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1 | package SelfLoader; |
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2 | use 5.008; |
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3 | use strict; |
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4 | our $VERSION = "1.15"; |
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5 | |
6 | # The following bit of eval-magic is necessary to make this work on |
7 | # perls < 5.009005. |
8 | use vars qw/$AttrList/; |
9 | BEGIN { |
10 | if ($] > 5.009004) { |
11 | eval <<'NEWERPERL'; |
12 | use 5.009005; # due to new regexp features |
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13 | # allow checking for valid ': attrlist' attachments |
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14 | # see also AutoSplit |
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15 | $AttrList = qr{ |
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16 | \s* : \s* |
17 | (?: |
18 | # one attribute |
19 | (?> # no backtrack |
20 | (?! \d) \w+ |
21 | (?<nested> \( (?: [^()]++ | (?&nested)++ )*+ \) ) ? |
22 | ) |
23 | (?: \s* : \s* | \s+ (?! :) ) |
24 | )* |
25 | }x; |
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26 | |
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27 | NEWERPERL |
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}) ) |
34 | our $nested; |
35 | $nested = qr{ \( (?: (?> [^()]+ ) | (??{ $nested }) )* \) }x; |
36 | our $one_attr = qr{ (?> (?! \d) \w+ (?:$nested)? ) (?:\s*\:\s*|\s+(?!\:)) }x; |
37 | $AttrList = qr{ \s* : \s* (?: $one_attr )* }x; |
38 | OLDERPERL |
39 | } |
40 | } |
41 | use Exporter; |
42 | our @ISA = qw(Exporter); |
43 | our @EXPORT = qw(AUTOLOAD); |
44 | sub Version {$VERSION} |
45 | sub DEBUG () { 0 } |
46 | |
47 | my %Cache; # private cache for all SelfLoader's client packages |
48 | |
cca8f13b |
49 | # in croak and carp, protect $@ from "require Carp;" RT #40216 |
50 | |
51 | sub croak { { local $@; require Carp; } goto &Carp::croak } |
52 | sub carp { { local $@; require Carp; } goto &Carp::carp } |
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53 | |
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54 | AUTOLOAD { |
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55 | our $AUTOLOAD; |
56 | print STDERR "SelfLoader::AUTOLOAD for $AUTOLOAD\n" if DEBUG; |
c7675058 |
57 | my $SL_code = $Cache{$AUTOLOAD}; |
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58 | my $save = $@; # evals in both AUTOLOAD and _load_stubs can corrupt $@ |
c7675058 |
59 | unless ($SL_code) { |
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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"}; |
c7675058 |
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; |
f8881bd9 |
68 | } |
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69 | print STDERR "SelfLoader::AUTOLOAD eval: $SL_code\n" if DEBUG; |
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70 | |
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71 | { |
72 | no strict; |
73 | eval $SL_code; |
74 | } |
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75 | if ($@) { |
76 | $@ =~ s/ at .*\n//; |
77 | croak $@; |
78 | } |
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79 | $@ = $save; |
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80 | defined(&$AUTOLOAD) || die "SelfLoader inconsistency error"; |
81 | delete $Cache{$AUTOLOAD}; |
82 | goto &$AUTOLOAD |
83 | } |
84 | |
85 | sub load_stubs { shift->_load_stubs((caller)[0]) } |
86 | |
87 | sub _load_stubs { |
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88 | # $endlines is used by Devel::SelfStubber to capture lines after __END__ |
89 | my($self, $callpack, $endlines) = @_; |
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90 | no strict "refs"; |
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91 | my $fh = \*{"${callpack}::DATA"}; |
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92 | use strict; |
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93 | my $currpack = $callpack; |
94 | my($line,$name,@lines, @stubs, $protoype); |
95 | |
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96 | print STDERR "SelfLoader::load_stubs($callpack)\n" if DEBUG; |
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97 | croak("$callpack doesn't contain an __DATA__ token") |
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98 | unless defined fileno($fh); |
add1a1a3 |
99 | # Protect: fork() shares the file pointer between the parent and the kid |
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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 |
105 | } |
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106 | $Cache{"${currpack}::<DATA"} = 1; # indicate package is cached |
107 | |
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108 | local($/) = "\n"; |
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109 | while(defined($line = <$fh>) and $line !~ m/^__END__/) { |
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110 | if ($line =~ m/^\s*sub\s+([\w:]+)\s*((?:\([\\\$\@\%\&\*\;]*\))?(?:$AttrList)?)/) { |
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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,$line); |
143 | } |
144 | } |
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145 | if (defined($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 | } |
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155 | push(@stubs, $self->_add_to_cache($name, $currpack, \@lines, $protoype)); |
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156 | no strict; |
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157 | eval join('', @stubs) if @stubs; |
158 | } |
159 | |
160 | |
161 | sub _add_to_cache { |
162 | my($self,$fullname,$pack,$lines, $protoype) = @_; |
163 | return () unless $fullname; |
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164 | carp("Redefining sub $fullname") |
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165 | if exists $Cache{$fullname}; |
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166 | $Cache{$fullname} = join('', "package $pack; ",@$lines); |
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167 | print STDERR "SelfLoader cached $fullname: $Cache{$fullname}" if DEBUG; |
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168 | # return stub to be eval'd |
169 | defined($protoype) ? "sub $fullname $protoype;" : "sub $fullname;" |
170 | } |
171 | |
172 | sub _package_defined {} |
173 | |
174 | 1; |
175 | __END__ |
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176 | |
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177 | =head1 NAME |
178 | |
179 | SelfLoader - load functions only on demand |
180 | |
181 | =head1 SYNOPSIS |
182 | |
183 | package FOOBAR; |
184 | use SelfLoader; |
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185 | |
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186 | ... (initializing code) |
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187 | |
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188 | __DATA__ |
189 | sub {.... |
190 | |
191 | |
192 | =head1 DESCRIPTION |
193 | |
194 | This module tells its users that functions in the FOOBAR package are to be |
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195 | autoloaded from after the C<__DATA__> token. See also |
196 | L<perlsub/"Autoloading">. |
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197 | |
198 | =head2 The __DATA__ token |
199 | |
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200 | The C<__DATA__> token tells the perl compiler that the perl code |
201 | for compilation is finished. Everything after the C<__DATA__> token |
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202 | is available for reading via the filehandle FOOBAR::DATA, |
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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 |
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206 | automatically retrievable, whereas data after C<__DATA__> is. |
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207 | The C<__DATA__> token is not recognized in versions of perl prior to |
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208 | 5.001m. |
209 | |
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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 |
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212 | package that is encountered by the compiler is the one accessible |
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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' |
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218 | program, since the compiler encounters the 'require'd file later. |
219 | |
220 | =head2 SelfLoader autoloading |
221 | |
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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 |
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225 | that can be loaded in later - usually because they may never |
226 | be called. |
227 | |
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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 |
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230 | when it is called. The costs are the one-time parsing of the |
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231 | data after C<__DATA__>, and a load delay for the _first_ |
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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. |
235 | |
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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 |
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240 | filehandle open on the line after that token. |
241 | |
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242 | The B<SelfLoader> exports the C<AUTOLOAD> subroutine to the |
243 | package using the B<SelfLoader>, and this loads the called |
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244 | subroutine when it is first called. |
245 | |
246 | There is no advantage to putting subroutines which will _always_ |
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247 | be called after the C<__DATA__> token. |
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248 | |
249 | =head2 Autoloading and package lexicals |
250 | |
251 | A 'my $pack_lexical' statement makes the variable $pack_lexical |
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252 | local _only_ to the file up to the C<__DATA__> token. Subroutines |
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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. |
256 | |
257 | So specifically, autoloaded functions cannot see package |
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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>. |
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262 | |
263 | =head2 SelfLoader and AutoLoader |
264 | |
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265 | The B<SelfLoader> can replace the AutoLoader - just change 'use AutoLoader' |
266 | to 'use SelfLoader' (though note that the B<SelfLoader> exports |
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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), |
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269 | and the C<__END__> token to C<__DATA__>. You will need perl version 5.001m |
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270 | or later to use this (version 5.001 with all patches up to patch m). |
271 | |
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272 | There is no need to inherit from the B<SelfLoader>. |
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273 | |
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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. |
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276 | There is a maintenance gain in not needing to run AutoSplit on the module |
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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 |
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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 |
281 | documentation. |
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282 | |
283 | =head2 __DATA__, __END__, and the FOOBAR::DATA filehandle. |
284 | |
285 | This section is only relevant if you want to use |
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286 | the C<FOOBAR::DATA> together with the B<SelfLoader>. |
287 | |
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. |
296 | |
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 |
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300 | that filehandle (and ONLY if you want to), you should either |
301 | |
302 | 1. Put all your subroutine declarations immediately after |
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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> |
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306 | reads first by calling 'SelfLoader-E<gt>load_stubs();', or by using a |
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307 | function which is selfloaded; |
308 | |
309 | or |
310 | |
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311 | 2. You should read the C<FOOBAR::DATA> filehandle first, leaving |
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312 | the handle open and positioned at the first line of subroutine |
313 | declarations. |
314 | |
315 | You could conceivably do both. |
316 | |
317 | =head2 Classes and inherited methods. |
318 | |
319 | For modules which are not classes, this section is not relevant. |
320 | This section is only relevant if you have methods which could |
321 | be inherited. |
322 | |
323 | A subroutine stub (or forward declaration) looks like |
324 | |
325 | sub stub; |
326 | |
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. |
330 | |
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 |
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334 | adding the statement 'SelfLoader-E<gt>load_stubs();' to the module to do |
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335 | this. |
336 | |
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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> |
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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. |
343 | |
344 | =head1 Multiple packages and fully qualified subroutine names |
345 | |
346 | Subroutines in multiple packages within the same file are supported - but you |
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347 | should note that this requires exporting the C<SelfLoader::AUTOLOAD> to |
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348 | every package which requires it. This is done automatically by the |
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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 |
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351 | a 'use SelfLoader' statement in each package. |
352 | |
353 | Fully qualified subroutine names are also supported. For example, |
354 | |
355 | __DATA__ |
356 | sub foo::bar {23} |
357 | package baz; |
358 | sub dob {32} |
359 | |
463e8aa9 |
360 | will all be loaded correctly by the B<SelfLoader>, and the B<SelfLoader> |
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361 | will ensure that the packages 'foo' and 'baz' correctly have the |
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362 | B<SelfLoader> C<AUTOLOAD> method when the data after C<__DATA__> is first |
363 | parsed. |
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364 | |
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365 | =head1 AUTHOR |
366 | |
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, |
370 | though. |
371 | |
372 | Author and Maintainer: The Perl5-Porters <perl5-porters@perl.org> |
373 | |
374 | Maintainer of the CPAN release: Steffen Mueller <smueller@cpan.org> |
375 | |
376 | =head1 COPYRIGHT AND LICENSE |
377 | |
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. |
381 | |
382 | This package has the same copyright and license as the perl core: |
383 | |
384 | Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, |
385 | 2000, 2001, 2002, 2003, 2004, 2005, 2006 by Larry Wall and others |
386 | |
387 | All rights reserved. |
388 | |
389 | This program is free software; you can redistribute it and/or modify |
390 | it under the terms of either: |
391 | |
392 | a) the GNU General Public License as published by the Free |
393 | Software Foundation; either version 1, or (at your option) any |
394 | later version, or |
395 | |
396 | b) the "Artistic License" which comes with this Kit. |
397 | |
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. |
402 | |
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. |
405 | |
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. |
411 | |
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. |
433 | |
f8881bd9 |
434 | =cut |