ExtUtils::MakeMaker 6.03 -> 6.06_05ish

[p5sagit/p5-mst-13.2.git] / lib / ExtUtils / PATCHING

This is a short set of guidelines for those patching
ExtUtils::MakeMaker.  Its not an iron-clad set of rules, but just
things which make life easier when reading and integrating a patch.

Lots of information can be found in makemaker.org.

MakerMaker is being maintained until something else can replace it.
Bugs will be fixed and compatibility improved, but I would like to
avoid new features.  If you want to add something to MakeMaker,
consider instead working on Module::Build, MakeMaker's heir apparent.


Patching details

- Please use unified diffs.  (diff -u)

- Patches against the latest development snapshot from makemaker.org are 
  preferred.  Patches against the latest CPAN version are ok, too.

- Post your patch to makemaker@perl.org.


Code formatting

- No literal tabs (except where necessary inside Makefile code, obviously).

- 4 character indentation.

- this_style is prefered instead of studlyCaps.

- Private subroutine names (ie. those used only in the same package
  they're declared in) should start with an underscore (_sekret_method).

- Protected subroutines (ie. ones intended to be used by other modules in
  ExtUtils::*) should be named normally (no leading underscore) but
  documented as protected (see Documentation below).

- Do not use indirect object syntax (ie. new Foo::Bar (@args))

- make variables use dollar signs like Perl scalars.  This causes problems
  when you have to mix them both in a string.  If you find yourself
  backwacking lots of dollar signs because you have one interpolated
  perl variable, like this:

    return <<'EOT'

subdirs ::
	\$(NOECHO)cd $subdir && \$(MAKE) -f \$(FIRST_MAKEFILE) all \$(PASTHRU)
EOT

  or are switching quoting contexts:

    return <<q{
subdirs ::
	$(NOECHO)cd }.$subdir.q{ && $(MAKE) -f $(FIRST_MAKEFILE) all $(PASTHRU)
};

  consider using sprintf instead.

    return sprintf <<'EOT', $subdir;

subdirs ::
	$(NOECHO)cd %s && $(MAKE) -f $(FIRST_MAKEFILE) all $(PASTHRU)
EOT


Refactoring and Cleanup

- MakeMaker is a mess.  We like patches which clean things up.


Backwards Compatibility

- MakeMaker must be backwards compatible to 5.5.3 (5.005_03).  Avoid any
  obvious 5.6-isms (threads, warnings.pm, Unicode, our, v1.2.3, attributes
  open my $fh, lvalue subroutines, any new core modules, etc...).

- MakeMaker should avoid having module dependencies.  Avoid using modules
  which didn't come with 5.5.3 and avoid using features from newer 
  versions.  Sometimes this is unavoidable.


Cross-Platform Compatibility

- MakeMaker must work on all architectures Perl works on (see perlport.pod)
  and with many different versions of make.  This means all Unixen 
  (including Cygwin and MacOS X), Windows (including DOS), MacOS Classic 
  and VMS.  

- Often when you patch ExtUtils::MM_Unix, similar patches must be done
  to the other MM_* modules.  If you can, please do this extra work
  otherwise I have to.  If you can't, that's ok.  We can help.

- If possible, please test your patch on two Very Different architectures.
  Unix, Windows, MacOS Classic and VMS being Very Different.  Note: Cygwin
  and OS X are Unixen for our purposes.

- If nothing else, at least try it on two different Unixen or Windows
  machines (ie. Linux and IRIX or WinNT and Win95).

- HP's TestDrive (www.testdrive.compaq.com) and SourceForge's
  compile farm (www.sourceforge.net) are good sources of testing
  machines of many different architectures and platforms.  Accounts are 
  free.

- If you find yourself writing "do_this if $^O eq 'That'" (ie. checks on
  the OS type) perhaps your code belongs in one of the non-Unix MM_*
  modules (ie. MM_Win32, MM_VMS, etc...).  If one does not exist, consider
  creating one.  Its ok to have an MM_* module with only one method.

- Some shells have very small buffers.  This means command lines must
  be as small as possible.  20K is the upper limit for Unixen, and 256
  for VMS.  Not sure what Windows and DOS are limited to, probably 1K.
  This limit *includes* any files passed into it.  Some modules (such as
  bioperl) generate enourmous commands because of their large number of
  files.  If your command is just too long, consider making it an
  ExtUtils::Command::MM function.

- Most shells quote differently.  If you need to put a perl one-liner
  in the Makefile, please use oneliner() to generate it.


Tests

- Tests would be nice, but I'm not going to pretend testing MakeMaker
  is easy.  If nothing else, let us know how you tested your patch by
  hand.


Documentation

- Documentation would be nice.

- If the new feature/method is private, please document it with POD
  wrapped in "=begin/end private" tags.  That way it will be documented,
  but won't be displayed (future versions of perldoc may have options
  to display).

    =begin private

    =item _foo_bar

       $mm->_foo_bar

    Blah blah blah

    =end private

    =cut

    sub _foo_bar {
       ...

- If you're overriding a method, document that its an override and
  *why* its being overridden.  Don't repeat the original documentation.