=head1 NAME
-Pumpkin - Notes on handling the Perl Patch Pumpkin
+Pumpkin - Notes on handling the Perl Patch Pumpkin And Porting Perl
=head1 SYNOPSIS
The Comprehensive Perl Archive Network (or CPAN) is the place to go.
There are many mirrors, but the easiest thing to use is probably
-http://www.perl.com/CPAN/README.html , which automatically points you to a
+L<http://www.cpan.org/README.html> , which automatically points you to a
mirror site "close" to you.
=head2 Perl5-porters mailing list
subscribe. The list is high volume, but generally has a
fairly low noise level.
-Subscribe by sending the message (in the body of your letter)
+To subscribe to perl5-porters, send an email to
- subscribe perl5-porters
-
-to perl5-porters-request@perl.org .
+ perl5-porters-subscribe@perl.org
Archives of the list are held at:
- http://www.rosat.mpe-garching.mpg.de/mailing-lists/perl-porters/
+ https://lists.perl.org/list/perl5-porters.html
=head1 How are Perl Releases Numbered?
-Perl version numbers are floating point numbers, such as 5.004.
-(Observations about the imprecision of floating point numbers for
-representing reality probably have more relevance than you might
-imagine :-) The major version number is 5 and the '004' is the
-patchlevel. (Questions such as whether or not '004' is really a minor
-version number can safely be ignored.:)
-
-The version number is available as the magic variable $],
-and can be used in comparisons, e.g.
+Beginning with v5.6.0, even versions will stand for maintenance releases
+and odd versions for development releases, i.e., v5.6.x for maintenance
+releases, and v5.7.x for development releases. Before v5.6.0, subversions
+_01 through _49 were reserved for bug-fix maintenance releases, and
+subversions _50 through _99 for unstable development versions.
- print "You've got an old perl\n" if $] < 5.002;
+For example, in v5.6.1, the revision number is 5, the version is 6,
+and 1 is the subversion.
-You can also require particular version (or later) with
+For compatibility with the older numbering scheme the composite floating
+point version number continues to be available as the magic variable $],
+and amounts to C<$revision + $version/1000 + $subversion/100000>. This
+can still be used in comparisons.
- use 5.002;
+ print "You've got an old perl\n" if $] < 5.005_03;
-At some point in the future, we may need to decide what to call the
-next big revision. In the .package file used by metaconfig to
-generate Configure, there are two variables that might be relevant:
-$baserev=5.0 and $package=perl5. At various times, I have suggested
-we might change them to $baserev=5.1 and $package=perl5.1 if want
-to signify a fairly major update. Or, we might want to jump to perl6.
-Let's worry about that problem when we get there.
+In addition, the version is also available as a string in $^V.
-=head2 Subversions
+ print "You've got a new perl\n" if $^V and $^V ge v5.6.0;
-In addition, there usually are sub-versions available. Sub-versions
-are numbered with sub-version numbers. For example, version 5.003_04
-is the 4'th developer version built on top of 5.003. It might include
-the _01, _02, and _03 changes, but it also might not. Sub-versions are
-allowed to be subversive. (But see the next section for recent
-changes.)
+You can also require particular version (or later) with:
-These sub-versions can also be used as floating point numbers, so
-you can do things such as
+ use 5.006;
- print "You've got an unstable perl\n" if $] == 5.00303;
+or using the new syntax available only from v5.6 onward:
-You can also require particular version (or later) with
+ use v5.6.0;
- use 5.003_03; # the "_" is optional
+At some point in the future, we may need to decide what to call the
+next big revision. In the .package file used by metaconfig to
+generate Configure, there are two variables that might be relevant:
+$baserev=5 and $package=perl5.
-Sub-versions produced by the members of perl5-porters are usually
+Perl releases produced by the members of perl5-porters are usually
available on CPAN in the F<src/5.0/maint> and F<src/5.0/devel>
directories.
=head2 Maintenance and Development Subversions
-Starting with version 5.004, subversions _01 through _49 is reserved
-for bug-fix maintenance releases, and subversions _50 through _99 for
-unstable development versions.
-
-The separate bug-fix track is being established to allow us an easy
-way to distribute important bug fixes without waiting for the
-developers to untangle all the other problems in the current
-developer's release. The first rule of maintenance work is "First, do
-no harm."
+The first rule of maintenance work is "First, do no harm."
Trial releases of bug-fix maintenance releases are announced on
perl5-porters. Trial releases use the new subversion number (to avoid
testers installing it over the previous release) and include a 'local
-patch' entry in patchlevel.h. The distribution file contains the
+patch' entry in F<patchlevel.h>. The distribution file contains the
string C<MAINT_TRIAL> to make clear that the file is not meant for
public consumption.
In general, the names of official distribution files for the public
-always match the regular expression
+always match the regular expression:
- ^perl5\.\d{3}(_[0-4]\d)?\.tar\.gz$
+ ^perl\d+\.(\d+)\.\d+(-MAINT_TRIAL_\d+)\.tar\.gz$
-Developer releases always match
+C<$1> in the pattern is always an even number for maintenance
+versions, and odd for developer releases.
- ^perl5\.\d{3}(_[5-9]\d)?\.tar\.gz$
-
-And the trial versions for a new maintainance release match
-
- ^perl5\.\d{3}(_[0-4]\d)-MAINT_TRIAL_\d+\.tar\.gz$
-
-In the past it has been observed that pumkings tend to invent new
+In the past it has been observed that pumpkings tend to invent new
naming conventions on the fly. If you are a pumpking, before you
invent a new name for any of the three types of perl distributions,
please inform the guys from the CPAN who are doing indexing and
provide the trees of symlinks and the like. They will have to know
I<in advance> what you decide.
-=head2 Why such a complicated scheme?
-
-Two reasons, really. At least.
-
-First, we need some way to identify and release collections of patches
-that are known to have new features that need testing and exploration. The
-subversion scheme does that nicely while fitting into the
-C<use 5.004;> mold.
-
-Second, since most of the folks who help maintain perl do so on a
-free-time voluntary basis, perl development does not proceed at a
-precise pace, though it always seems to be moving ahead quickly.
-We needed some way to pass around the "patch pumpkin" to allow
-different people chances to work on different aspects of the
-distribution without getting in each other's way. It wouldn't be
-constructive to have multiple people working on incompatible
-implementations of the same idea. Instead what was needed was
-some kind of "baton" or "token" to pass around so everyone knew
-whose turn was next.
-
=head2 Why is it called the patch pumpkin?
Chip Salzenberg gets credit for that, with a nod to his cow orker,
If feasible, try to keep filenames 8.3-compliant to humor those poor
souls that get joy from running Perl under such dire limitations.
+There's a script, F<check83.pl>, for keeping your nose 8.3-clean.
+In a similar vein, do not create files or directories which differ only
+in case (upper versus lower).
=head2 Seek consensus on major changes
=item source code
If you have many machine-specific #defines or #includes, consider
-creating an "osish.h" (os2ish.h, vmsish.h, and so on) and including
-that in perl.h. If you have several machine-specific files (function
+creating an "osish.h" (F<os2ish.h>, F<vmsish.h>, and so on) and including
+that in F<perl.h>. If you have several machine-specific files (function
emulations, function stubs, build utility wrappers) you may create a
separate subdirectory (djgpp, win32) and put the files in there.
Remember to update C<MANIFEST> when you add files.
-If your system support dynamic loading but none of the existing
+If your system supports dynamic loading but none of the existing
methods at F<ext/DynaLoader/dl_*.xs> work for you, you must write
a new one. Study the existing ones to see what kind of interface
you must supply.
line options and possibly existing config.sh and Policy.sh files from
previous Configure runs.
-The extension hints are written Perl (by the time they are used
+The extension hints are written in Perl (by the time they are used
miniperl has been built) and control the building of their respective
extensions. They can be used to for example manipulate compilation
and linking flags.
File::Copy to become aware of your native filesystem syntax and
peculiarities.
+Remember to have a $VERSION in the modules. You can use the
+F<Porting/checkVERSION.pl> script for checking this.
+
=item documentation
If your operating system comes from outside UNIX you almost certainly
A file called F<README.youros> at the top level that explains things
like how to install perl at this platform, where to get any possibly
required additional software, and for example what test suite errors
-to expect, is nice too.
+to expect, is nice too. Such files are in the process of being written
+in pod format and will eventually be renamed F<INSTALL.youros>.
You may also want to write a separate F<.pod> file for your operating
system to tell about existing mailing lists, os-specific modules,
=head2 Automated generation of derivative files
-The F<embed.h>, F<keywords.h>, F<opcode.h>, and F<perltoc.pod> files
+The F<embed.h>, F<keywords.h>, F<opcode.h>, F<regcharclass.h>,
+F<l1_char_class_tab.h>, and F<perltoc.pod> files
are all automatically generated by perl scripts. In general, don't
patch these directly; patch the data files instead.
-F<Configure> and F<config_h.SH> are also automatically generated by
-B<metaconfig>. In general, you should patch the metaconfig units
-instead of patching these files directly. However, very minor changes
-to F<Configure> may be made in between major sync-ups with the
-metaconfig units, which tends to be complicated operations. But be
-careful, this can quickly spiral out of control. Running metaconfig
-is not really hard.
-
Also F<Makefile> is automatically produced from F<Makefile.SH>.
In general, look out for all F<*.SH> files.
-Finally, the sample files in the F<Porting/> subdirectory are
-generated automatically by the script F<U/mksample> included
-with the metaconfig units. See L<"run metaconfig"> below for
-information on obtaining the metaconfig units.
+Finally, the sample files F<config.sh> and F<config_H> in the
+F<Porting/> subdirectory are generated by the script F<Porting/mksample>.
-=head1 How to Make a Distribution
+=head3 Files generated by metaconfig
-There really ought to be a 'make dist' target, but there isn't.
-The 'dist' suite of tools also contains a number of tools that I haven't
-learned how to use yet. Some of them may make this all a bit easier.
+F<Configure>, F<config_h.SH> and F<Porting/Glossary> are generated by
+B<metaconfig> (see below for more information on how to use this system)
+and direct changes to these files should in general not be pushed to blead.
-Here are the steps I go through to prepare a patch & distribution.
+The exceptions are:
-Lots of it could doubtless be automated but isn't. The Porting/makerel
-(make release) perl script does now help automate some parts of it.
+=over 4
-=head2 Announce your intentions
+=item *
-First, you should volunteer out loud to take the patch pumpkin. It's
-generally counter-productive to have multiple people working in secret
-on the same thing.
+security fixes
-At the same time, announce what you plan to do with the patch pumpkin,
-to allow folks a chance to object or suggest alternatives, or do it for
-you. Naturally, the patch pumpkin holder ought to incorporate various
-bug fixes and documentation improvements that are posted while he or
-she has the pumpkin, but there might also be larger issues at stake.
+=item *
-One of the precepts of the subversion idea is that we shouldn't give
-the patch pumpkin to anyone unless we have some idea what he or she
-is going to do with it.
+changes pre-approved by the metaconfig maintainers
-=head2 refresh pod/perltoc.pod
+=back
-Presumably, you have done a full C<make> in your working source
-directory. Before you C<make spotless> (if you do), and if you have
-changed any documentation in any module or pod file, change to the
-F<pod> directory and run C<make toc>.
+Such changes should also be notified to the metaconfig maintainers.
-=head2 run installhtml to check the validity of the pod files
+Alternatively, do consider if the F<*ish.h> files or the hint files might
+be a better place for your changes.
-=head2 update patchlevel.h
+=head1 Working with metaconfig
-Don't be shy about using the subversion number, even for a relatively
-modest patch. We've never even come close to using all 99 subversions,
-and it's better to have a distinctive number for your patch. If you
-need feedback on your patch, go ahead and issue it and promise to
-incorporate that feedback quickly (e.g. within 1 week) and send out a
-second patch.
+Information about how to use metaconfig can be found in the F<README>
+and F<README_U> files in the metaconfig repository containing Perl's
+metaconfig units:
-=head2 run metaconfig
+ # anonymous clone
+ git clone https://github.com/perl5-metaconfig/metaconfig.git
+ # or using a registered github.com identity with ssh
+ git clone github.com:perl5-metaconfig/metaconfig metaconfig
-If you need to make changes to Configure or config_h.SH, it may be best to
-change the appropriate metaconfig units instead, and regenerate Configure.
+Since metaconfig is hard to change, running correction scripts after
+this generation is sometimes needed. Configure gained complexity over
+time, and the order in which config_h.SH is generated can cause havoc
+when compiling perl. Therefor, you need to run Porting/config_h.pl
+after that generation. All that and more is described in the README
+files that come with the metaunits.
- metaconfig -m
+=head1 How to Make a Distribution
-will regenerate Configure and config_h.SH. Much more information
-on obtaining and running metaconfig is in the F<U/README> file
-that comes with Perl's metaconfig units. Perl's metaconfig units
-should be available on CPAN. A set of units that will work with
-perl5.005 is in the file F<mc_units-5.005_00-01.tar.gz> under
-http://www.perl.com/CPAN/authors/id/ANDYD/ . The mc_units tar file
-should be unpacked in your main perl source directory. Note: those
-units were for use with 5.005. There may have been changes since then.
-Check for later versions or contact perl5-porters@perl.org to obtain a
-pointer to the current version.
+This section has now been expanded and moved into its own file,
+F<Porting/release_managers_guide.pod>.
-Alternatively, do consider if the F<*ish.h> files might be a better
-place for your changes.
+I've kept some of the subsections here for now, as they don't directly
+relate to building a release any more, but still contain what might be
+useful information - DAPM 7/2009.
=head2 MANIFEST
-Make sure the MANIFEST is up-to-date. You can use dist's B<manicheck>
-program for this. You can also use
-
- perl -w -MExtUtils::Manifest=fullcheck -e fullcheck
-
-Both commands will also list extra files in the directory that are not
-listed in MANIFEST.
-
-The MANIFEST is normally sorted.
-
If you are using metaconfig to regenerate Configure, then you should note
that metaconfig actually uses MANIFEST.new, so you want to be sure
MANIFEST.new is up-to-date too. I haven't found the MANIFEST/MANIFEST.new
distinction particularly useful, but that's probably because I still haven't
learned how to use the full suite of tools in the dist distribution.
-=head2 Check permissions
-
-All the tests in the t/ directory ought to be executable. The
-main makefile used to do a 'chmod t/*/*.t', but that resulted in
-a self-modifying distribution--something some users would strongly
-prefer to avoid. The F<t/TEST> script will check for this
-and do the chmod if needed, but the tests still ought to be
-executable.
-
-In all, the following files should probably be executable:
-
- Configure
- configpm
- configure.gnu
- embed.pl
- installperl
- installman
- keywords.pl
- myconfig
- opcode.pl
- perly.fixer
- t/TEST
- t/*/*.t
- *.SH
- vms/ext/Stdio/test.pl
- vms/ext/filespec.t
- x2p/*.SH
-
-Other things ought to be readable, at least :-).
-
-Probably, the permissions for the files could be encoded in MANIFEST
-somehow, but I'm reluctant to change MANIFEST itself because that
-could break old scripts that use MANIFEST.
-
-I seem to recall that some SVR3 systems kept some sort of file that listed
-permissions for system files; something like that might be appropriate.
=head2 Run Configure
sometimes get scrambled around, and the changes in config_H can
sometimes be very hard to follow. config.sh, on the other hand, can
safely be sorted, so it's easy to track (typically very small) changes
-to config.sh and then propoagate them to a canned 'config.h' by any
+to config.sh and then propagate them to a canned 'config.h' by any
number of means, including a perl script in win32/ or carrying
-config.sh and config_h.SH to a Unix system and running sh
-config_h.SH.)
+F<config.sh> and F<config_h.SH> to a Unix system and running sh
+config_h.SH.) Vms uses F<configure.com> to generate its own F<config.sh>
+and F<config.h>. If you want to add a new variable to F<config.sh> check
+with vms folk how to add it to configure.com too.
XXX]
-The Porting/config.sh and Porting/config_H files are provided to
+The F<Porting/config.sh> and F<Porting/config_H> files are provided to
help those folks who can't run Configure. It is important to keep
-them up-to-date. If you have changed config_h.SH, those changes must
+them up-to-date. If you have changed F<config_h.SH>, those changes must
be reflected in config_H as well. (The name config_H was chosen to
distinguish the file from config.h even on case-insensitive file systems.)
Simply edit the existing config_H file; keep the first few explanatory
lines and then copy your new config.h below.
-It may also be necessary to update win32/config.?c, vms/config.vms and
-plan9/config.plan9, though you should be quite careful in doing so if
+It may also be necessary to update win32/config.?c, and
+F<plan9/config.plan9>, though you should be quite careful in doing so if
you are not familiar with those systems. You might want to issue your
patch with a promise to quickly issue a follow-up that handles those
directories.
-=head2 make run_byacc
+=head2 make regen_perly
-If you have byacc-1.8.2 (available from CPAN), and if there have been
-changes to F<perly.y>, you can regenerate the F<perly.c> file. The
-run_byacc makefile target does this by running byacc and then applying
-some patches so that byacc dynamically allocates space, rather than
-having fixed limits. This patch is handled by the F<perly.fixer>
-script. Depending on the nature of the changes to F<perly.y>, you may
-or may not have to hand-edit the patch to apply correctly. If you do,
-you should include the edited patch in the new distribution. If you
-have byacc-1.9, the patch won't apply cleanly. Changes to the printf
-output statements mean the patch won't apply cleanly. Long ago I
-started to fix F<perly.fixer> to detect this, but I never completed the
-task.
+If F<perly.y> has been edited, it is necessary to run this target to rebuild
+F<perly.h>, F<perly.act> and F<perly.tab>. In fact this target just runs the Perl
+script F<regen_perly.pl>. Note that F<perly.c> is I<not> rebuilt; this is just a
+plain static file now.
-If C<perly.c> changes, make sure you run C<perl vms/vms_yfix.pl> to
-update the corresponding VMS files. See L<VMS-specific updates>.
+This target relies on you having Bison installed on your system. Running
+the target will tell you if you haven't got the right version, and if so,
+where to get the right one. Or if you prefer, you could hack
+F<regen_perly.pl> to work with your version of Bison. The important things
+are that the regexes can still extract out the right chunks of the Bison
+output into F<perly.act> and F<perly.tab>, and that the contents of those two
+files, plus F<perly.h>, are functionally equivalent to those produced by the
+supported version of Bison.
-Some additional notes from Larry on this:
+Note that in the old days, you had to do C<make run_byacc> instead.
-Don't forget to regenerate perly_c.diff.
+=head2 make regen_all
- byacc -d perly.y
- mv y.tab.c perly.c
- patch perly.c <perly_c.diff
- # manually apply any failed hunks
- diff -c2 perly.c.orig perly.c >perly_c.diff
-
-One chunk of lines that often fails begins with
-
- #line 29 "perly.y"
-
-and ends one line before
-
- #define YYERRCODE 256
-
-This only happens when you add or remove a token type. I suppose this
-could be automated, but it doesn't happen very often nowadays.
-
-Larry
+This target takes care of the regen_headers target.
+(It used to also call the regen_pods target, but that has been eliminated.)
=head2 make regen_headers
than answering all the questions and complaints about the failing
command.
-=head2 global.sym, interp.sym and perlio.sym
+=head2 globvar.sym, and perlio.sym
Make sure these files are up-to-date. Read the comments in these
-files and in perl_exp.SH to see what to do.
+files and in F<perl_exp.SH> to see what to do.
=head2 Binary compatibility
-If you do change F<global.sym> or F<interp.sym>, think carefully about
+If you do change F<embed.fnc> think carefully about
what you are doing. To the extent reasonable, we'd like to maintain
-souce and binary compatibility with older releases of perl. That way,
+source and binary compatibility with older releases of perl. That way,
extensions built under one version of perl will continue to work with
new versions of perl.
backwards-compatibility stubs. There's a lot of XS code out there.
Let's not force people to keep changing it.
-=head2 Changes
+=head2 PPPort
-Be sure to update the F<Changes> file. Try to include both an overall
-summary as well as detailed descriptions of the changes. Your
-audience will include other developers and users, so describe
-user-visible changes (if any) in terms they will understand, not in
-code like "initialize foo variable in bar function".
+F<dist/Devel-PPPort/PPPort.pm> needs to be synchronized to include all
+new macros added to .h files (normally F<perl.h> and F<XSUB.h>, but others
+as well). Since chances are that when a new macro is added the
+committer will forget to update F<PPPort.pm>, it's the best to diff for
+changes in .h files when making a new release and making sure that
+F<PPPort.pm> contains them all.
+
+The pumpking can delegate the synchronization responsibility to anybody
+else, but the release process is the only place where we can make sure
+that no new macros fell through the cracks.
-There are differing opinions on whether the detailed descriptions
-ought to go in the Changes file or whether they ought to be available
-separately in the patch file (or both). There is no disagreement that
-detailed descriptions ought to be easily available somewhere.
=head2 Todo
-The F<Todo> file contains a roughly-catgorized unordered list of
-aspects of Perl that could use enhancement, features that could be
-added, areas that could be cleaned up, and so on. During your term as
-pumpkin-holder, you will probably address some of these issues, and
-perhaps identify others which, while you decide not to address them
-this time around, may be tackled in the future. Update the file
-reflect the situation as it stands when you hand over the pumpkin.
+The F<Porting/todo.pod> file contains a roughly-categorized unordered
+list of aspects of Perl that could use enhancement, features that could
+be added, areas that could be cleaned up, and so on. During your term
+as pumpkin-holder, you will probably address some of these issues, and
+perhaps identify others which, while you decide not to address them this
+time around, may be tackled in the future. Update the file to reflect
+the situation as it stands when you hand over the pumpkin.
You might like, early in your pumpkin-holding career, to see if you
-can find champions for partiticular issues on the to-do list: an issue
+can find champions for particular issues on the to-do list: an issue
owned is an issue more likely to be resolved.
-There are also some more porting-specific L<Todo> items later in this
+There are also some more porting-specific L</Todo> items later in this
file.
=head2 OS/2-specific updates
=head2 VMS-specific updates
-If you have changed F<perly.y> or F<perly.c>, then you most probably want
-to update F<vms/perly_{h,c}.vms> by running C<perl vms/vms_yfix.pl>.
-
-The Perl version number appears in several places under F<vms>.
-It is courteous to update these versions. For example, if you are
-making 5.004_42, replace "5.00441" with "5.00442".
+The Perl revision number appears as "perl5" in F<configure.com>.
+It is courteous to update that if necessary.
-=head2 Making the new distribution
-
-Suppose, for example, that you want to make version 5.004_08. Then you can
-do something like the following
-
- mkdir ../perl5.004_08
- awk '{print $1}' MANIFEST | cpio -pdm ../perl5.004_08
- cd ../
- tar cf perl5.004_08.tar perl5.004_08
- gzip --best perl5.004_08.tar
-
-These steps, with extra checks, are automated by the Porting/makerel
-script.
=head2 Making a new patch
I find the F<makepatch> utility quite handy for making patches.
You can obtain it from any CPAN archive under
-http://www.perl.com/CPAN/authors/Johan_Vromans/ . There are a couple
+L<https://www.cpan.org/authors/id/J/JV/JV/>. There are a couple
of differences between my version and the standard one. I have mine do
a
You can also hand-tweak your config.h to try out different #ifdef
branches.
-=head1 Common Gotcha's
+=head2 Other tests
=over 4
-=item #elif
+=item gcc -ansi -pedantic
-The '#elif' preprocessor directive is not understood on all systems.
-Specifically, I know that Pyramids don't understand it. Thus instead of the
-simple
+Configure -Dgccansipedantic [ -Dcc=gcc ] will enable (via the cflags script,
+not $Config{ccflags}) the gcc strict ANSI C flags -ansi and -pedantic for
+the compilation of the core files on platforms where it knows it can
+do so (like Linux, see cflags.SH for the full list), and on some
+platforms only one (Solaris can do only -pedantic, not -ansi).
+The flag -DPERL_GCC_PEDANTIC also gets added, since gcc does not add
+any internal cpp flag to signify that -pedantic is being used, as it
+does for -ansi (__STRICT_ANSI__).
- #if defined(I_FOO)
- # include <foo.h>
- #elif defined(I_BAR)
- # include <bar.h>
- #else
- # include <fubar.h>
- #endif
+Note that the -ansi and -pedantic are enabled only for version 3 (and
+later) of gcc, since even gcc version 2.95.4 finds lots of seemingly
+false "value computed not used" errors from Perl.
-You have to do the more Byzantine
+The -ansi and -pedantic are useful in catching at least the following
+nonportable practices:
- #if defined(I_FOO)
- # include <foo.h>
- #else
- # if defined(I_BAR)
- # include <bar.h>
- # else
- # include <fubar.h>
- # endif
- #endif
+=over 4
+
+=item *
+
+gcc-specific extensions
+
+=item *
+
+lvalue casts
+
+=item *
+
+// C++ comments
+
+=item *
+
+enum trailing commas
+
+=back
+
+The -Dgccansipedantic should be used only when cleaning up the code,
+not for production builds, since otherwise gcc cannot inline certain
+things.
+
+=back
-Incidentally, whitespace between the leading '#' and the preprocessor
-command is not guaranteed, but is very portable and you may use it freely.
-I think it makes things a bit more readable, especially once things get
-rather deeply nested. I also think that things should almost never get
-too deeply nested, so it ought to be a moot point :-)
+=head1 Common Gotchas
+
+=over 4
=item Probably Prefer POSIX
For dynamic loading to work on AIX (and VMS) we need to provide a list
of symbols to be exported. This is done by the script F<perl_exp.SH>,
-which reads F<
global.sym> and F<interp.sym>. Thus, the C<pause>
-symbol would have to be added to F<global.sym> So far, so good.
+which reads F<
embed.fnc>. Thus, the C<pause>
+symbol would have to be added to F<embed.fnc> So far, so good.
On the other hand, one of the goals of Perl5 is to make it easy to
either extend or embed perl and link it with other libraries. This
That is, we don't want perl's global variables to conflict with
those in the other application library. Although this work is still
in progress, the way it is currently done is via the F<embed.h> file.
-This file is built from the F<global.sym> and F<interp.sym> files,
+This file is built from the F<embed.fnc> file,
since those files already list the globally visible symbols. If we
-had added C<pause> to global.sym, then F<embed.h> would contain the
+had added C<pause> to F<embed.fnc>, then F<embed.h> would contain the
line
#define pause Perl_pause
implemented in 5.003_05 isn't optimal, but here's what was done:
#ifdef HAS_CHSIZE
- # ifdef my_chsize /* Probably #defined to Perl_my_chsize in embed.h */
- # undef my_chsize
+ # ifdef my_chsize /* Probably #defined to Perl_my_chsize */
+ # undef my_chsize /* in embed.h */
# endif
# define my_chsize chsize
#endif
My explanatory comment in patch 5.003_05 said:
- Undef and then re-define my_chsize from Perl_my_chsize to
- just plain chsize if this system HAS_CHSIZE. This probably only
- applies to SCO. This shows the perils of having internal
- functions with the same name as external library functions :-).
+ Undef and then re-define my_chsize from Perl_my_chsize to
+ just plain chsize if this system HAS_CHSIZE. This probably only
+ applies to SCO. This shows the perils of having internal
+ functions with the same name as external library functions :-).
-Now, we can safely put C<my_chsize> in F<global.sym>, export it, and
+Now, we can safely put C<my_chsize> in C<embed.fnc>, export it, and
hide it with F<embed.h>.
To be consistent with what I did for C<pause>, I probably should have
#endif
Alternatively, we could just always use C<chsize> everywhere and move
-C<chsize> from F<
global.sym> to the end of F<perl_exp.SH>. That would
+C<chsize> from F<
embed.fnc> to the end of F<perl_exp.SH>. That would
probably be fine as long as our C<chsize> function agreed with all the
C<chsize> function prototypes in the various systems we'll be using.
As long as the prototypes in actual use don't vary that much, this is
=item Metaconfig worked for me
-My system at the time was Interactive 2.2, a SVR3.2/386 derivative that
+My system at the time was Interactive 2.2, an SVR3.2/386 derivative that
also had some POSIX support. Metaconfig-generated Configure scripts
worked fine for me on that system. On the other hand, autoconf-generated
scripts usually didn't. (They did come quite close, though, in some
=back
-=head2 @INC search order
-
-By default, the list of perl library directories in @INC is the
-following:
-
- $archlib
- $privlib
- $sitearch
- $sitelib
-
-Specifically, on my Solaris/x86 system, I run
-B<sh Configure -Dprefix=/opt/perl> and I have the following
-directories:
-
- /opt/perl/lib/i86pc-solaris/5.00307
- /opt/perl/lib
- /opt/perl/lib/site_perl/i86pc-solaris
- /opt/perl/lib/site_perl
-
-That is, perl's directories come first, followed by the site-specific
-directories.
-
-The site libraries come second to support the usage of extensions
-across perl versions. Read the relevant section in F<INSTALL> for
-more information. If we ever make $sitearch version-specific, this
-topic could be revisited.
-
=head2 Why isn't there a directory to override Perl's library?
Mainly because no one's gotten around to making one. Note that
a mail message from Larry:
The main intent of APPLLIB_EXP is for folks who want to send out a
- version of Perl embedded in their product. They would set the symbol
- to be the name of the library containing the files needed to run or to
- support their particular application. This works at the "override"
- level to make sure they get their own versions of any library code that
- they absolutely must have configuration control over.
+ version of Perl embedded in their product. They would set the
+ symbol to be the name of the library containing the files needed
+ to run or to support their particular application. This works at
+ the "override" level to make sure they get their own versions of
+ any library code that they absolutely must have configuration
+ control over.
As such, I don't see any conflict with a sysadmin using it for a
- override-ish sort of thing, when installing a generic Perl. It should
- probably have been named something to do with overriding though. Since
- it's undocumented we could still change it... :-)
+ override-ish sort of thing, when installing a generic Perl. It
+ should probably have been named something to do with overriding
+ though. Since it's undocumented we could still change it... :-)
+
+Given that it's already there, you can use it to override distribution modules.
+One way to do that is to add
-Given that it's already there, you can use it to override
-distribution modules. If you do
+ ccflags="$ccflags -DAPPLLIB_EXP=\"/my/override\""
- sh Configure -Dccflags='-DAPPLLIB_EXP=/my/override'
+to your config.over file. (You have to be particularly careful to get the
+double quotes in. APPLLIB_EXP must be a valid C string. It might
+actually be easier to just #define it yourself in perl.c.)
-then perl.c will put /my/override ahead of ARCHLIB and PRIVLIB.
+Then perl.c will put /my/override ahead of ARCHLIB and PRIVLIB. Perl will
+also search architecture-specific and version-specific subdirectories of
+APPLLIB_EXP.
=head2 Shared libperl.so location
perl5.004_04, ld.so might try to load libperl.so.4.5, since it has
the right "major version" number. If this works at all, it almost
certainly defeats the reason for keeping perl5.004_04 around. Worse,
-with development subversions, you certaily can't guarantee that
+with development subversions, you certainly can't guarantee that
libperl.so.4.4 and libperl.so.4.55 will be compatible.
Anyway, all this leads to quite obscure failures that are sure to drive
=back
+=head2 Indentation style
+
+Over the years Perl has become a mishmash of
+various indentation styles, but the original "Larry style" can
+probably be restored with (GNU) indent somewhat like this:
+
+ indent -kr -nce -psl -sc
+
+A more ambitious solution would also specify a list of Perl specific
+types with -TSV -TAV -THV .. -TMAGIC -TPerlIO ... but that list would
+be quite ungainly. Also note that GNU indent also doesn't do aligning
+of consecutive assignments, which would truly wreck the layout in
+places like sv.c:Perl_sv_upgrade() or sv.c:Perl_clone_using().
+Similarly nicely aligned &&s, ||s and ==s would not be respected.
+
=head1 Upload Your Work to CPAN
You can upload your work to CPAN if you have a CPAN id. Check out
-http://www.perl.com/CPAN/modules/04pause.html for information on
+L<http://www.cpan.org/modules/04pause.html> for information on
_PAUSE_, the Perl Author's Upload Server.
I typically upload both the patch file, e.g. F<perl5.004_08.pat.gz>
If you want your patch to appear in the F<src/5.0/unsupported>
directory on CPAN, send e-mail to the CPAN master librarian. (Check
-out http://www.perl.com/CPAN/CPAN.html ).
+out L<http://www.cpan.org/CPAN.html> ).
=head1 Help Save the World
You should definitely announce your patch on the perl5-porters list.
-You should also consider announcing your patch on
-comp.lang.perl.announce, though you should make it quite clear that a
-subversion is not a production release, and be prepared to deal with
-people who will not read your disclaimer.
=head1 Todo
items that merit consideration. This list isn't exhaustive, it's just
what I came up with off the top of my head.
-=head2 Good ideas waiting for round tuits
+=head2 Adding missing library functions to Perl
-=over 4
+The perl Configure script automatically determines which headers and
+functions you have available on your system and arranges for them to be
+included in the compilation and linking process. Occasionally, when porting
+perl to an operating system for the first time, you may find that the
+operating system is missing a key function. While perl may still build
+without this function, no perl program will be able to reference the missing
+function. You may be able to write the missing function yourself, or you
+may be able to find the missing function in the distribution files for
+another software package. In this case, you need to instruct the perl
+configure-and-build process to use your function. Perform these steps.
+
+=over 3
+
+=item *
+
+Code and test the function you wish to add. Test it carefully; you will
+have a much easier time debugging your code independently than when it is a
+part of perl.
+
+=item *
+
+Here is an implementation of the POSIX truncate function for an operating
+system (VOS) that does not supply one, but which does supply the ftruncate()
+function.
+
+ /* Beginning of modification history */
+ /* Written 02-01-02 by Nick Ing-Simmons (nick@ing-simmons.net) */
+ /* End of modification history */
+
+ /* VOS doesn't supply a truncate function, so we build one up
+ from the available POSIX functions. */
+
+ #include <fcntl.h>
+ #include <sys/types.h>
+ #include <unistd.h>
+
+ int
+ truncate(const char *path, off_t len)
+ {
+ int fd = open(path,O_WRONLY);
+ int code = -1;
+ if (fd >= 0) {
+ code = ftruncate(fd,len);
+ close(fd);
+ }
+ return code;
+ }
+
+Place this file into a subdirectory that has the same name as the operating
+system. This file is named perl/vos/vos.c
+
+=item *
-=item installprefix
+If your operating system has a hints file (in perl/hints/XXX.sh for an
+operating system named XXX), then start with it. If your operating system
+has no hints file, then create one. You can use a hints file for a similar
+operating system, if one exists, as a template.
-I think we ought to support
+=item *
- Configure -Dinstallprefix=/blah/blah
+Add lines like the following to your hints file. The first line
+(d_truncate="define") instructs Configure that the truncate() function
+exists. The second line (archobjs="vos.o") instructs the makefiles that the
+perl executable depends on the existence of a file named "vos.o". (Make
+will automatically look for "vos.c" and compile it with the same options as
+the perl source code). The final line ("test -h...") adds a symbolic link
+to the top-level directory so that make can find vos.c. Of course, you
+should use your own operating system name for the source file of extensions,
+not "vos.c".
-Currently, we support B<-Dprefix=/blah/blah>, but the changing the install
-location has to be handled by something like the F<config.over> trick
-described in F<INSTALL>. AFS users also are treated specially.
-We should probably duplicate the metaconfig prefix stuff for an
-install prefix.
+ # VOS does not have truncate() but we supply one in vos.c
+ d_truncate="define"
+ archobjs="vos.o"
+
+ # Help gmake find vos.c
+ test -h vos.c || ln -s vos/vos.c vos.c
+
+The hints file is a series of shell commands that are run in the top-level
+directory (the "perl" directory). Thus, these commands are simply executed
+by Configure at an appropriate place during its execution.
+
+=item *
+
+At this point, you can run the Configure script and rebuild perl. Carefully
+test the newly-built perl to ensure that normal paths, and error paths,
+behave as you expect.
+
+=back
+
+=head2 Good ideas waiting for round tuits
+
+=over 4
=item Configure -Dsrc=/blah/blah
back into the main distribution, but various parts of the perl
Configure/build/install process still assume src='.'.
-=item Directory for vendor-supplied modules?
-
-If a vendor supplies perl, but wants to leave $siteperl and $sitearch
-for the local user to use, where should the vendor put vendor-supplied
-modules (such as Tk.so?) If the vendor puts them in $archlib, then
-they need to be updated each time the perl version is updated.
-Perhaps we need a set of libries $vendorperl and $vendorarch that
-track $apiversion (like the $sitexxx directories do) rather than
-just $version (like the main perl directory).
-
=item Hint file fixes
Various hint files work around Configure problems. We ought to fix
Some of the hint file information (particularly dynamic loading stuff)
ought to be fed back into the main metaconfig distribution.
-=item Catch GNU Libc "Stub" functions
-
-Some functions (such as lchown()) are present in libc, but are
-unimplmented. That is, they always fail and set errno=ENOSYS.
-
-Thomas Bushnell provided the following sample code and the explanation
-that follows:
-
- /* System header to define __stub macros and hopefully few prototypes,
- which can conflict with char FOO(); below. */
- #include <assert.h>
- /* Override any gcc2 internal prototype to avoid an error. */
- /* We use char because int might match the return type of a gcc2
- builtin and then its argument prototype would still apply. */
- char FOO();
-
- int main() {
-
- /* The GNU C library defines this for functions which it implements
- to always fail with ENOSYS. Some functions are actually named
- something starting with __ and the normal name is an alias. */
- #if defined (__stub_FOO) || defined (__stub___FOO)
- choke me
- #else
- FOO();
- #endif
-
- ; return 0; }
-
-The choice of <assert.h> is essentially arbitrary. The GNU libc
-macros are found in <gnu/stubs.h>. You can include that file instead
-of <assert.h> (which itself includes <gnu/stubs.h>) if you test for
-its existence first. <assert.h> is assumed to exist on every system,
-which is why it's used here. Any GNU libc header file will include
-the stubs macros. If either __stub_NAME or __stub___NAME is defined,
-then the function doesn't actually exist. Tests using <assert.h> work
-on every system around.
-
-The declaration of FOO is there to override builtin prototypes for
-ANSI C functions.
-
=back
=head2 Probably good ideas waiting for round tuits
GNU configure --options. It's not always obvious exactly what is
intended, but this merits investigation.
-=item make clean
-
-Currently, B<make clean> isn't all that useful, though
-B<make realclean> and B<make distclean> are. This needs a bit of
-thought and documentation before it gets cleaned up.
-
=item Try gcc if cc fails
Currently, we just give up.
=over 4
-=item MacPerl
-
-Get some of the Macintosh stuff folded back into the main distribution.
-
=item gconvert replacement
Maybe include a replacement function that doesn't lose data in rare
=item File locking
Somehow, straighten out, document, and implement lockf(), flock(),
-and/or fcntl() file locking. It's a mess.
+and/or fcntl() file locking. It's a mess. See $d_fcntl_can_lock
+in recent config.sh files though.
+
+=back
+
+=head2 Copyright Issues
+
+The following is based on the consensus of a couple of IPR lawyers,
+but it is of course not a legally binding statement, just a common
+sense summary.
+
+=over 4
+
+=item *
+
+Tacking on copyright statements is unnecessary to begin with because
+of the Berne convention. But assuming you want to go ahead...
+
+=item *
+
+The right form of a copyright statement is
+
+ Copyright (C) Year, Year, ... by Someone
+
+The (C) is not required everywhere but it doesn't hurt and in certain
+jurisdictions it is required, so let's leave it in. (Yes, it's true
+that in some jurisdictions the "(C)" is not legally binding, one should
+use the true ringed-C. But we don't have that character available for
+Perl's source code.)
+
+The years must be listed out separately. Year-Year is not correct.
+Only the years when the piece has changed 'significantly' may be added.
+
+=item *
+
+One cannot give away one's copyright trivially. One can give one's
+copyright away by using public domain, but even that requires a little
+bit more than just saying 'this is in public domain'. (What it
+exactly requires depends on your jurisdiction.) But barring public
+domain, one cannot "transfer" one's copyright to another person or
+entity. In the context of software, it means that contributors cannot
+give away their copyright or "transfer" it to the "owner" of the software.
+
+Also remember that in many cases if you are employed by someone,
+your work may be copyrighted to your employer, even when you are
+contributing on your own time (this all depends on too many things
+to list here). But the bottom line is that you definitely can't give
+away a copyright you may not even have.
+
+What is possible, however, is that the software can simply state
+
+ Copyright (C) Year, Year, ... by Someone and others
+
+and then list the "others" somewhere in the distribution.
+And this is exactly what Perl does. (The "somewhere" is
+AUTHORS and the Changes* files.)
+
+=item *
+
+Split files, merged files, and generated files are problematic.
+The rule of thumb: in split files, copy the copyright years of
+the original file to all the new files; in merged files make
+an union of the copyright years of all the old files; in generated
+files propagate the copyright years of the generating file(s).
+
+=item *
+
+The files of Perl source code distribution do carry a lot of
+copyrights, by various people. (There are many copyrights embedded in
+perl.c, for example.) The most straightforward thing for pumpkings to
+do is to simply update Larry's copyrights at the beginning of the
+*.[hcy], *.pl, and README files, and leave all other
+copyrights alone. Doing more than that requires quite a bit of tracking.
=back
=head1 AUTHORS
-Original author: Andy Dougherty doughera@lafcol.lafayette.edu .
-Additions by Chip Salzenberg chip@perl.com and
-Tim Bunce Tim.Bunce@ig.co.uk .
+Original author: Andy Dougherty doughera@lafayette.edu .
+Additions by Chip Salzenberg chip@perl.com, Tim Bunce and the perl5
+development team.
All opinions expressed herein are those of the authorZ<>(s).
=head1 LAST MODIFIED
-$Id: pumpkin.pod,v 1.22 1998/07/22 16:33:55 doughera Released $
+2017-10-13 Dominic Hargreaves
https://perl5.git.perl.org / perl5.git / blobdiff