Helping to clean CPAN: December 2016

11 minute read

… where I get out my virtual broom and sweep up cruft I can find in my assigned distribution for this month’s edition of the CPAN Pull Request Challenge.

This month’s module: Math::Int128

Math::Int128 allows one to manipulate 128 bits integers in Perl.

First impressions

In this section I try to get a feeling for the state of the module, how up to date it is, how often people are contributing to it, how many other distributions are depending on it, how many bugs/issues it currently has, what the CPANTS kwalitee is, etc.

The impression is of stable software which merely needs to be tested on more platforms so as to improve portability.

Initial inspection of the source code

After forking the repo and cloning a local copy, I have a look at the project to see what build system it uses, if the test suite works and the tests pass, if it could do with a Travis-CI config file (or if present, if it can be updated). The initial inspection often gives inspiration for the first batch of pull requests.

  • already configured for Travis. Add Travis-Badge to GitHub page?
  • uses Dist::Zilla
  • dzil authordeps --missing | cpanm works ok
  • there seem to be lots of dependencies for a small dist
  • dzil test fails due to a missing LICENSE file even though it exists
[@DROLSKY/CopyFilesFromBuild] Cannot copy LICENSE from build: file does not exist
[@DROLSKY/CopyFilesFromBuild] Cannot copy LICENSE from build: file does not exist at /home/cochrane/perl5/perlbrew/perls/perl-5.20.3/lib/site_perl/5.20.3/x86_64-linux/Moose/Meta/Method/ line 110.
  • submitted a fix to this issue in PR#17

  • perlver . says the minimum version of perl is v5.13.2; the specified minimum version is 5.6. perlver thus exits with an error. A recommended fix was submitted in PR#16.
  • uses Travis-CI, however the list of Perls could be extended. List of Perls extended in PR#10.
  • would be nice to have setup instructions for a development environment in the
  • interestingly enough, the Travis builds are set up via the travis/ script in the dist. Travis doesn’t use Dist::Zilla at all…
  • running perl Makefile.PL; make; make test gave the error that Math::Int64 was missing. This is installed explicitly in the Travis setup script which would explain why the dist builds and tests correctly on Travis.
  • uses Dist::Zilla::Plugin::MakeMaker::Awesome to generate the Makefile.PL.
  • adding Math::Int64 to the list of DevelopRequires in dist.ini, then running dzil listdeps --missing | cpanm to install the missing package, then needed to run dzil build and copy the generated Makefile.PL from .build/latest into the working directory so that perl Makefile.PL; make; make test ran correctly.
  • removing the -remove = License line from dist.ini allows dzil test to run successfully to completion.
  • noticed that dzil test shows missing deps.
  • found a cpanfile in the dist…
  • looks like the module actually uses carton for dependency management.
  • nope, the cpanfile is autogenerated. Then it gets used in the 00-report-prereqs.t test, which then gives a warning about missing required prereqs. Which test suite is actually used?
  • the development setup isn’t clear. How should one install deps? Via dzil authordeps? Via cpanm --installdeps .? Or should carton be used (which only installs locally and doesn’t use cpanm)?
  • it turns out that there’s an automatically generated file…
  • the dzil incantation required in order to install all development-related dependenices is: dzil listdeps --author --missing | cpanm

It’s a bit confusing as to how to build the dist, however once one finds out that a file is created as part of the dzil build process, one can find out how to build the project. The problem was working out how to fix the initial errors generated when running dzil so that this file could be created so that one could work out how to build the dist in a development environment. Perhaps it would be a good idea to add a quick start guide for potential developers in the README.

Code Coverage

Looking at the code coverage can give an indication of code quality. If the project is well covered, this means most changes made in pull requests can be made with some confidence that any problems will be caught by the test suite. If the code coverage is low, then this is something that one could address as a pull request (or set of pull requests).

In EUMM and Build::Module projects, one simply needs to install Devel::Cover and run

$ cover -test

In Dist::Zilla projects, one needs to install the Dist::Zilla::App::Command::cover plugin, after which the code coverage can be checked via:

$ AUTHOR_TESTING=1 dzil cover

In this distribution, the coverage is:

97.8% total statement coverage; 96.7% total coverage.

which is excellent and can’t really be improved upon.

POD checks

The utility podchecker searches through Perl source code for POD which might not conform to the POD standard, and thus not necessarily be parseable by all POD parsers. Fixing any issues found by podchecker has the positive effect of also removing any warnings noted in the project’s documentation displayed on MetaCPAN.

Running podchecker gives the following errors and warnings:

$ find ./ -name '*.pm' -or -name '*.pod' | xargs podchecker |& grep ERROR
ERROR: =end without =begin at line 31 in file ./inc/Config/
ERROR: =end without =begin at line 58 in file ./inc/Config/
ERROR: unresolved internal link 'Limitations' at line 707 in file ./inc/Capture/
$ find ./ -name '*.pm' -or -name '*.pod' | xargs podchecker |& grep WARN
WARNING: =head2 without preceding higher level at line 29 in file ./inc/Config/
WARNING: =head2 without preceding higher level at line 56 in file ./inc/Config/
WARNING: line containing nothing but whitespace in paragraph at line 1672 in file ./inc/Config/

All of the errors and warnings come from files included as part of the distribution, however coming from other distributions. Perhaps the issues have been fixed in the upstream dists, nevertheless, this means there are no POD issues in the code of the current dist.


Check for trailing whitespace

Some projects consider this a must, and will disallow commits to be submitted which contain trailing whitespace (the Linux kernel is an example project where trailing whitespace isn’t permitted). Other projects see whitespace cleanup as simply nit-picking. Either way one sees it personally, this could be a useful pull request to a project, so it’s worthwhile fixing and submitting; the worst that can happen is that the pull request is closed unmerged.

To look for files with trailing whitespace, run git grep '\s\+$'. It can be helpful to load the files found directly into vim:

$ vim $(git grep '\s\+$' | cut -d':' -f1 | sort | uniq)

The list of files to fix was:


The files under inc/ are actually from other dists, so can be ignored. The LICENSE file is automatically generated, so it too can be ignored. The remaining files can thus be cleaned up. The whitespace issues were fixed in PR#12.

Add files to .gitignore

The files generated by Devel::Cover needed to be ignored as well as the automatically generated file. These changes were incorporated into PR#11. DROLSKY made a note that the file should really be in the repository. The change ignoring this file was removed from PR#11 and the file added in PR#15.


Perl::Critic will show up many potential issues for Perl code. By simply running perlcritic on the lib and t directories, one can get a further handle on the code’s quality.

$ perlcritic lib
$ perlcritic t

No problems found at the default perlcritic severity level in lib/ or t/. This dist has Perl files also under benchmarks and travis. There is one strictures issue found in benchmarks/ The strictures issue was fixed in PR#13.

Stale URLs

Links to websites can go out of date, so it’s a good idea to see if they need updating or removing. A quick grep finds all the links. After which, we just need to see which links need fixing, if any.

$ git grep 'http://\|https://\|ftp://\|git://'

Links look ok.

This probably also sits in the nit-picking category for some people, however, copyright dates (theoretically) need to be kept up to date. The appropriate copyright year is usually the year of the last release. However, if a release looks imminent, then the current year is likely to be the right candidate. Some distributions put the author’s email address on the same line as the copyright date, hence this needs to be checked as well.

Here we do a case-insensitive grep over the source for the word “copyright”, the line of which we check for the existence of a year (i.e. 4 digits), look for the appropriate year and then clean up the grep results to get something we can pass directly to vim.

$ git grep -i copyright
$ vim $(git grep -i copyright | grep -P '\d{4}' | grep -v $COPYRIGHT_YEAR | cut -d':' -f1 | uniq)

Found that Dave Rolsky’s name was missing in the copyright holder information, so added that as well as updated the copyright year to the current release year (2015). This was submitted in PR#14.

$ vim $(git grep -i copyright | grep -P '\d{4}' | grep -v '@' | cut -d':' -f1 | uniq)

This distribution isn’t consistent in its usage of email addresses in copyright statements (and in fact can’t be, since some of the copyright statements are generated automatically), so it doesn’t seem necessary to update this information.

Spell check POD

Good documentation can be a wonder to read. Not everyone’s docs are awesome, however we can keep the error rate to a minimum. A quick spell check will pick up most typos that don’t need to be there and fixing them can help improve the quality of a project.

In general, we want to find all files containing POD and run a spell checker (e.g. aspell) over all files, fixing typos we come across as we go. Not all projects require this much effort, however here’s a general-ish way to look for and check all POD in a project:

$ files_with_pod=$(find ./lib -name '*.pm' -o -name '*.pod' \
                 | xargs podchecker 2>&1 \
                 | grep 'pod syntax' | cut -d' ' -f1)
$ for filename in $files_with_pod
    pod2text $filename > $filename.txt;
    aspell -c $filename.txt;

Now look for .bak file and check differences between it and the output .txt file, the process looks roughly like this:

$ find ./ -name '*.bak'
$ diff -u lib/Path/To/ lib/Path/To/

Then update the appropriate .pm and/or .pod files as necessary.

In this month’s distribution there were only the two files to check and so they could simply be spell checked directly. Sentence flow and grammar also looks good.

Kwalitee tests

Although CPANTS is the main kwalitee reference, one can also run the kwalitee tests locally. One can use the t/99kwalitee.t test script from for this purpose. However, the script only uses Test::Kwalitee which doesn’t cover as many metrics as CPANTS. Test::Kwalitee::Extra uses set of metrics closer to that used on CPANTS, so replace the kwalitee_ok call with simply use Test::Kwalitee::Extra. More information about the many options to Test::Kwalitee::Extra can be found on the MetaCPAN page.

Run the kwalitee tests in an ExtUtils::MakeMaker or Build::Module distribution like so:

$ RELEASE_TESTING=1 prove t/99kwalitee.t

or, if the distribution uses Dist::Zilla, run

$ dzil test --author --release

To use the kwalitee tests in this month’s module, it was necessary to first build the project with dzil build, then enter the build directory Math-Int128-0.23 and then to run the tests via prove, however specifying the test file in the project directory. In other words:

RELEASE_TESTING=1 prove -l ../t/99kwalitee.t
../t/99kwalitee.t .. 1/29
#   Failed test 'meta_yml_declares_perl_version by Module::CPANTS::Kwalitee::MetaYML'
#   at ../t/99kwalitee.t line 12.
#   Detail: This distribution does not declare the minimum perl version in META.yml.
#   Remedy: If you are using Build.PL define the {requires}{perl} = VERSION field. If you are using MakeMaker (Makefile.PL) you should upgrade ExtUtils::MakeMaker to 6.48 and use MIN_PERL_VERSION parameter.  Perl::MinimumVersion can help you determine which version of Perl your module needs.
../t/99kwalitee.t .. 28/29 # Looks like you failed 1 test of 29.
../t/99kwalitee.t .. Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/29 subtests

These errors are in essence a repetition of the warnings found on CPANTS mentioned in the “First impressions” section above. The minimum Perl version issue has been (theoretically) addressed in PR#16.

GitHub issues

There are no open GitHub issues.

RT issues

The single bug mentioned in the RT queue is an as yet unresolved discussion between the two authors of the distribution. It therefore doesn’t seem appropriate for me to weigh in here as well.

Overview of the pull requests made


Wow, within 20 minutes, SALVA had already merged the first pull request!

The remaining PRs, however, have not yet been merged. One was commented on by DROLSKY, which prompted the creation of PR#15. It seems that the stress of the “silly season” has reduced the author’s time for looking at pull requests.

One thing that disappointed me about the result of my PRs to this month’s dist was that I really only picked at the very low hanging fruit and the “nit-picky” stuff. The dist has test failures on Sun and FreeBSD and it probably would have been better to attack things like that so that the dist is more platform independent. At least having fixed an issue like that would have felt more like real progress and not just tidying up. Oh well, maybe next month!