = "..."; |
210 | goto &AutoLoader::AUTOLOAD; |
211 | } |
212 | |
213 | =head1 DESCRIPTION |
214 | |
215 | The B<AutoLoader> module works with the B<AutoSplit> module and the |
216 | C<__END__> token to defer the loading of some subroutines until they are |
217 | used rather than loading them all at once. |
218 | |
219 | To use B<AutoLoader>, the author of a module has to place the |
220 | definitions of subroutines to be autoloaded after an C<__END__> token. |
221 | (See L<perldata>.) The B<AutoSplit> module can then be run manually to |
222 | extract the definitions into individual files F<auto/funcname.al>. |
223 | |
224 | B<AutoLoader> implements an AUTOLOAD subroutine. When an undefined |
225 | subroutine in is called in a client module of B<AutoLoader>, |
226 | B<AutoLoader>'s AUTOLOAD subroutine attempts to locate the subroutine in a |
227 | file with a name related to the location of the file from which the |
228 | client module was read. As an example, if F<POSIX.pm> is located in |
229 | F</usr/local/lib/perl5/POSIX.pm>, B<AutoLoader> will look for perl |
230 | subroutines B<POSIX> in F</usr/local/lib/perl5/auto/POSIX/*.al>, where |
231 | the C<.al> file has the same name as the subroutine, sans package. If |
232 | such a file exists, AUTOLOAD will read and evaluate it, |
233 | thus (presumably) defining the needed subroutine. AUTOLOAD will then |
234 | C<goto> the newly defined subroutine. |
235 | |
f610777f |
236 | Once this process completes for a given function, it is defined, so |
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237 | future calls to the subroutine will bypass the AUTOLOAD mechanism. |
238 | |
239 | =head2 Subroutine Stubs |
240 | |
241 | In order for object method lookup and/or prototype checking to operate |
242 | correctly even when methods have not yet been defined it is necessary to |
243 | "forward declare" each subroutine (as in C<sub NAME;>). See |
244 | L<perlsub/"SYNOPSIS">. Such forward declaration creates "subroutine |
245 | stubs", which are place holders with no code. |
246 | |
247 | The AutoSplit and B<AutoLoader> modules automate the creation of forward |
248 | declarations. The AutoSplit module creates an 'index' file containing |
249 | forward declarations of all the AutoSplit subroutines. When the |
250 | AutoLoader module is 'use'd it loads these declarations into its callers |
251 | package. |
252 | |
253 | Because of this mechanism it is important that B<AutoLoader> is always |
254 | C<use>d and not C<require>d. |
255 | |
256 | =head2 Using B<AutoLoader>'s AUTOLOAD Subroutine |
257 | |
258 | In order to use B<AutoLoader>'s AUTOLOAD subroutine you I<must> |
259 | explicitly import it: |
260 | |
261 | use AutoLoader 'AUTOLOAD'; |
262 | |
263 | =head2 Overriding B<AutoLoader>'s AUTOLOAD Subroutine |
264 | |
265 | Some modules, mainly extensions, provide their own AUTOLOAD subroutines. |
266 | They typically need to check for some special cases (such as constants) |
267 | and then fallback to B<AutoLoader>'s AUTOLOAD for the rest. |
268 | |
269 | Such modules should I<not> import B<AutoLoader>'s AUTOLOAD subroutine. |
270 | Instead, they should define their own AUTOLOAD subroutines along these |
271 | lines: |
272 | |
273 | use AutoLoader; |
fb73857a |
274 | use Carp; |
1be0b951 |
275 | |
276 | sub AUTOLOAD { |
7d4fbd98 |
277 | my $sub = $AUTOLOAD; |
278 | (my $constname = $sub) =~ s/.*:://; |
1be0b951 |
279 | my $val = constant($constname, @_ ? $_[0] : 0); |
280 | if ($! != 0) { |
265f5c4a |
281 | if ($! =~ /Invalid/ || $!{EINVAL}) { |
7d4fbd98 |
282 | $AutoLoader::AUTOLOAD = $sub; |
1be0b951 |
283 | goto &AutoLoader::AUTOLOAD; |
284 | } |
285 | else { |
286 | croak "Your vendor has not defined constant $constname"; |
287 | } |
288 | } |
7d4fbd98 |
289 | *$sub = sub { $val }; # same as: eval "sub $sub { $val }"; |
290 | goto &$sub; |
1be0b951 |
291 | } |
292 | |
293 | If any module's own AUTOLOAD subroutine has no need to fallback to the |
294 | AutoLoader's AUTOLOAD subroutine (because it doesn't have any AutoSplit |
295 | subroutines), then that module should not use B<AutoLoader> at all. |
296 | |
297 | =head2 Package Lexicals |
298 | |
299 | Package lexicals declared with C<my> in the main block of a package |
300 | using B<AutoLoader> will not be visible to auto-loaded subroutines, due to |
301 | the fact that the given scope ends at the C<__END__> marker. A module |
302 | using such variables as package globals will not work properly under the |
303 | B<AutoLoader>. |
304 | |
305 | The C<vars> pragma (see L<perlmod/"vars">) may be used in such |
306 | situations as an alternative to explicitly qualifying all globals with |
307 | the package namespace. Variables pre-declared with this pragma will be |
308 | visible to any autoloaded routines (but will not be invisible outside |
309 | the package, unfortunately). |
310 | |
cb0cff20 |
311 | =head2 Not Using AutoLoader |
312 | |
313 | You can stop using AutoLoader by simply |
314 | |
315 | no AutoLoader; |
316 | |
1be0b951 |
317 | =head2 B<AutoLoader> vs. B<SelfLoader> |
318 | |
319 | The B<AutoLoader> is similar in purpose to B<SelfLoader>: both delay the |
320 | loading of subroutines. |
321 | |
322 | B<SelfLoader> uses the C<__DATA__> marker rather than C<__END__>. |
323 | While this avoids the use of a hierarchy of disk files and the |
324 | associated open/close for each routine loaded, B<SelfLoader> suffers a |
325 | startup speed disadvantage in the one-time parsing of the lines after |
326 | C<__DATA__>, after which routines are cached. B<SelfLoader> can also |
327 | handle multiple packages in a file. |
328 | |
329 | B<AutoLoader> only reads code as it is requested, and in many cases |
f610777f |
330 | should be faster, but requires a mechanism like B<AutoSplit> be used to |
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331 | create the individual files. L<ExtUtils::MakeMaker> will invoke |
332 | B<AutoSplit> automatically if B<AutoLoader> is used in a module source |
333 | file. |
334 | |
335 | =head1 CAVEATS |
336 | |
337 | AutoLoaders prior to Perl 5.002 had a slightly different interface. Any |
338 | old modules which use B<AutoLoader> should be changed to the new calling |
339 | style. Typically this just means changing a require to a use, adding |
340 | the explicit C<'AUTOLOAD'> import if needed, and removing B<AutoLoader> |
341 | from C<@ISA>. |
342 | |
343 | On systems with restrictions on file name length, the file corresponding |
344 | to a subroutine may have a shorter name that the routine itself. This |
345 | can lead to conflicting file names. The I<AutoSplit> package warns of |
346 | these potential conflicts when used to split a module. |
347 | |
adaafad2 |
348 | AutoLoader may fail to find the autosplit files (or even find the wrong |
349 | ones) in cases where C<@INC> contains relative paths, B<and> the program |
350 | does C<chdir>. |
351 | |
1be0b951 |
352 | =head1 SEE ALSO |
353 | |
354 | L<SelfLoader> - an autoloader that doesn't use external files. |
355 | |
7a752413 |
356 | =head1 AUTHOR |
357 | |
358 | C<AutoLoader> is maintained by the perl5-porters. Please direct |
359 | any questions to the canonical mailing list. Anything that |
360 | is applicable to the CPAN release can be sent to its maintainer, |
361 | though. |
362 | |
363 | Author and Maintainer: The Perl5-Porters <perl5-porters@perl.org> |
364 | |
365 | Maintainer of the CPAN release: Steffen Mueller <smueller@cpan.org> |
366 | |
367 | =head1 COPYRIGHT AND LICENSE |
368 | |
369 | This package has been part of the perl core since the first release |
370 | of perl5. It has been released separately to CPAN so older installations |
371 | can benefit from bug fixes. |
372 | |
373 | This package has the same copyright and license as the perl core: |
374 | |
375 | Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, |
376 | 2000, 2001, 2002, 2003, 2004, 2005, 2006 by Larry Wall and others |
377 | |
378 | All rights reserved. |
379 | |
380 | This program is free software; you can redistribute it and/or modify |
381 | it under the terms of either: |
382 | |
383 | a) the GNU General Public License as published by the Free |
384 | Software Foundation; either version 1, or (at your option) any |
385 | later version, or |
386 | |
387 | b) the "Artistic License" which comes with this Kit. |
388 | |
389 | This program is distributed in the hope that it will be useful, |
390 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
391 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See either |
392 | the GNU General Public License or the Artistic License for more details. |
393 | |
394 | You should have received a copy of the Artistic License with this |
395 | Kit, in the file named "Artistic". If not, I'll be glad to provide one. |
396 | |
397 | You should also have received a copy of the GNU General Public License |
398 | along with this program in the file named "Copying". If not, write to the |
399 | Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
400 | 02111-1307, USA or visit their web page on the internet at |
401 | http://www.gnu.org/copyleft/gpl.html. |
402 | |
403 | For those of you that choose to use the GNU General Public License, |
404 | my interpretation of the GNU General Public License is that no Perl |
405 | script falls under the terms of the GPL unless you explicitly put |
406 | said script under the terms of the GPL yourself. Furthermore, any |
407 | object code linked with perl does not automatically fall under the |
408 | terms of the GPL, provided such object code only adds definitions |
409 | of subroutines and variables, and does not otherwise impair the |
410 | resulting interpreter from executing any standard Perl script. I |
411 | consider linking in C subroutines in this manner to be the moral |
412 | equivalent of defining subroutines in the Perl language itself. You |
413 | may sell such an object file as proprietary provided that you provide |
414 | or offer to provide the Perl source, as specified by the GNU General |
415 | Public License. (This is merely an alternate way of specifying input |
416 | to the program.) You may also sell a binary produced by the dumping of |
417 | a running Perl script that belongs to you, provided that you provide or |
418 | offer to provide the Perl source as specified by the GPL. (The |
419 | fact that a Perl interpreter and your code are in the same binary file |
420 | is, in this case, a form of mere aggregation.) This is my interpretation |
421 | of the GPL. If you still have concerns or difficulties understanding |
422 | my intent, feel free to contact me. Of course, the Artistic License |
423 | spells all this out for your protection, so you may prefer to use that. |
424 | |
1be0b951 |
425 | =cut |