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a0d0e21e |
1 | package DynaLoader; |
2 | |
8e07c86e |
3 | # And Gandalf said: 'Many folk like to know beforehand what is to |
4 | # be set on the table; but those who have laboured to prepare the |
5 | # feast like to keep their secret; for wonder makes the words of |
6 | # praise louder.' |
7 | |
8 | # (Quote from Tolkien sugested by Anno Siegel.) |
9 | # |
10 | # See pod text at end of file for documentation. |
11 | # See also ext/DynaLoader/README in source tree for other information. |
12 | # |
13 | # Tim.Bunce@ig.co.uk, August 1994 |
14 | |
15 | require Carp; |
16 | require Config; |
17 | require AutoLoader; |
18 | |
19 | @ISA=qw(AutoLoader); |
20 | |
21 | |
22 | sub import { } # override import inherited from AutoLoader |
23 | |
24 | # enable debug/trace messages from DynaLoader perl code |
25 | $dl_debug = $ENV{PERL_DL_DEBUG} || 0 unless defined $dl_debug; |
26 | |
27 | ($dl_dlext, $dlsrc, $osname) |
28 | = @Config::Config{'dlext', 'dlsrc', 'osname'}; |
29 | |
30 | # Some systems need special handling to expand file specifications |
31 | # (VMS support by Charles Bailey <bailey@HMIVAX.HUMGEN.UPENN.EDU>) |
32 | # See dl_expandspec() for more details. Should be harmless but |
33 | # inefficient to define on systems that don't need it. |
34 | $do_expand = ($osname eq 'VMS'); |
35 | |
36 | @dl_require_symbols = (); # names of symbols we need |
37 | @dl_resolve_using = (); # names of files to link with |
38 | @dl_library_path = (); # path to look for files |
39 | |
40 | # This is a fix to support DLD's unfortunate desire to relink -lc |
41 | @dl_resolve_using = dl_findfile('-lc') if $dlsrc eq "dl_dld.xs"; |
42 | |
43 | # Initialise @dl_library_path with the 'standard' library path |
44 | # for this platform as determined by Configure |
45 | push(@dl_library_path, split(' ',$Config::Config{'libpth'})); |
46 | |
47 | # Add to @dl_library_path any extra directories we can gather from |
48 | # environment variables. So far LD_LIBRARY_PATH is the only known |
49 | # variable used for this purpose. Others may be added later. |
50 | push(@dl_library_path, split(/:/, $ENV{LD_LIBRARY_PATH})) |
51 | if $ENV{LD_LIBRARY_PATH}; |
52 | |
53 | |
54 | # No prizes for guessing why we don't say 'bootstrap DynaLoader;' here. |
55 | boot_DynaLoader() if defined(&boot_DynaLoader); |
56 | |
57 | |
58 | if ($dl_debug) { |
59 | print STDERR "DynaLoader.pm loaded (@INC, @dl_library_path)\n"; |
60 | print STDERR "DynaLoader not linked into this perl\n" |
61 | unless defined(&boot_DynaLoader); |
62 | } |
63 | |
64 | 1; # End of main code |
65 | |
66 | |
67 | # The bootstrap function cannot be autoloaded (without complications) |
68 | # so we define it here: |
69 | |
70 | sub bootstrap { |
71 | # use local vars to enable $module.bs script to edit values |
72 | local(@args) = @_; |
73 | local($module) = $args[0]; |
74 | local(@dirs, $file); |
75 | |
4633a7c4 |
76 | Carp::confess("Usage: DynaLoader::bootstrap(module)") unless $module; |
8e07c86e |
77 | |
78 | # A common error on platforms which don't support dynamic loading. |
79 | # Since it's fatal and potentially confusing we give a detailed message. |
80 | Carp::croak("Can't load module $module, dynamic loading not available in this perl.\n". |
81 | " (You may need to build a new perl executable which either supports\n". |
82 | " dynamic loading or has the $module module statically linked into it.)\n") |
83 | unless defined(&dl_load_file); |
84 | |
85 | my @modparts = split(/::/,$module); |
86 | my $modfname = $modparts[-1]; |
87 | |
88 | # Some systems have restrictions on files names for DLL's etc. |
89 | # mod2fname returns appropriate file base name (typically truncated) |
90 | # It may also edit @modparts if required. |
91 | $modfname = &mod2fname(\@modparts) if defined &mod2fname; |
92 | |
93 | my $modpname = join('/',@modparts); |
94 | |
95 | print STDERR "DynaLoader::bootstrap for $module ", |
96 | "(auto/$modpname/$modfname.$dl_dlext)\n" if $dl_debug; |
97 | |
98 | foreach (@INC) { |
99 | my $dir = "$_/auto/$modpname"; |
100 | next unless -d $dir; # skip over uninteresting directories |
101 | |
102 | # check for common cases to avoid autoload of dl_findfile |
103 | last if ($file=_check_file("$dir/$modfname.$dl_dlext")); |
104 | |
105 | # no luck here, save dir for possible later dl_findfile search |
106 | push(@dirs, "-L$dir"); |
107 | } |
108 | # last resort, let dl_findfile have a go in all known locations |
109 | $file = dl_findfile(@dirs, map("-L$_",@INC), $modfname) unless $file; |
110 | |
4633a7c4 |
111 | Carp::croak("Can't find loadable object for module $module in \@INC (@INC)") |
8e07c86e |
112 | unless $file; |
113 | |
114 | my $bootname = "boot_$module"; |
115 | $bootname =~ s/\W/_/g; |
116 | @dl_require_symbols = ($bootname); |
117 | |
118 | # Execute optional '.bootstrap' perl script for this module. |
119 | # The .bs file can be used to configure @dl_resolve_using etc to |
120 | # match the needs of the individual module on this architecture. |
121 | my $bs = $file; |
122 | $bs =~ s/(\.\w+)?$/\.bs/; # look for .bs 'beside' the library |
123 | if (-s $bs) { # only read file if it's not empty |
124 | print STDERR "BS: $bs ($osname, $dlsrc)\n" if $dl_debug; |
125 | eval { do $bs; }; |
126 | warn "$bs: $@\n" if $@; |
127 | } |
128 | |
129 | # Many dynamic extension loading problems will appear to come from |
130 | # this section of code: XYZ failed at line 123 of DynaLoader.pm. |
131 | # Often these errors are actually occurring in the initialisation |
132 | # C code of the extension XS file. Perl reports the error as being |
133 | # in this perl code simply because this was the last perl code |
134 | # it executed. |
135 | |
136 | my $libref = dl_load_file($file) or |
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137 | Carp::croak("Can't load '$file' for module $module: ".dl_error()."\n"); |
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138 | |
139 | my @unresolved = dl_undef_symbols(); |
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140 | Carp::carp("Undefined symbols present after loading $file: @unresolved\n") |
8e07c86e |
141 | if @unresolved; |
142 | |
143 | my $boot_symbol_ref = dl_find_symbol($libref, $bootname) or |
4633a7c4 |
144 | Carp::croak("Can't find '$bootname' symbol in $file\n"); |
8e07c86e |
145 | |
146 | my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file); |
147 | |
148 | # See comment block above |
149 | &$xs(@args); |
150 | } |
151 | |
152 | |
153 | sub _check_file { # private utility to handle dl_expandspec vs -f tests |
154 | my($file) = @_; |
155 | return $file if (!$do_expand && -f $file); # the common case |
156 | return $file if ( $do_expand && ($file=dl_expandspec($file))); |
157 | return undef; |
158 | } |
159 | |
160 | |
161 | # Let autosplit and the autoloader deal with these functions: |
162 | __END__ |
163 | |
164 | |
165 | sub dl_findfile { |
166 | # Read ext/DynaLoader/DynaLoader.doc for detailed information. |
167 | # This function does not automatically consider the architecture |
168 | # or the perl library auto directories. |
169 | my (@args) = @_; |
170 | my (@dirs, $dir); # which directories to search |
171 | my (@found); # full paths to real files we have found |
172 | my $vms = ($osname eq 'VMS'); |
173 | my $dl_so = $Config::Config{'so'}; # suffix for shared libraries |
174 | |
175 | print STDERR "dl_findfile(@args)\n" if $dl_debug; |
176 | |
177 | # accumulate directories but process files as they appear |
178 | arg: foreach(@args) { |
179 | # Special fast case: full filepath requires no search |
180 | if (m:/: && -f $_ && !$do_expand) { |
181 | push(@found,$_); |
182 | last arg unless wantarray; |
183 | next; |
184 | } |
185 | |
186 | # Deal with directories first: |
187 | # Using a -L prefix is the preferred option (faster and more robust) |
188 | if (m:^-L:) { s/^-L//; push(@dirs, $_); next; } |
189 | |
190 | # Otherwise we try to try to spot directories by a heuristic |
191 | # (this is a more complicated issue than it first appears) |
192 | if (m:/: && -d $_) { push(@dirs, $_); next; } |
193 | |
194 | # VMS: we may be using native VMS directry syntax instead of |
195 | # Unix emulation, so check this as well |
196 | if ($vms && /[:>\]]/ && -d $_) { push(@dirs, $_); next; } |
197 | |
198 | # Only files should get this far... |
199 | my(@names, $name); # what filenames to look for |
200 | if (m:-l: ) { # convert -lname to appropriate library name |
201 | s/-l//; |
202 | push(@names,"lib$_.$dl_so"); |
203 | push(@names,"lib$_.a"); |
204 | } else { # Umm, a bare name. Try various alternatives: |
205 | # these should be ordered with the most likely first |
206 | push(@names,"$_.$dl_so") unless m/\.$dl_so$/o; |
207 | push(@names,"lib$_.$dl_so") unless m:/:; |
208 | push(@names,"$_.o") unless m/\.(o|$dl_so)$/o; |
209 | push(@names,"$_.a") if !m/\.a$/ and $dlsrc eq "dl_dld.xs"; |
210 | push(@names, $_); |
211 | } |
212 | foreach $dir (@dirs, @dl_library_path) { |
213 | next unless -d $dir; |
214 | foreach $name (@names) { |
215 | my($file) = "$dir/$name"; |
216 | print STDERR " checking in $dir for $name\n" if $dl_debug; |
217 | $file = _check_file($file); |
218 | if ($file) { |
219 | push(@found, $file); |
220 | next arg; # no need to look any further |
221 | } |
222 | } |
223 | } |
224 | } |
225 | if ($dl_debug) { |
226 | foreach(@dirs) { |
227 | print STDERR " dl_findfile ignored non-existent directory: $_\n" unless -d $_; |
228 | } |
229 | print STDERR "dl_findfile found: @found\n"; |
230 | } |
231 | return $found[0] unless wantarray; |
232 | @found; |
233 | } |
234 | |
235 | |
236 | sub dl_expandspec { |
237 | my($spec) = @_; |
238 | # Optional function invoked if DynaLoader.pm sets $do_expand. |
239 | # Most systems do not require or use this function. |
240 | # Some systems may implement it in the dl_*.xs file in which case |
241 | # this autoload version will not be called but is harmless. |
242 | |
243 | # This function is designed to deal with systems which treat some |
244 | # 'filenames' in a special way. For example VMS 'Logical Names' |
245 | # (something like unix environment variables - but different). |
246 | # This function should recognise such names and expand them into |
247 | # full file paths. |
248 | # Must return undef if $spec is invalid or file does not exist. |
249 | |
250 | my $file = $spec; # default output to input |
251 | |
252 | if ($osname eq 'VMS') { # dl_expandspec should be defined in dl_vms.xs |
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253 | Carp::croak("dl_expandspec: should be defined in XS file!\n"); |
8e07c86e |
254 | } else { |
255 | return undef unless -f $file; |
256 | } |
257 | print STDERR "dl_expandspec($spec) => $file\n" if $dl_debug; |
258 | $file; |
259 | } |
260 | |
261 | |
3b35bae3 |
262 | =head1 NAME |
263 | |
264 | DynaLoader - Dynamically load C libraries into Perl code |
265 | |
266 | dl_error(), dl_findfile(), dl_expandspec(), dl_load_file(), dl_find_symbol(), dl_undef_symbols(), dl_install_xsub(), boostrap() - routines used by DynaLoader modules |
267 | |
268 | =head1 SYNOPSIS |
269 | |
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270 | package YourPackage; |
3b35bae3 |
271 | require DynaLoader; |
c2960299 |
272 | @ISA = qw(... DynaLoader ...); |
8e07c86e |
273 | bootstrap YourPackage; |
3b35bae3 |
274 | |
275 | |
276 | =head1 DESCRIPTION |
277 | |
c2960299 |
278 | This document defines a standard generic interface to the dynamic |
3b35bae3 |
279 | linking mechanisms available on many platforms. Its primary purpose is |
280 | to implement automatic dynamic loading of Perl modules. |
281 | |
c2960299 |
282 | This document serves as both a specification for anyone wishing to |
283 | implement the DynaLoader for a new platform and as a guide for |
284 | anyone wishing to use the DynaLoader directly in an application. |
285 | |
3b35bae3 |
286 | The DynaLoader is designed to be a very simple high-level |
287 | interface that is sufficiently general to cover the requirements |
288 | of SunOS, HP-UX, NeXT, Linux, VMS and other platforms. |
289 | |
c2960299 |
290 | It is also hoped that the interface will cover the needs of OS/2, NT |
291 | etc and also allow pseudo-dynamic linking (using C<ld -A> at runtime). |
3b35bae3 |
292 | |
293 | It must be stressed that the DynaLoader, by itself, is practically |
294 | useless for accessing non-Perl libraries because it provides almost no |
295 | Perl-to-C 'glue'. There is, for example, no mechanism for calling a C |
296 | library function or supplying arguments. It is anticipated that any |
297 | glue that may be developed in the future will be implemented in a |
298 | separate dynamically loaded module. |
299 | |
300 | DynaLoader Interface Summary |
301 | |
302 | @dl_library_path |
303 | @dl_resolve_using |
304 | @dl_require_symbols |
305 | $dl_debug |
306 | Implemented in: |
307 | bootstrap($modulename) Perl |
308 | @filepaths = dl_findfile(@names) Perl |
309 | |
310 | $libref = dl_load_file($filename) C |
311 | $symref = dl_find_symbol($libref, $symbol) C |
312 | @symbols = dl_undef_symbols() C |
313 | dl_install_xsub($name, $symref [, $filename]) C |
314 | $message = dl_error C |
315 | |
316 | =over 4 |
317 | |
318 | =item @dl_library_path |
319 | |
320 | The standard/default list of directories in which dl_findfile() will |
321 | search for libraries etc. Directories are searched in order: |
322 | $dl_library_path[0], [1], ... etc |
323 | |
324 | @dl_library_path is initialised to hold the list of 'normal' directories |
325 | (F</usr/lib>, etc) determined by B<Configure> (C<$Config{'libpth'}>). This should |
326 | ensure portability across a wide range of platforms. |
327 | |
328 | @dl_library_path should also be initialised with any other directories |
329 | that can be determined from the environment at runtime (such as |
330 | LD_LIBRARY_PATH for SunOS). |
331 | |
332 | After initialisation @dl_library_path can be manipulated by an |
333 | application using push and unshift before calling dl_findfile(). |
334 | Unshift can be used to add directories to the front of the search order |
335 | either to save search time or to override libraries with the same name |
336 | in the 'normal' directories. |
337 | |
338 | The load function that dl_load_file() calls may require an absolute |
339 | pathname. The dl_findfile() function and @dl_library_path can be |
340 | used to search for and return the absolute pathname for the |
341 | library/object that you wish to load. |
342 | |
343 | =item @dl_resolve_using |
344 | |
345 | A list of additional libraries or other shared objects which can be |
346 | used to resolve any undefined symbols that might be generated by a |
347 | later call to load_file(). |
348 | |
349 | This is only required on some platforms which do not handle dependent |
350 | libraries automatically. For example the Socket Perl extension library |
351 | (F<auto/Socket/Socket.so>) contains references to many socket functions |
352 | which need to be resolved when it's loaded. Most platforms will |
353 | automatically know where to find the 'dependent' library (e.g., |
354 | F</usr/lib/libsocket.so>). A few platforms need to to be told the location |
355 | of the dependent library explicitly. Use @dl_resolve_using for this. |
356 | |
357 | Example usage: |
358 | |
359 | @dl_resolve_using = dl_findfile('-lsocket'); |
360 | |
361 | =item @dl_require_symbols |
362 | |
363 | A list of one or more symbol names that are in the library/object file |
364 | to be dynamically loaded. This is only required on some platforms. |
365 | |
366 | =item dl_error() |
367 | |
368 | Syntax: |
369 | |
370 | $message = dl_error(); |
371 | |
372 | Error message text from the last failed DynaLoader function. Note |
373 | that, similar to errno in unix, a successful function call does not |
374 | reset this message. |
375 | |
376 | Implementations should detect the error as soon as it occurs in any of |
377 | the other functions and save the corresponding message for later |
378 | retrieval. This will avoid problems on some platforms (such as SunOS) |
379 | where the error message is very temporary (e.g., dlerror()). |
380 | |
381 | =item $dl_debug |
382 | |
383 | Internal debugging messages are enabled when $dl_debug is set true. |
384 | Currently setting $dl_debug only affects the Perl side of the |
385 | DynaLoader. These messages should help an application developer to |
386 | resolve any DynaLoader usage problems. |
387 | |
388 | $dl_debug is set to C<$ENV{'PERL_DL_DEBUG'}> if defined. |
389 | |
390 | For the DynaLoader developer/porter there is a similar debugging |
391 | variable added to the C code (see dlutils.c) and enabled if Perl was |
392 | built with the B<-DDEBUGGING> flag. This can also be set via the |
393 | PERL_DL_DEBUG environment variable. Set to 1 for minimal information or |
394 | higher for more. |
395 | |
396 | =item dl_findfile() |
397 | |
398 | Syntax: |
399 | |
400 | @filepaths = dl_findfile(@names) |
401 | |
402 | Determine the full paths (including file suffix) of one or more |
403 | loadable files given their generic names and optionally one or more |
404 | directories. Searches directories in @dl_library_path by default and |
405 | returns an empty list if no files were found. |
406 | |
407 | Names can be specified in a variety of platform independent forms. Any |
408 | names in the form B<-lname> are converted into F<libname.*>, where F<.*> is |
409 | an appropriate suffix for the platform. |
410 | |
411 | If a name does not already have a suitable prefix and/or suffix then |
412 | the corresponding file will be searched for by trying combinations of |
413 | prefix and suffix appropriate to the platform: "$name.o", "lib$name.*" |
414 | and "$name". |
415 | |
416 | If any directories are included in @names they are searched before |
c2960299 |
417 | @dl_library_path. Directories may be specified as B<-Ldir>. Any other |
418 | names are treated as filenames to be searched for. |
3b35bae3 |
419 | |
420 | Using arguments of the form C<-Ldir> and C<-lname> is recommended. |
421 | |
422 | Example: |
423 | |
424 | @dl_resolve_using = dl_findfile(qw(-L/usr/5lib -lposix)); |
425 | |
426 | |
427 | =item dl_expandspec() |
428 | |
429 | Syntax: |
430 | |
431 | $filepath = dl_expandspec($spec) |
432 | |
433 | Some unusual systems, such as VMS, require special filename handling in |
434 | order to deal with symbolic names for files (i.e., VMS's Logical Names). |
435 | |
436 | To support these systems a dl_expandspec() function can be implemented |
437 | either in the F<dl_*.xs> file or code can be added to the autoloadable |
c2960299 |
438 | dl_expandspec() function in F<DynaLoader.pm>. See F<DynaLoader.pm> for |
439 | more information. |
3b35bae3 |
440 | |
441 | =item dl_load_file() |
442 | |
443 | Syntax: |
444 | |
445 | $libref = dl_load_file($filename) |
446 | |
447 | Dynamically load $filename, which must be the path to a shared object |
448 | or library. An opaque 'library reference' is returned as a handle for |
449 | the loaded object. Returns undef on error. |
450 | |
451 | (On systems that provide a handle for the loaded object such as SunOS |
452 | and HPUX, $libref will be that handle. On other systems $libref will |
453 | typically be $filename or a pointer to a buffer containing $filename. |
454 | The application should not examine or alter $libref in any way.) |
455 | |
456 | This is function that does the real work. It should use the current |
457 | values of @dl_require_symbols and @dl_resolve_using if required. |
458 | |
459 | SunOS: dlopen($filename) |
460 | HP-UX: shl_load($filename) |
461 | Linux: dld_create_reference(@dl_require_symbols); dld_link($filename) |
462 | NeXT: rld_load($filename, @dl_resolve_using) |
463 | VMS: lib$find_image_symbol($filename,$dl_require_symbols[0]) |
464 | |
465 | |
466 | =item dl_find_symbol() |
467 | |
468 | Syntax: |
469 | |
470 | $symref = dl_find_symbol($libref, $symbol) |
471 | |
472 | Return the address of the symbol $symbol or C<undef> if not found. If the |
473 | target system has separate functions to search for symbols of different |
474 | types then dl_find_symbol() should search for function symbols first and |
475 | then other types. |
476 | |
477 | The exact manner in which the address is returned in $symref is not |
478 | currently defined. The only initial requirement is that $symref can |
479 | be passed to, and understood by, dl_install_xsub(). |
480 | |
481 | SunOS: dlsym($libref, $symbol) |
482 | HP-UX: shl_findsym($libref, $symbol) |
483 | Linux: dld_get_func($symbol) and/or dld_get_symbol($symbol) |
484 | NeXT: rld_lookup("_$symbol") |
485 | VMS: lib$find_image_symbol($libref,$symbol) |
486 | |
487 | |
488 | =item dl_undef_symbols() |
489 | |
490 | Example |
491 | |
492 | @symbols = dl_undef_symbols() |
493 | |
494 | Return a list of symbol names which remain undefined after load_file(). |
495 | Returns C<()> if not known. Don't worry if your platform does not provide |
c2960299 |
496 | a mechanism for this. Most do not need it and hence do not provide it, |
497 | they just return an empty list. |
3b35bae3 |
498 | |
499 | |
500 | =item dl_install_xsub() |
501 | |
502 | Syntax: |
503 | |
504 | dl_install_xsub($perl_name, $symref [, $filename]) |
505 | |
506 | Create a new Perl external subroutine named $perl_name using $symref as |
507 | a pointer to the function which implements the routine. This is simply |
508 | a direct call to newXSUB(). Returns a reference to the installed |
509 | function. |
510 | |
511 | The $filename parameter is used by Perl to identify the source file for |
512 | the function if required by die(), caller() or the debugger. If |
513 | $filename is not defined then "DynaLoader" will be used. |
514 | |
515 | |
516 | =item boostrap() |
517 | |
518 | Syntax: |
519 | |
520 | bootstrap($module) |
521 | |
522 | This is the normal entry point for automatic dynamic loading in Perl. |
523 | |
524 | It performs the following actions: |
525 | |
526 | =over 8 |
527 | |
528 | =item * |
529 | |
530 | locates an auto/$module directory by searching @INC |
531 | |
532 | =item * |
533 | |
534 | uses dl_findfile() to determine the filename to load |
535 | |
536 | =item * |
537 | |
538 | sets @dl_require_symbols to C<("boot_$module")> |
539 | |
540 | =item * |
541 | |
542 | executes an F<auto/$module/$module.bs> file if it exists |
543 | (typically used to add to @dl_resolve_using any files which |
544 | are required to load the module on the current platform) |
545 | |
546 | =item * |
547 | |
548 | calls dl_load_file() to load the file |
549 | |
550 | =item * |
551 | |
552 | calls dl_undef_symbols() and warns if any symbols are undefined |
553 | |
554 | =item * |
555 | |
556 | calls dl_find_symbol() for "boot_$module" |
557 | |
558 | =item * |
559 | |
560 | calls dl_install_xsub() to install it as "${module}::bootstrap" |
561 | |
562 | =item * |
563 | |
8e07c86e |
564 | calls &{"${module}::bootstrap"} to bootstrap the module (actually |
565 | it uses the function reference returned by dl_install_xsub for speed) |
3b35bae3 |
566 | |
567 | =back |
568 | |
569 | =back |
570 | |
571 | |
572 | =head1 AUTHOR |
573 | |
c2960299 |
574 | Tim Bunce, 11 August 1994. |
575 | |
3b35bae3 |
576 | This interface is based on the work and comments of (in no particular |
577 | order): Larry Wall, Robert Sanders, Dean Roehrich, Jeff Okamoto, Anno |
c2960299 |
578 | Siegel, Thomas Neumann, Paul Marquess, Charles Bailey, myself and others. |
3b35bae3 |
579 | |
580 | Larry Wall designed the elegant inherited bootstrap mechanism and |
581 | implemented the first Perl 5 dynamic loader using it. |
582 | |
3b35bae3 |
583 | =cut |