Some escapes were mentioned twice, although they're not qr//-specific
[p5sagit/p5-mst-13.2.git] / Porting / pumpkin.pod
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aa689395 1=head1 NAME
2
e25f343d 3Pumpkin - Notes on handling the Perl Patch Pumpkin And Porting Perl
aa689395 4
5=head1 SYNOPSIS
6
7There is no simple synopsis, yet.
8
9=head1 DESCRIPTION
10
98dddfbd 11This document attempts to begin to describe some of the considerations
12involved in patching, porting, and maintaining perl.
aa689395 13
14This document is still under construction, and still subject to
15significant changes. Still, I hope parts of it will be useful,
16so I'm releasing it even though it's not done.
17
18For the most part, it's a collection of anecdotal information that
19already assumes some familiarity with the Perl sources. I really need
20an introductory section that describes the organization of the sources
21and all the various auxiliary files that are part of the distribution.
22
23=head1 Where Do I Get Perl Sources and Related Material?
24
25The Comprehensive Perl Archive Network (or CPAN) is the place to go.
26There are many mirrors, but the easiest thing to use is probably
a93751fa 27http://www.cpan.org/README.html , which automatically points you to a
aa689395 28mirror site "close" to you.
29
30=head2 Perl5-porters mailing list
31
32The mailing list perl5-porters@perl.org
33is the main group working with the development of perl. If you're
34interested in all the latest developments, you should definitely
35subscribe. The list is high volume, but generally has a
36fairly low noise level.
37
38Subscribe by sending the message (in the body of your letter)
39
40 subscribe perl5-porters
41
42to perl5-porters-request@perl.org .
43
fb73857a 44Archives of the list are held at:
45
f38c94f4 46 http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/
fb73857a 47
aa689395 48=head1 How are Perl Releases Numbered?
49
f5a32c7f 50Beginning with v5.6.0, even versions will stand for maintenance releases
51and odd versions for development releases, i.e., v5.6.x for maintenance
52releases, and v5.7.x for development releases. Before v5.6.0, subversions
53_01 through _49 were reserved for bug-fix maintenance releases, and
54subversions _50 through _99 for unstable development versions.
7b5757d1 55
f5a32c7f 56For example, in v5.6.1, the revision number is 5, the version is 6,
57and 1 is the subversion.
aa689395 58
f5a32c7f 59For compatibility with the older numbering scheme the composite floating
60point version number continues to be available as the magic variable $],
76ba0908 61and amounts to C<$revision + $version/1000 + $subversion/100000>. This
f5a32c7f 62can still be used in comparisons.
aa689395 63
f5a32c7f 64 print "You've got an old perl\n" if $] < 5.005_03;
aa689395 65
f5a32c7f 66In addition, the version is also available as a string in $^V.
aa689395 67
f5a32c7f 68 print "You've got a new perl\n" if $^V and $^V ge v5.6.0;
7b5757d1 69
f5a32c7f 70You can also require particular version (or later) with:
aa689395 71
f5a32c7f 72 use 5.006;
aa689395 73
f5a32c7f 74or using the new syntax available only from v5.6 onward:
aa689395 75
f5a32c7f 76 use v5.6.0;
aa689395 77
f5a32c7f 78At some point in the future, we may need to decide what to call the
79next big revision. In the .package file used by metaconfig to
80generate Configure, there are two variables that might be relevant:
81$baserev=5 and $package=perl5.
aa689395 82
f5a32c7f 83Perl releases produced by the members of perl5-porters are usually
e04b929a 84available on CPAN in the F<src/5.0/maint> and F<src/5.0/devel>
85directories.
aa689395 86
7b5757d1 87=head2 Maintenance and Development Subversions
88
f5a32c7f 89The first rule of maintenance work is "First, do no harm."
7b5757d1 90
fb73857a 91Trial releases of bug-fix maintenance releases are announced on
92perl5-porters. Trial releases use the new subversion number (to avoid
93testers installing it over the previous release) and include a 'local
e04b929a 94patch' entry in patchlevel.h. The distribution file contains the
95string C<MAINT_TRIAL> to make clear that the file is not meant for
96public consumption.
fb73857a 97
e04b929a 98In general, the names of official distribution files for the public
f5a32c7f 99always match the regular expression:
e04b929a 100
f5a32c7f 101 ^perl\d+\.(\d+)\.\d+(-MAINT_TRIAL_\d+)\.tar\.gz$
e04b929a 102
f5a32c7f 103C<$1> in the pattern is always an even number for maintenance
104versions, and odd for developer releases.
e04b929a 105
efc41c8e 106In the past it has been observed that pumpkings tend to invent new
e04b929a 107naming conventions on the fly. If you are a pumpking, before you
108invent a new name for any of the three types of perl distributions,
109please inform the guys from the CPAN who are doing indexing and
110provide the trees of symlinks and the like. They will have to know
111I<in advance> what you decide.
20f245af 112
aa689395 113=head2 Why is it called the patch pumpkin?
114
115Chip Salzenberg gets credit for that, with a nod to his cow orker,
116David Croy. We had passed around various names (baton, token, hot
117potato) but none caught on. Then, Chip asked:
118
119[begin quote]
120
121 Who has the patch pumpkin?
122
123To explain: David Croy once told me once that at a previous job,
124there was one tape drive and multiple systems that used it for backups.
125But instead of some high-tech exclusion software, they used a low-tech
126method to prevent multiple simultaneous backups: a stuffed pumpkin.
127No one was allowed to make backups unless they had the "backup pumpkin".
128
129[end quote]
130
131The name has stuck.
132
a6968aa6 133=head1 Philosophical Issues in Patching and Porting Perl
aa689395 134
135There are no absolute rules, but there are some general guidelines I
136have tried to follow as I apply patches to the perl sources.
137(This section is still under construction.)
138
139=head2 Solve problems as generally as possible
140
7b5757d1 141Never implement a specific restricted solution to a problem when you
142can solve the same problem in a more general, flexible way.
143
144For example, for dynamic loading to work on some SVR4 systems, we had
145to build a shared libperl.so library. In order to build "FAT" binaries
146on NeXT 4.0 systems, we had to build a special libperl library. Rather
147than continuing to build a contorted nest of special cases, I
148generalized the process of building libperl so that NeXT and SVR4 users
149could still get their work done, but others could build a shared
150libperl if they wanted to as well.
aa689395 151
a6968aa6 152Contain your changes carefully. Assume nothing about other operating
153systems, not even closely related ones. Your changes must not affect
154other platforms.
155
156Spy shamelessly on how similar patching or porting issues have been
157settled elsewhere.
158
159If feasible, try to keep filenames 8.3-compliant to humor those poor
160souls that get joy from running Perl under such dire limitations.
9e371ce5 161There's a script, check83.pl, for keeping your nose 8.3-clean.
efc41c8e 162In a similar vein, do not create files or directories which differ only
163in case (upper versus lower).
a6968aa6 164
aa689395 165=head2 Seek consensus on major changes
166
167If you are making big changes, don't do it in secret. Discuss the
168ideas in advance on perl5-porters.
169
170=head2 Keep the documentation up-to-date
171
172If your changes may affect how users use perl, then check to be sure
173that the documentation is in sync with your changes. Be sure to
174check all the files F<pod/*.pod> and also the F<INSTALL> document.
175
176Consider writing the appropriate documentation first and then
7b5757d1 177implementing your change to correspond to the documentation.
aa689395 178
179=head2 Avoid machine-specific #ifdef's
180
181To the extent reasonable, try to avoid machine-specific #ifdef's in
182the sources. Instead, use feature-specific #ifdef's. The reason is
183that the machine-specific #ifdef's may not be valid across major
184releases of the operating system. Further, the feature-specific tests
185may help out folks on another platform who have the same problem.
186
a6968aa6 187=head2 Machine-specific files
188
98dddfbd 189=over 4
190
191=item source code
192
a6968aa6 193If you have many machine-specific #defines or #includes, consider
194creating an "osish.h" (os2ish.h, vmsish.h, and so on) and including
195that in perl.h. If you have several machine-specific files (function
196emulations, function stubs, build utility wrappers) you may create a
197separate subdirectory (djgpp, win32) and put the files in there.
98dddfbd 198Remember to update C<MANIFEST> when you add files.
a6968aa6 199
ff935051 200If your system supports dynamic loading but none of the existing
98dddfbd 201methods at F<ext/DynaLoader/dl_*.xs> work for you, you must write
202a new one. Study the existing ones to see what kind of interface
203you must supply.
204
205=item build hints
a6968aa6 206
207There are two kinds of hints: hints for building Perl and hints for
208extensions. The former live in the C<hints> subdirectory, the latter
209in C<ext/*/hints> subdirectories.
210
211The top level hints are Bourne-shell scripts that set, modify and
212unset appropriate Configure variables, based on the Configure command
213line options and possibly existing config.sh and Policy.sh files from
214previous Configure runs.
215
76ba0908 216The extension hints are written in Perl (by the time they are used
a6968aa6 217miniperl has been built) and control the building of their respective
218extensions. They can be used to for example manipulate compilation
219and linking flags.
220
98dddfbd 221=item build and installation Makefiles, scripts, and so forth
222
223Sometimes you will also need to tweak the Perl build and installation
224procedure itself, like for example F<Makefile.SH> and F<installperl>.
225Tread very carefully, even more than usual. Contain your changes
226with utmost care.
a6968aa6 227
98dddfbd 228=item test suite
229
230Many of the tests in C<t> subdirectory assume machine-specific things
a6968aa6 231like existence of certain functions, something about filesystem
232semantics, certain external utilities and their error messages. Use
233the C<$^O> and the C<Config> module (which contains the results of the
234Configure run, in effect the C<config.sh> converted to Perl) to either
98dddfbd 235skip (preferably not) or customize (preferable) the tests for your
236platform.
237
238=item modules
239
240Certain standard modules may need updating if your operating system
241sports for example a native filesystem naming. You may want to update
242some or all of the modules File::Basename, File::Spec, File::Path, and
243File::Copy to become aware of your native filesystem syntax and
244peculiarities.
245
b972f109 246Remember to have a $VERSION in the modules. You can use the
247Porting/checkVERSION.pl script for checking this.
248
98dddfbd 249=item documentation
250
251If your operating system comes from outside UNIX you almost certainly
252will have differences in the available operating system functionality
253(missing system calls, different semantics, whatever). Please
254document these at F<pod/perlport.pod>. If your operating system is
255the first B<not> to have a system call also update the list of
256"portability-bewares" at the beginning of F<pod/perlfunc.pod>.
257
258A file called F<README.youros> at the top level that explains things
259like how to install perl at this platform, where to get any possibly
260required additional software, and for example what test suite errors
76ba0908 261to expect, is nice too. Such files are in the process of being written
262in pod format and will eventually be renamed F<INSTALL.youros>.
98dddfbd 263
264You may also want to write a separate F<.pod> file for your operating
265system to tell about existing mailing lists, os-specific modules,
266documentation, whatever. Please name these along the lines of
267F<perl>I<youros>.pod. [unfinished: where to put this file (the pod/
268subdirectory, of course: but more importantly, which/what index files
269should be updated?)]
270
271=back
a6968aa6 272
aa689395 273=head2 Allow for lots of testing
274
275We should never release a main version without testing it as a
276subversion first.
277
6877a1cf 278=head2 Test popular applications and modules.
279
280We should never release a main version without testing whether or not
281it breaks various popular modules and applications. A partial list of
282such things would include majordomo, metaconfig, apache, Tk, CGI,
283libnet, and libwww, to name just a few. Of course it's quite possible
284that some of those things will be just plain broken and need to be fixed,
285but, in general, we ought to try to avoid breaking widely-installed
286things.
287
98dddfbd 288=head2 Automated generation of derivative files
aa689395 289
290The F<embed.h>, F<keywords.h>, F<opcode.h>, and F<perltoc.pod> files
291are all automatically generated by perl scripts. In general, don't
292patch these directly; patch the data files instead.
293
294F<Configure> and F<config_h.SH> are also automatically generated by
295B<metaconfig>. In general, you should patch the metaconfig units
a6968aa6 296instead of patching these files directly. However, very minor changes
297to F<Configure> may be made in between major sync-ups with the
298metaconfig units, which tends to be complicated operations. But be
299careful, this can quickly spiral out of control. Running metaconfig
300is not really hard.
aa689395 301
98dddfbd 302Also F<Makefile> is automatically produced from F<Makefile.SH>.
303In general, look out for all F<*.SH> files.
304
a8119d38 305Finally, the sample files in the F<Porting/> subdirectory are
306generated automatically by the script F<U/mksample> included
307with the metaconfig units. See L<"run metaconfig"> below for
308information on obtaining the metaconfig units.
309
aa689395 310=head1 How to Make a Distribution
311
312There really ought to be a 'make dist' target, but there isn't.
313The 'dist' suite of tools also contains a number of tools that I haven't
314learned how to use yet. Some of them may make this all a bit easier.
315
316Here are the steps I go through to prepare a patch & distribution.
317
3e3baf6d 318Lots of it could doubtless be automated but isn't. The Porting/makerel
319(make release) perl script does now help automate some parts of it.
aa689395 320
321=head2 Announce your intentions
322
323First, you should volunteer out loud to take the patch pumpkin. It's
324generally counter-productive to have multiple people working in secret
325on the same thing.
326
327At the same time, announce what you plan to do with the patch pumpkin,
328to allow folks a chance to object or suggest alternatives, or do it for
329you. Naturally, the patch pumpkin holder ought to incorporate various
330bug fixes and documentation improvements that are posted while he or
331she has the pumpkin, but there might also be larger issues at stake.
332
333One of the precepts of the subversion idea is that we shouldn't give
7b5757d1 334the patch pumpkin to anyone unless we have some idea what he or she
335is going to do with it.
aa689395 336
337=head2 refresh pod/perltoc.pod
338
339Presumably, you have done a full C<make> in your working source
340directory. Before you C<make spotless> (if you do), and if you have
341changed any documentation in any module or pod file, change to the
342F<pod> directory and run C<make toc>.
343
3e3baf6d 344=head2 run installhtml to check the validity of the pod files
345
aa689395 346=head2 update patchlevel.h
347
348Don't be shy about using the subversion number, even for a relatively
349modest patch. We've never even come close to using all 99 subversions,
350and it's better to have a distinctive number for your patch. If you
351need feedback on your patch, go ahead and issue it and promise to
352incorporate that feedback quickly (e.g. within 1 week) and send out a
353second patch.
354
05ff1fbb 355If you update the subversion number, you may need to change the version
356number near the top of the F<Changes> file.
357
aa689395 358=head2 run metaconfig
359
360If you need to make changes to Configure or config_h.SH, it may be best to
361change the appropriate metaconfig units instead, and regenerate Configure.
362
363 metaconfig -m
364
20f245af 365will regenerate Configure and config_h.SH. Much more information
366on obtaining and running metaconfig is in the F<U/README> file
449b893f 367that comes with Perl's metaconfig units.
368
369Since metaconfig is hard to change, running correction scripts after
370this generation is sometimes needed. Configure gained complexity over
371time, and the order in which config_h.SH is generated can cause havoc
372when compiling perl. Therefor, you need to run Porting/config_h.pl
373after that generation. All that and more is described in the README
374files that come with the metaunits.
375
376Perl's metaconfig units should be available on CPAN. A set of units
377that will work with perl5.9.x is in a file with a name similar to
378F<mc_units-20070423.tgz> under http://www.cpan.org/authors/id/H/HM/HMBRAND/ .
379The mc_units tar file should be unpacked in your main perl source directory.
380Note: those units were for use with 5.9.x. There may have been changes since
381then. Check for later versions or contact perl5-porters@perl.org to obtain a
20f245af 382pointer to the current version.
aa689395 383
449b893f 384Alternatively, do consider if the F<*ish.h> files or the hint files might be
385a better place for your changes.
aa689395 386
387=head2 MANIFEST
388
389Make sure the MANIFEST is up-to-date. You can use dist's B<manicheck>
390program for this. You can also use
391
3e3baf6d 392 perl -w -MExtUtils::Manifest=fullcheck -e fullcheck
aa689395 393
3e3baf6d 394Both commands will also list extra files in the directory that are not
395listed in MANIFEST.
aa689395 396
bfb7748a 397The MANIFEST is normally sorted.
aa689395 398
399If you are using metaconfig to regenerate Configure, then you should note
400that metaconfig actually uses MANIFEST.new, so you want to be sure
401MANIFEST.new is up-to-date too. I haven't found the MANIFEST/MANIFEST.new
402distinction particularly useful, but that's probably because I still haven't
403learned how to use the full suite of tools in the dist distribution.
404
405=head2 Check permissions
406
407All the tests in the t/ directory ought to be executable. The
408main makefile used to do a 'chmod t/*/*.t', but that resulted in
409a self-modifying distribution--something some users would strongly
d562869c 410prefer to avoid. The F<t/TEST> script will check for this
411and do the chmod if needed, but the tests still ought to be
412executable.
aa689395 413
414In all, the following files should probably be executable:
415
416 Configure
417 configpm
32fcaa0b 418 configure.gnu
aa689395 419 embed.pl
420 installperl
421 installman
422 keywords.pl
aa689395 423 myconfig
424 opcode.pl
aa689395 425 t/TEST
426 t/*/*.t
427 *.SH
428 vms/ext/Stdio/test.pl
429 vms/ext/filespec.t
aa689395 430 x2p/*.SH
431
432Other things ought to be readable, at least :-).
433
434Probably, the permissions for the files could be encoded in MANIFEST
435somehow, but I'm reluctant to change MANIFEST itself because that
436could break old scripts that use MANIFEST.
437
438I seem to recall that some SVR3 systems kept some sort of file that listed
439permissions for system files; something like that might be appropriate.
440
441=head2 Run Configure
442
443This will build a config.sh and config.h. You can skip this if you haven't
693762b4 444changed Configure or config_h.SH at all. I use the following command
aa689395 445
693762b4 446 sh Configure -Dprefix=/opt/perl -Doptimize=-O -Dusethreads \
447 -Dcf_by='yourname' \
448 -Dcf_email='yourname@yourhost.yourplace.com' \
449 -Dperladmin='yourname@yourhost.yourplace.com' \
450 -Dmydomain='.yourplace.com' \
451 -Dmyhostname='yourhost' \
452 -des
aa689395 453
693762b4 454=head2 Update Porting/config.sh and Porting/config_H
dfe9444c 455
693762b4 456[XXX
457This section needs revision. We're currently working on easing
458the task of keeping the vms, win32, and plan9 config.sh info
459up-to-date. The plan is to use keep up-to-date 'canned' config.sh
460files in the appropriate subdirectories and then generate 'canned'
461config.h files for vms, win32, etc. from the generic config.sh file.
462This is to ease maintenance. When Configure gets updated, the parts
463sometimes get scrambled around, and the changes in config_H can
464sometimes be very hard to follow. config.sh, on the other hand, can
465safely be sorted, so it's easy to track (typically very small) changes
d7f8936a 466to config.sh and then propagate them to a canned 'config.h' by any
693762b4 467number of means, including a perl script in win32/ or carrying
468config.sh and config_h.SH to a Unix system and running sh
76ba0908 469config_h.SH.) Vms uses configure.com to generate its own config.sh
470and config.h. If you want to add a new variable to config.sh check
471with vms folk how to add it to configure.com too.
693762b4 472XXX]
473
474The Porting/config.sh and Porting/config_H files are provided to
475help those folks who can't run Configure. It is important to keep
476them up-to-date. If you have changed config_h.SH, those changes must
477be reflected in config_H as well. (The name config_H was chosen to
478distinguish the file from config.h even on case-insensitive file systems.)
479Simply edit the existing config_H file; keep the first few explanatory
480lines and then copy your new config.h below.
aa689395 481
76ba0908 482It may also be necessary to update win32/config.?c, and
aa689395 483plan9/config.plan9, though you should be quite careful in doing so if
484you are not familiar with those systems. You might want to issue your
485patch with a promise to quickly issue a follow-up that handles those
486directories.
487
0de566d7 488=head2 make regen_perly
aa689395 489
d7f8936a 490If perly.y has been edited, it is necessary to run this target to rebuild
d21142e6 491perly.h, perly.act and perly.tab. In fact this target just runs the Perl
492script regen_perly.pl. Note that perly.c is I<not> rebuilt; this is just a
0de566d7 493plain static file now.
aa689395 494
0de566d7 495This target relies on you having Bison installed on your system. Running
496the target will tell you if you haven't got the right version, and if so,
497where to get the right one. Or if you prefer, you could hack
498regen_perly.pl to work with your version of Bison. The important things
499are that the regexes can still extract out the right chunks of the Bison
d21142e6 500output into perly.act and perly.tab, and that the contents of those two
0de566d7 501files, plus perly.h, are functionally equivalent to those produced by the
502supported version of Bison.
ebb99254 503
0de566d7 504Note that in the old days, you had to do C<make run_byacc> instead.
aa689395 505
76ba0908 506=head2 make regen_all
507
0de566d7 508This target takes care of the regen_headers, and regen_pods targets.
76ba0908 509
aa689395 510=head2 make regen_headers
511
512The F<embed.h>, F<keywords.h>, and F<opcode.h> files are all automatically
513generated by perl scripts. Since the user isn't guaranteed to have a
514working perl, we can't require the user to generate them. Hence you have
515to, if you're making a distribution.
516
517I used to include rules like the following in the makefile:
518
519 # The following three header files are generated automatically
520 # The correct versions should be already supplied with the perl kit,
521 # in case you don't have perl or 'sh' available.
522 # The - is to ignore error return codes in case you have the source
523 # installed read-only or you don't have perl yet.
524 keywords.h: keywords.pl
525 @echo "Don't worry if this fails."
526 - perl keywords.pl
527
528
7b5757d1 529However, I got B<lots> of mail consisting of people worrying because the
aa689395 530command failed. I eventually decided that I would save myself time
531and effort by manually running C<make regen_headers> myself rather
532than answering all the questions and complaints about the failing
533command.
534
76ba0908 535=head2 make regen_pods
536
537Will run `make regen_pods` in the pod directory for indexing.
538
3e3baf6d 539=head2 global.sym, interp.sym and perlio.sym
aa689395 540
541Make sure these files are up-to-date. Read the comments in these
542files and in perl_exp.SH to see what to do.
543
544=head2 Binary compatibility
545
546If you do change F<global.sym> or F<interp.sym>, think carefully about
547what you are doing. To the extent reasonable, we'd like to maintain
76ba0908 548source and binary compatibility with older releases of perl. That way,
aa689395 549extensions built under one version of perl will continue to work with
550new versions of perl.
551
552Of course, some incompatible changes may well be necessary. I'm just
553suggesting that we not make any such changes without thinking carefully
554about them first. If possible, we should provide
555backwards-compatibility stubs. There's a lot of XS code out there.
556Let's not force people to keep changing it.
557
d65aee78 558=head2 PPPort
559
560F<ext/Devel/PPPort/PPPort.pm> needs to be synchronized to include all
561new macros added to .h files (normally perl.h and XSUB.h, but others
562as well). Since chances are that when a new macro is added the
563committer will forget to update F<PPPort.pm>, it's the best to diff for
564changes in .h files when making a new release and making sure that
565F<PPPort.pm> contains them all.
566
567The pumpking can delegate the synchronization responsibility to anybody
568else, but the release process is the only place where we can make sure
569that no new macros fell through the cracks.
570
aa689395 571=head2 Changes
572
573Be sure to update the F<Changes> file. Try to include both an overall
574summary as well as detailed descriptions of the changes. Your
3e3baf6d 575audience will include other developers and users, so describe
aa689395 576user-visible changes (if any) in terms they will understand, not in
577code like "initialize foo variable in bar function".
578
579There are differing opinions on whether the detailed descriptions
580ought to go in the Changes file or whether they ought to be available
581separately in the patch file (or both). There is no disagreement that
582detailed descriptions ought to be easily available somewhere.
583
05ff1fbb 584If you update the subversion number in F<patchlevel.h>, you may need
585to change the version number near the top of the F<Changes> file.
586
2a26e2f1 587=head2 Todo
588
efc41c8e 589The F<pod/perltodo.pod> file contains a roughly-categorized unordered
590list of aspects of Perl that could use enhancement, features that could
591be added, areas that could be cleaned up, and so on. During your term
592as pumpkin-holder, you will probably address some of these issues, and
593perhaps identify others which, while you decide not to address them this
594time around, may be tackled in the future. Update the file to reflect
595the situation as it stands when you hand over the pumpkin.
2a26e2f1 596
597You might like, early in your pumpkin-holding career, to see if you
d7f8936a 598can find champions for particular issues on the to-do list: an issue
2a26e2f1 599owned is an issue more likely to be resolved.
600
94655993 601There are also some more porting-specific L</Todo> items later in this
c4f23d77 602file.
603
aa689395 604=head2 OS/2-specific updates
605
606In the os2 directory is F<diff.configure>, a set of OS/2-specific
607diffs against B<Configure>. If you make changes to Configure, you may
608want to consider regenerating this diff file to save trouble for the
609OS/2 maintainer.
610
7b5757d1 611You can also consider the OS/2 diffs as reminders of portability
612things that need to be fixed in Configure.
613
aa689395 614=head2 VMS-specific updates
615
76ba0908 616The Perl revision number appears as "perl5" in configure.com.
617It is courteous to update that if necessary.
aa689395 618
619=head2 Making the new distribution
620
621Suppose, for example, that you want to make version 5.004_08. Then you can
622do something like the following
623
624 mkdir ../perl5.004_08
625 awk '{print $1}' MANIFEST | cpio -pdm ../perl5.004_08
626 cd ../
627 tar cf perl5.004_08.tar perl5.004_08
628 gzip --best perl5.004_08.tar
629
3e3baf6d 630These steps, with extra checks, are automated by the Porting/makerel
631script.
632
aa689395 633=head2 Making a new patch
634
635I find the F<makepatch> utility quite handy for making patches.
636You can obtain it from any CPAN archive under
a93751fa 637http://www.cpan.org/authors/Johan_Vromans/ . There are a couple
3e3baf6d 638of differences between my version and the standard one. I have mine do
639a
aa689395 640
641 # Print a reassuring "End of Patch" note so people won't
642 # wonder if their mailer truncated patches.
643 print "\n\nEnd of Patch.\n";
644
3e3baf6d 645at the end. That's because I used to get questions from people asking
646if their mail was truncated.
647
648It also writes Index: lines which include the new directory prefix
649(change Index: print, approx line 294 or 310 depending on the version,
650to read: print PATCH ("Index: $newdir$new\n");). That helps patches
651work with more POSIX conformant patch programs.
aa689395 652
653Here's how I generate a new patch. I'll use the hypothetical
6545.004_07 to 5.004_08 patch as an example.
655
656 # unpack perl5.004_07/
657 gzip -d -c perl5.004_07.tar.gz | tar -xof -
658 # unpack perl5.004_08/
659 gzip -d -c perl5.004_08.tar.gz | tar -xof -
660 makepatch perl5.004_07 perl5.004_08 > perl5.004_08.pat
661
662Makepatch will automatically generate appropriate B<rm> commands to remove
663deleted files. Unfortunately, it will not correctly set permissions
664for newly created files, so you may have to do so manually. For example,
665patch 5.003_04 created a new test F<t/op/gv.t> which needs to be executable,
666so at the top of the patch, I inserted the following lines:
667
668 # Make a new test
669 touch t/op/gv.t
670 chmod +x t/opt/gv.t
671
672Now, of course, my patch is now wrong because makepatch didn't know I
673was going to do that command, and it patched against /dev/null.
674
675So, what I do is sort out all such shell commands that need to be in the
676patch (including possible mv-ing of files, if needed) and put that in the
677shell commands at the top of the patch. Next, I delete all the patch parts
678of perl5.004_08.pat, leaving just the shell commands. Then, I do the
679following:
680
7b5757d1 681 cd perl5.004_07
682 sh ../perl5.004_08.pat
aa689395 683 cd ..
7b5757d1 684 makepatch perl5.004_07 perl5.004_08 >> perl5.004_08.pat
aa689395 685
686(Note the append to preserve my shell commands.)
687Now, my patch will line up with what the end users are going to do.
688
689=head2 Testing your patch
690
691It seems obvious, but be sure to test your patch. That is, verify that
692it produces exactly the same thing as your full distribution.
693
7b5757d1 694 rm -rf perl5.004_07
695 gzip -d -c perl5.004_07.tar.gz | tar -xf -
696 cd perl5.004_07
697 sh ../perl5.004_08.pat
698 patch -p1 -N < ../perl5.004_08.pat
aa689395 699 cd ..
7b5757d1 700 gdiff -r perl5.004_07 perl5.004_08
aa689395 701
702where B<gdiff> is GNU diff. Other diff's may also do recursive checking.
703
704=head2 More testing
705
706Again, it's obvious, but you should test your new version as widely as you
707can. You can be sure you'll hear about it quickly if your version doesn't
708work on both ANSI and pre-ANSI compilers, and on common systems such as
709SunOS 4.1.[34], Solaris, and Linux.
710
711If your changes include conditional code, try to test the different
712branches as thoroughly as you can. For example, if your system
713supports dynamic loading, you can also test static loading with
714
715 sh Configure -Uusedl
716
717You can also hand-tweak your config.h to try out different #ifdef
718branches.
719
d2560b70 720=head2 Other tests
721
00baac8f 722=over 4
723
93189314 724=item gcc -ansi -pedantic
725
726Configure -Dgccansipedantic [ -Dcc=gcc ] will enable (via the cflags script,
727not $Config{ccflags}) the gcc strict ANSI C flags -ansi and -pedantic for
728the compilation of the core files on platforms where it knows it can
729do so (like Linux, see cflags.SH for the full list), and on some
730platforms only one (Solaris can do only -pedantic, not -ansi).
731The flag -DPERL_GCC_PEDANTIC also gets added, since gcc does not add
732any internal cpp flag to signify that -pedantic is being used, as it
733does for -ansi (__STRICT_ANSI__).
734
a0426075 735Note that the -ansi and -pedantic are enabled only for version 3 (and
736later) of gcc, since even gcc version 2.95.4 finds lots of seemingly
737false "value computed not used" errors from Perl.
738
93189314 739The -ansi and -pedantic are useful in catching at least the following
740nonportable practices:
741
742=over 4
743
744=item *
745
746gcc-specific extensions
747
748=item *
749
750lvalue casts
751
752=item *
753
754// C++ comments
755
756=item *
757
758enum trailing commas
759
760=back
761
762The -Dgccansipedantic should be used only when cleaning up the code,
763not for production builds, since otherwise gcc cannot inline certain
764things.
765
d2560b70 766=back
767
d33b2eba 768=head1 Running Purify
f5a32c7f 769
770Purify is a commercial tool that is helpful in identifying memory
771overruns, wild pointers, memory leaks and other such badness. Perl
772must be compiled in a specific way for optimal testing with Purify.
773
774Use the following commands to test perl with Purify:
775
776 sh Configure -des -Doptimize=-g -Uusemymalloc -Dusemultiplicity \
777 -Accflags=-DPURIFY
778 setenv PURIFYOPTIONS "-chain-length=25"
779 make all pureperl
780 cd t
781 ln -s ../pureperl perl
365a6279 782 setenv PERL_DESTRUCT_LEVEL 2
f5a32c7f 783 ./perl TEST
784
785Disabling Perl's malloc allows Purify to monitor allocations and leaks
786more closely; using Perl's malloc will make Purify report most leaks
787in the "potential" leaks category. Enabling the multiplicity option
788allows perl to clean up thoroughly when the interpreter shuts down, which
789reduces the number of bogus leak reports from Purify. The -DPURIFY
790enables any Purify-specific debugging code in the sources.
791
792Purify outputs messages in "Viewer" windows by default. If you don't have
793a windowing environment or if you simply want the Purify output to
794unobtrusively go to a log file instead of to the interactive window,
795use the following options instead:
796
797 setenv PURIFYOPTIONS "-chain-length=25 -windows=no -log-file=perl.log \
798 -append-logfile=yes"
799
800The only currently known leaks happen when there are compile-time errors
801within eval or require. (Fixing these is non-trivial, unfortunately, but
802they must be fixed eventually.)
803
b432a672 804=head1 Common Gotchas
aa689395 805
806=over 4
807
aa689395 808=item Probably Prefer POSIX
809
810It's often the case that you'll need to choose whether to do
811something the BSD-ish way or the POSIX-ish way. It's usually not
812a big problem when the two systems use different names for similar
813functions, such as memcmp() and bcmp(). The perl.h header file
814handles these by appropriate #defines, selecting the POSIX mem*()
815functions if available, but falling back on the b*() functions, if
816need be.
817
818More serious is the case where some brilliant person decided to
819use the same function name but give it a different meaning or
820calling sequence :-). getpgrp() and setpgrp() come to mind.
821These are a real problem on systems that aim for conformance to
822one standard (e.g. POSIX), but still try to support the other way
823of doing things (e.g. BSD). My general advice (still not really
824implemented in the source) is to do something like the following.
825Suppose there are two alternative versions, fooPOSIX() and
826fooBSD().
827
828 #ifdef HAS_FOOPOSIX
829 /* use fooPOSIX(); */
830 #else
831 # ifdef HAS_FOOBSD
832 /* try to emulate fooPOSIX() with fooBSD();
833 perhaps with the following: */
834 # define fooPOSIX fooBSD
835 # else
836 # /* Uh, oh. We have to supply our own. */
837 # define fooPOSIX Perl_fooPOSIX
838 # endif
839 #endif
840
841=item Think positively
842
843If you need to add an #ifdef test, it is usually easier to follow if you
844think positively, e.g.
845
846 #ifdef HAS_NEATO_FEATURE
847 /* use neato feature */
848 #else
849 /* use some fallback mechanism */
850 #endif
851
852rather than the more impenetrable
853
854 #ifndef MISSING_NEATO_FEATURE
855 /* Not missing it, so we must have it, so use it */
856 #else
857 /* Are missing it, so fall back on something else. */
858 #endif
859
860Of course for this toy example, there's not much difference. But when
861the #ifdef's start spanning a couple of screen fulls, and the #else's
862are marked something like
863
864 #else /* !MISSING_NEATO_FEATURE */
865
866I find it easy to get lost.
867
868=item Providing Missing Functions -- Problem
869
870Not all systems have all the neat functions you might want or need, so
871you might decide to be helpful and provide an emulation. This is
872sound in theory and very kind of you, but please be careful about what
873you name the function. Let me use the C<pause()> function as an
874illustration.
875
876Perl5.003 has the following in F<perl.h>
877
878 #ifndef HAS_PAUSE
879 #define pause() sleep((32767<<16)+32767)
880 #endif
881
882Configure sets HAS_PAUSE if the system has the pause() function, so
883this #define only kicks in if the pause() function is missing.
884Nice idea, right?
885
886Unfortunately, some systems apparently have a prototype for pause()
887in F<unistd.h>, but don't actually have the function in the library.
888(Or maybe they do have it in a library we're not using.)
889
890Thus, the compiler sees something like
891
892 extern int pause(void);
893 /* . . . */
894 #define pause() sleep((32767<<16)+32767)
895
896and dies with an error message. (Some compilers don't mind this;
897others apparently do.)
898
899To work around this, 5.003_03 and later have the following in perl.h:
900
901 /* Some unistd.h's give a prototype for pause() even though
902 HAS_PAUSE ends up undefined. This causes the #define
903 below to be rejected by the compiler. Sigh.
904 */
905 #ifdef HAS_PAUSE
906 # define Pause pause
907 #else
908 # define Pause() sleep((32767<<16)+32767)
909 #endif
910
911This works.
912
913The curious reader may wonder why I didn't do the following in
914F<util.c> instead:
915
916 #ifndef HAS_PAUSE
917 void pause()
918 {
919 sleep((32767<<16)+32767);
920 }
921 #endif
922
923That is, since the function is missing, just provide it.
924Then things would probably be been alright, it would seem.
925
926Well, almost. It could be made to work. The problem arises from the
927conflicting needs of dynamic loading and namespace protection.
928
929For dynamic loading to work on AIX (and VMS) we need to provide a list
930of symbols to be exported. This is done by the script F<perl_exp.SH>,
931which reads F<global.sym> and F<interp.sym>. Thus, the C<pause>
932symbol would have to be added to F<global.sym> So far, so good.
933
934On the other hand, one of the goals of Perl5 is to make it easy to
935either extend or embed perl and link it with other libraries. This
936means we have to be careful to keep the visible namespace "clean".
937That is, we don't want perl's global variables to conflict with
938those in the other application library. Although this work is still
939in progress, the way it is currently done is via the F<embed.h> file.
940This file is built from the F<global.sym> and F<interp.sym> files,
941since those files already list the globally visible symbols. If we
942had added C<pause> to global.sym, then F<embed.h> would contain the
943line
944
945 #define pause Perl_pause
946
947and calls to C<pause> in the perl sources would now point to
948C<Perl_pause>. Now, when B<ld> is run to build the F<perl> executable,
949it will go looking for C<perl_pause>, which probably won't exist in any
950of the standard libraries. Thus the build of perl will fail.
951
952Those systems where C<HAS_PAUSE> is not defined would be ok, however,
953since they would get a C<Perl_pause> function in util.c. The rest of
954the world would be in trouble.
955
956And yes, this scenario has happened. On SCO, the function C<chsize>
957is available. (I think it's in F<-lx>, the Xenix compatibility
958library.) Since the perl4 days (and possibly before), Perl has
959included a C<chsize> function that gets called something akin to
960
961 #ifndef HAS_CHSIZE
962 I32 chsize(fd, length)
963 /* . . . */
964 #endif
965
966When 5.003 added
967
968 #define chsize Perl_chsize
969
970to F<embed.h>, the compile started failing on SCO systems.
971
972The "fix" is to give the function a different name. The one
973implemented in 5.003_05 isn't optimal, but here's what was done:
974
975 #ifdef HAS_CHSIZE
976 # ifdef my_chsize /* Probably #defined to Perl_my_chsize in embed.h */
977 # undef my_chsize
978 # endif
979 # define my_chsize chsize
980 #endif
981
982My explanatory comment in patch 5.003_05 said:
983
984 Undef and then re-define my_chsize from Perl_my_chsize to
985 just plain chsize if this system HAS_CHSIZE. This probably only
986 applies to SCO. This shows the perils of having internal
987 functions with the same name as external library functions :-).
988
989Now, we can safely put C<my_chsize> in F<global.sym>, export it, and
990hide it with F<embed.h>.
991
992To be consistent with what I did for C<pause>, I probably should have
993called the new function C<Chsize>, rather than C<my_chsize>.
994However, the perl sources are quite inconsistent on this (Consider
995New, Mymalloc, and Myremalloc, to name just a few.)
996
997There is a problem with this fix, however, in that C<Perl_chsize>
998was available as a F<libperl.a> library function in 5.003, but it
999isn't available any more (as of 5.003_07). This means that we've
1000broken binary compatibility. This is not good.
1001
1002=item Providing missing functions -- some ideas
1003
1004We currently don't have a standard way of handling such missing
1005function names. Right now, I'm effectively thinking aloud about a
1006solution. Some day, I'll try to formally propose a solution.
1007
1008Part of the problem is that we want to have some functions listed as
1009exported but not have their names mangled by embed.h or possibly
1010conflict with names in standard system headers. We actually already
1011have such a list at the end of F<perl_exp.SH> (though that list is
1012out-of-date):
1013
1014 # extra globals not included above.
1015 cat <<END >> perl.exp
1016 perl_init_ext
1017 perl_init_fold
1018 perl_init_i18nl14n
1019 perl_alloc
1020 perl_construct
1021 perl_destruct
1022 perl_free
1023 perl_parse
1024 perl_run
1025 perl_get_sv
1026 perl_get_av
1027 perl_get_hv
1028 perl_get_cv
1029 perl_call_argv
1030 perl_call_pv
1031 perl_call_method
1032 perl_call_sv
1033 perl_requirepv
1034 safecalloc
1035 safemalloc
1036 saferealloc
1037 safefree
1038
1039This still needs much thought, but I'm inclined to think that one
1040possible solution is to prefix all such functions with C<perl_> in the
1041source and list them along with the other C<perl_*> functions in
1042F<perl_exp.SH>.
1043
1044Thus, for C<chsize>, we'd do something like the following:
1045
1046 /* in perl.h */
1047 #ifdef HAS_CHSIZE
1048 # define perl_chsize chsize
1049 #endif
1050
1051then in some file (e.g. F<util.c> or F<doio.c>) do
1052
1053 #ifndef HAS_CHSIZE
1054 I32 perl_chsize(fd, length)
1055 /* implement the function here . . . */
1056 #endif
1057
1058Alternatively, we could just always use C<chsize> everywhere and move
1059C<chsize> from F<global.sym> to the end of F<perl_exp.SH>. That would
1060probably be fine as long as our C<chsize> function agreed with all the
1061C<chsize> function prototypes in the various systems we'll be using.
1062As long as the prototypes in actual use don't vary that much, this is
1063probably a good alternative. (As a counter-example, note how Configure
1064and perl have to go through hoops to find and use get Malloc_t and
1065Free_t for C<malloc> and C<free>.)
1066
1067At the moment, this latter option is what I tend to prefer.
1068
1069=item All the world's a VAX
1070
1071Sorry, showing my age:-). Still, all the world is not BSD 4.[34],
1072SVR4, or POSIX. Be aware that SVR3-derived systems are still quite
1073common (do you have any idea how many systems run SCO?) If you don't
1074have a bunch of v7 manuals handy, the metaconfig units (by default
1075installed in F</usr/local/lib/dist/U>) are a good resource to look at
1076for portability.
1077
1078=back
1079
1080=head1 Miscellaneous Topics
1081
1082=head2 Autoconf
1083
1084Why does perl use a metaconfig-generated Configure script instead of an
1085autoconf-generated configure script?
1086
1087Metaconfig and autoconf are two tools with very similar purposes.
1088Metaconfig is actually the older of the two, and was originally written
1089by Larry Wall, while autoconf is probably now used in a wider variety of
1090packages. The autoconf info file discusses the history of autoconf and
1091how it came to be. The curious reader is referred there for further
1092information.
1093
1094Overall, both tools are quite good, I think, and the choice of which one
1095to use could be argued either way. In March, 1994, when I was just
1096starting to work on Configure support for Perl5, I considered both
1097autoconf and metaconfig, and eventually decided to use metaconfig for the
1098following reasons:
1099
1100=over 4
1101
1102=item Compatibility with Perl4
1103
1104Perl4 used metaconfig, so many of the #ifdef's were already set up for
1105metaconfig. Of course metaconfig had evolved some since Perl4's days,
1106but not so much that it posed any serious problems.
1107
1108=item Metaconfig worked for me
1109
d1be9408 1110My system at the time was Interactive 2.2, an SVR3.2/386 derivative that
aa689395 1111also had some POSIX support. Metaconfig-generated Configure scripts
1112worked fine for me on that system. On the other hand, autoconf-generated
1113scripts usually didn't. (They did come quite close, though, in some
1114cases.) At the time, I actually fetched a large number of GNU packages
1115and checked. Not a single one configured and compiled correctly
1116out-of-the-box with the system's cc compiler.
1117
1118=item Configure can be interactive
1119
1120With both autoconf and metaconfig, if the script works, everything is
1121fine. However, one of my main problems with autoconf-generated scripts
1122was that if it guessed wrong about something, it could be B<very> hard to
1123go back and fix it. For example, autoconf always insisted on passing the
1124-Xp flag to cc (to turn on POSIX behavior), even when that wasn't what I
1125wanted or needed for that package. There was no way short of editing the
1126configure script to turn this off. You couldn't just edit the resulting
1127Makefile at the end because the -Xp flag influenced a number of other
1128configure tests.
1129
1130Metaconfig's Configure scripts, on the other hand, can be interactive.
1131Thus if Configure is guessing things incorrectly, you can go back and fix
1132them. This isn't as important now as it was when we were actively
1133developing Configure support for new features such as dynamic loading,
1134but it's still useful occasionally.
1135
1136=item GPL
1137
1138At the time, autoconf-generated scripts were covered under the GNU Public
1139License, and hence weren't suitable for inclusion with Perl, which has a
1140different licensing policy. (Autoconf's licensing has since changed.)
1141
1142=item Modularity
1143
1144Metaconfig builds up Configure from a collection of discrete pieces
1145called "units". You can override the standard behavior by supplying your
1146own unit. With autoconf, you have to patch the standard files instead.
1147I find the metaconfig "unit" method easier to work with. Others
1148may find metaconfig's units clumsy to work with.
1149
1150=back
1151
aa689395 1152=head2 Why isn't there a directory to override Perl's library?
1153
1154Mainly because no one's gotten around to making one. Note that
1155"making one" involves changing perl.c, Configure, config_h.SH (and
1156associated files, see above), and I<documenting> it all in the
1157INSTALL file.
1158
1159Apparently, most folks who want to override one of the standard library
1160files simply do it by overwriting the standard library files.
1161
1162=head2 APPLLIB
1163
1164In the perl.c sources, you'll find an undocumented APPLLIB_EXP
1165variable, sort of like PRIVLIB_EXP and ARCHLIB_EXP (which are
1166documented in config_h.SH). Here's what APPLLIB_EXP is for, from
1167a mail message from Larry:
1168
1169 The main intent of APPLLIB_EXP is for folks who want to send out a
1170 version of Perl embedded in their product. They would set the symbol
1171 to be the name of the library containing the files needed to run or to
1172 support their particular application. This works at the "override"
1173 level to make sure they get their own versions of any library code that
1174 they absolutely must have configuration control over.
1175
1176 As such, I don't see any conflict with a sysadmin using it for a
1177 override-ish sort of thing, when installing a generic Perl. It should
1178 probably have been named something to do with overriding though. Since
1179 it's undocumented we could still change it... :-)
1180
24f415b4 1181Given that it's already there, you can use it to override distribution modules.
1182One way to do that is to add
1183
453a1e5f 1184 ccflags="$ccflags -DAPPLLIB_EXP=\"/my/override\""
24f415b4 1185
1186to your config.over file. (You have to be particularly careful to get the
453a1e5f 1187double quotes in. APPLLIB_EXP must be a valid C string. It might
1188actually be easier to just #define it yourself in perl.c.)
24f415b4 1189
1190Then perl.c will put /my/override ahead of ARCHLIB and PRIVLIB. Perl will
1191also search architecture-specific and version-specific subdirectories of
1192APPLLIB_EXP.
aa689395 1193
c4f23d77 1194=head2 Shared libperl.so location
1195
1196Why isn't the shared libperl.so installed in /usr/lib/ along
1197with "all the other" shared libraries? Instead, it is installed
1198in $archlib, which is typically something like
1199
1200 /usr/local/lib/perl5/archname/5.00404
1201
1202and is architecture- and version-specific.
1203
1204The basic reason why a shared libperl.so gets put in $archlib is so that
1205you can have more than one version of perl on the system at the same time,
1206and have each refer to its own libperl.so.
1207
1208Three examples might help. All of these work now; none would work if you
1209put libperl.so in /usr/lib.
1210
1211=over
1212
1213=item 1.
1214
1215Suppose you want to have both threaded and non-threaded perl versions
1216around. Configure will name both perl libraries "libperl.so" (so that
1217you can link to them with -lperl). The perl binaries tell them apart
1218by having looking in the appropriate $archlib directories.
1219
1220=item 2.
1221
1222Suppose you have perl5.004_04 installed and you want to try to compile
1223it again, perhaps with different options or after applying a patch.
1224If you already have libperl.so installed in /usr/lib/, then it may be
1225either difficult or impossible to get ld.so to find the new libperl.so
1226that you're trying to build. If, instead, libperl.so is tucked away in
1227$archlib, then you can always just change $archlib in the current perl
1228you're trying to build so that ld.so won't find your old libperl.so.
1229(The INSTALL file suggests you do this when building a debugging perl.)
1230
1231=item 3.
1232
1233The shared perl library is not a "well-behaved" shared library with
1234proper major and minor version numbers, so you can't necessarily
1235have perl5.004_04 and perl5.004_05 installed simultaneously. Suppose
1236perl5.004_04 were to install /usr/lib/libperl.so.4.4, and perl5.004_05
1237were to install /usr/lib/libperl.so.4.5. Now, when you try to run
1238perl5.004_04, ld.so might try to load libperl.so.4.5, since it has
1239the right "major version" number. If this works at all, it almost
1240certainly defeats the reason for keeping perl5.004_04 around. Worse,
1241with development subversions, you certaily can't guarantee that
1242libperl.so.4.4 and libperl.so.4.55 will be compatible.
1243
1244Anyway, all this leads to quite obscure failures that are sure to drive
1245casual users crazy. Even experienced users will get confused :-). Upon
1246reflection, I'd say leave libperl.so in $archlib.
1247
94655993 1248=back
1249
1250=head2 Indentation style
2032ff04 1251
94655993 1252Over the years Perl has become a mishmash of
2032ff04 1253various indentation styles, but the original "Larry style" can
1254probably be restored with (GNU) indent somewhat like this:
1255
1256 indent -kr -nce -psl -sc
1257
55c0ed8c 1258A more ambitious solution would also specify a list of Perl specific
1259types with -TSV -TAV -THV .. -TMAGIC -TPerlIO ... but that list would
1260be quite ungainly. Also note that GNU indent also doesn't do aligning
1261of consecutive assignments, which would truly wreck the layout in
1262places like sv.c:Perl_sv_upgrade() or sv.c:Perl_clone_using().
1263Similarly nicely aligned &&s, ||s and ==s would not be respected.
2032ff04 1264
aa689395 1265=head1 Upload Your Work to CPAN
1266
1267You can upload your work to CPAN if you have a CPAN id. Check out
a93751fa 1268http://www.cpan.org/modules/04pause.html for information on
aa689395 1269_PAUSE_, the Perl Author's Upload Server.
1270
1271I typically upload both the patch file, e.g. F<perl5.004_08.pat.gz>
1272and the full tar file, e.g. F<perl5.004_08.tar.gz>.
1273
1274If you want your patch to appear in the F<src/5.0/unsupported>
1275directory on CPAN, send e-mail to the CPAN master librarian. (Check
a93751fa 1276out http://www.cpan.org/CPAN.html ).
aa689395 1277
1278=head1 Help Save the World
1279
1280You should definitely announce your patch on the perl5-porters list.
1281You should also consider announcing your patch on
1282comp.lang.perl.announce, though you should make it quite clear that a
1283subversion is not a production release, and be prepared to deal with
1284people who will not read your disclaimer.
1285
1286=head1 Todo
1287
1288Here, in no particular order, are some Configure and build-related
1289items that merit consideration. This list isn't exhaustive, it's just
1290what I came up with off the top of my head.
1291
e25f343d 1292=head2 Adding missing library functions to Perl
1293
1294The perl Configure script automatically determines which headers and
1295functions you have available on your system and arranges for them to be
1296included in the compilation and linking process. Occasionally, when porting
1297perl to an operating system for the first time, you may find that the
1298operating system is missing a key function. While perl may still build
1299without this function, no perl program will be able to reference the missing
1300function. You may be able to write the missing function yourself, or you
1301may be able to find the missing function in the distribution files for
1302another software package. In this case, you need to instruct the perl
1303configure-and-build process to use your function. Perform these steps.
1304
1305=over 3
1306
1307=item *
1308
2ecb232b 1309Code and test the function you wish to add. Test it carefully; you will
e25f343d 1310have a much easier time debugging your code independently than when it is a
1311part of perl.
1312
1313=item *
1314
1315Here is an implementation of the POSIX truncate function for an operating
1316system (VOS) that does not supply one, but which does supply the ftruncate()
1317function.
1318
1319 /* Beginning of modification history */
1320 /* Written 02-01-02 by Nick Ing-Simmons (nick@ing-simmons.net) */
1321 /* End of modification history */
1322
1323 /* VOS doesn't supply a truncate function, so we build one up
1324 from the available POSIX functions. */
1325
1326 #include <fcntl.h>
1327 #include <sys/types.h>
1328 #include <unistd.h>
1329
1330 int
1331 truncate(const char *path, off_t len)
1332 {
1333 int fd = open(path,O_WRONLY);
1334 int code = -1;
1335 if (fd >= 0) {
1336 code = ftruncate(fd,len);
1337 close(fd);
1338 }
1339 return code;
1340 }
1341
1342Place this file into a subdirectory that has the same name as the operating
1343system. This file is named perl/vos/vos.c
1344
1345=item *
1346
1347If your operating system has a hints file (in perl/hints/XXX.sh for an
1348operating system named XXX), then start with it. If your operating system
1349has no hints file, then create one. You can use a hints file for a similar
1350operating system, if one exists, as a template.
1351
1352=item *
1353
1354Add lines like the following to your hints file. The first line
1355(d_truncate="define") instructs Configure that the truncate() function
1356exists. The second line (archobjs="vos.o") instructs the makefiles that the
1357perl executable depends on the existence of a file named "vos.o". (Make
1358will automatically look for "vos.c" and compile it with the same options as
1359the perl source code). The final line ("test -h...") adds a symbolic link
1360to the top-level directory so that make can find vos.c. Of course, you
1361should use your own operating system name for the source file of extensions,
1362not "vos.c".
1363
1364 # VOS does not have truncate() but we supply one in vos.c
1365 d_truncate="define"
1366 archobjs="vos.o"
1367
1368 # Help gmake find vos.c
1369 test -h vos.c || ln -s vos/vos.c vos.c
1370
1371The hints file is a series of shell commands that are run in the top-level
1372directory (the "perl" directory). Thus, these commands are simply executed
1373by Configure at an appropriate place during its execution.
1374
1375=item *
1376
1377At this point, you can run the Configure script and rebuild perl. Carefully
1378test the newly-built perl to ensure that normal paths, and error paths,
1379behave as you expect.
1380
1381=back
1382
aa689395 1383=head2 Good ideas waiting for round tuits
1384
1385=over 4
1386
c4f23d77 1387=item Configure -Dsrc=/blah/blah
aa689395 1388
1389We should be able to emulate B<configure --srcdir>. Tom Tromey
1390tromey@creche.cygnus.com has submitted some patches to
c4f23d77 1391the dist-users mailing list along these lines. They have been folded
1392back into the main distribution, but various parts of the perl
1393Configure/build/install process still assume src='.'.
aa689395 1394
1395=item Hint file fixes
1396
1397Various hint files work around Configure problems. We ought to fix
1398Configure so that most of them aren't needed.
1399
1400=item Hint file information
1401
1402Some of the hint file information (particularly dynamic loading stuff)
1403ought to be fed back into the main metaconfig distribution.
1404
1405=back
1406
1407=head2 Probably good ideas waiting for round tuits
1408
1409=over 4
1410
1411=item GNU configure --options
1412
1413I've received sensible suggestions for --exec_prefix and other
1414GNU configure --options. It's not always obvious exactly what is
1415intended, but this merits investigation.
1416
1417=item make clean
1418
1419Currently, B<make clean> isn't all that useful, though
1420B<make realclean> and B<make distclean> are. This needs a bit of
1421thought and documentation before it gets cleaned up.
1422
1423=item Try gcc if cc fails
1424
1425Currently, we just give up.
1426
1427=item bypassing safe*alloc wrappers
1428
1429On some systems, it may be safe to call the system malloc directly
1430without going through the util.c safe* layers. (Such systems would
1431accept free(0), for example.) This might be a time-saver for systems
1432that already have a good malloc. (Recent Linux libc's apparently have
1433a nice malloc that is well-tuned for the system.)
1434
1435=back
1436
1437=head2 Vague possibilities
1438
1439=over 4
1440
aa689395 1441=item MacPerl
1442
3e3baf6d 1443Get some of the Macintosh stuff folded back into the main distribution.
aa689395 1444
1445=item gconvert replacement
1446
1447Maybe include a replacement function that doesn't lose data in rare
1448cases of coercion between string and numerical values.
1449
aa689395 1450=item Improve makedepend
1451
1452The current makedepend process is clunky and annoyingly slow, but it
1453works for most folks. Alas, it assumes that there is a filename
1454$firstmakefile that the B<make> command will try to use before it uses
1455F<Makefile>. Such may not be the case for all B<make> commands,
1456particularly those on non-Unix systems.
1457
1458Probably some variant of the BSD F<.depend> file will be useful.
1459We ought to check how other packages do this, if they do it at all.
1460We could probably pre-generate the dependencies (with the exception of
1461malloc.o, which could probably be determined at F<Makefile.SH>
1462extraction time.
1463
1464=item GNU Makefile standard targets
1465
1466GNU software generally has standardized Makefile targets. Unless we
1467have good reason to do otherwise, I see no reason not to support them.
1468
1469=item File locking
1470
1471Somehow, straighten out, document, and implement lockf(), flock(),
76ba0908 1472and/or fcntl() file locking. It's a mess. See $d_fcntl_can_lock
1473in recent config.sh files though.
aa689395 1474
1475=back
1476
4bb101f2 1477=head2 Copyright Issues
1478
1479The following is based on the consensus of a couple of IPR lawyers,
1480but it is of course not a legally binding statement, just a common
1481sense summary.
1482
1483=over 4
1484
1485=item *
1486
1487Tacking on copyright statements is unnecessary to begin with because
1488of the Berne convention. But assuming you want to go ahead...
1489
1490=item *
1491
1492The right form of a copyright statement is
1493
1494 Copyright (C) Year, Year, ... by Someone
1495
1496The (C) is not required everywhere but it doesn't hurt and in certain
1497jurisdictions it is required, so let's leave it in. (Yes, it's true
1498that in some jurisdictions the "(C)" is not legally binding, one should
1499use the true ringed-C. But we don't have that character available for
1500Perl's source code.)
1501
1502The years must be listed out separately. Year-Year is not correct.
1503Only the years when the piece has changed 'significantly' may be added.
1504
1505=item *
1506
1507One cannot give away one's copyright trivially. One can give one's
1508copyright away by using public domain, but even that requires a little
1509bit more than just saying 'this is in public domain'. (What it
1510exactly requires depends on your jurisdiction.) But barring public
1511domain, one cannot "transfer" one's copyright to another person or
1512entity. In the context of software, it means that contributors cannot
1513give away their copyright or "transfer" it to the "owner" of the software.
1514
1515Also remember that in many cases if you are employed by someone,
1516your work may be copyrighted to your employer, even when you are
1517contributing on your own time (this all depends on too many things
1518to list here). But the bottom line is that you definitely can't give
1519away a copyright you may not even have.
1520
1521What is possible, however, is that the software can simply state
1522
1523 Copyright (C) Year, Year, ... by Someone and others
1524
1525and then list the "others" somewhere in the distribution.
1526And this is exactly what Perl does. (The "somewhere" is
1527AUTHORS and the Changes* files.)
1528
1529=item *
1530
1531Split files, merged files, and generated files are problematic.
1532The rule of thumb: in split files, copy the copyright years of
1533the original file to all the new files; in merged files make
1534an union of the copyright years of all the old files; in generated
1535files propagate the copyright years of the generating file(s).
1536
1537=item *
1538
1539The files of Perl source code distribution do carry a lot of
1540copyrights, by various people. (There are many copyrights embedded in
1541perl.c, for example.) The most straightforward thing for pumpkings to
1542do is to simply update Larry's copyrights at the beginning of the
1543*.[hcy], x2p/*.[hcy], *.pl, and README files, and leave all other
1544copyrights alone. Doing more than that requires quite a bit of tracking.
1545
1546=back
1547
fb73857a 1548=head1 AUTHORS
aa689395 1549
36816da2 1550Original author: Andy Dougherty doughera@lafayette.edu .
fb73857a 1551Additions by Chip Salzenberg chip@perl.com and
1552Tim Bunce Tim.Bunce@ig.co.uk .
aa689395 1553
1554All opinions expressed herein are those of the authorZ<>(s).
1555
1556=head1 LAST MODIFIED
1557
449b893f 155827-04-2007 H.Merijn Brand
ff935051 1559$Id: pumpkin.pod,v 1.23 2000/01/13 19:45:13 doughera Released $