"The easy way is always mined.
The important things are always simple.
The simple things are always hard."
-- Some of Murphy's Laws of Combat
This is a short set of guidelines for those contributing
ExtUtils::MakeMaker. Its not an iron-clad set of rules, but just
things which make life easier when reading and integrating a patch.
Reporting bugs
- Often the only information we have for fixing a bug is contained in your
report. So...
- Please report your bugs via http://rt.cpan.org or
https://github.com/Perl-Toolchain-Gang/ExtUtils-MakeMaker/issues or
by mailing to makemaker@perl.org.
RT or GitHub are preferred.
- Please report your bug immediately upon encountering it. Do not wait
until you have a patch to fix the bug. Patches are good, but not at
the expense of timely bug reports.
- Please be as verbose as possible. Include the complete output of
your 'make test' or even 'make test TEST_VERBOSE=1' and a copy of the
generated Makefile. Err on the side of verbosity. The more data we
have to work with, the faster we can diagnose the problem.
- If you find an undocumented feature, or if a feature has changed/been
added which causes a problem, report it. Do not assume it was done
deliberately. Even if it was done deliberately, we still want to hear
if it caused problems.
- If you're testing MakeMaker against a development version of Perl,
please also check it against the latest stable version. This makes it
easier to figure out if its MakeMaker or Perl at fault.
Pull Request
- If you wrote a patch already, please Pull Request on GitHub.
- Pull Request against the latest development snapshot from GitHub
repository are preferred.
- Pull Request against the latest CPAN version are ok, too.
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 5.6.0.
Avoid any obvious 5.8-isms.
- MakeMaker should avoid having module dependencies.
But if new code need depends the modules absolutely,
it will bundle the modules.
See Makefile.PL of ExtUtils::MakeMaker for detail.
Cross-Platform Compatibility
- MakeMaker must work on all architectures Perl works on (see perlport.pod).
This means all Unixen (including Cygwin and MacOS X), Windows, and VMS.
- Use the available macros rather than shell commands $(MV), $(CP),
$(TOUCH), etc...
- MakeMaker must work on many makes. GNU, BSD, Solaris, nmake, dmake, MMS
and MMK to name the most common. Keep your make code as simple as
possible.
- Avoid special make variables (even $@).
- Format targets as "target : dependency", the spacing is important.
- Use $(NOECHO) instead of @.
- Use - to tell make to ignore the exit code of a command. (Unfortunately,
some make variants don't honor an $(IGNORE) macro).
- Always put a space between $(NOECHO) and the command.
- Always put a space between - (ignore) and the command.
- Always put $(NOECHO) and - together, no space between them.
# Right
-$(NOECHO) command
$(NOECHO) command
- command
- 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 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 machines
(ie. Linux and OS X).
- 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. If your command is just too long, consider
making it an ExtUtils::Command::MM function. If your command might
receive many arguments (such as pod2man or pm_to_blib) consider
using split_command() to split it into several, shorter calls.
- 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.
- Travis CI (https://travis-ci.org) is good sources of testing
machines of many perl versions. Accounts are free.
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
=head3 _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.