Ever wonder how many CPAN distributions use Module::Build, or Module::Install? Or how common the different ways Changes, ChangeLog, Changelog, etc. show up in a distribution? Or how many distributions use a particular expression in code?

I wrote App::CPAN::Mini::Visit and the visitcpan tool to make answering such questions a lot easier.

It provides a command line tool that unpacks each distribution tarball in a CPAN::Mini repository, visits the resulting directory, and executes another program. For example, listing all distributions that contain Build.PL:

$ visitcpan --append=dist -- perl -E 'say shift if -f "Build.PL"'

AASSAD/Catalyst-Helper-Controller-Scaffold-HTML-Template-0.03.tar.gz
ABERGMAN/Alien-0.91.tar.gz
ABERGMAN/File-Find-Random-0.5.tar.gz
ABERGMAN/SVL-0.29.tar.gz
...
[download]

Clearly, if I were running frequent analyses, I might just use CPAN::Mini::Extract and keep all the tarballs extracted, but since I only occasionally have questions like this, I'm willing to make the space/time tradeoff.

Oh, and to answer that first question, here's how many distributions use each style of installer:

$ visitcpan -- perl -E 'if (-f "inc/Module/Install.pm") { say "MI" } e
+lsif (-f "Build.PL") { say "MB" } elsif (-f "Makefile.PL") { say "EUM
+M" }' | perl -E 'while (<>) { chomp; $cnt{$_}++ } say "$_: $cnt{$_}" 
+for keys %cnt'

MI: 2306
MB: 2675
EUMM: 11781
[download]

Looks like Module::Install has almost caught up to Module::Build. Impressive!