got lib? Lieber Gott! - Hacking Thy Fearful Symmetry

Hacking Thy Fearful Symmetry

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got lib? Lieber Gott!

created: March 1, 2015

A new version of got hit CPAN a few days ago, and it has a brand new feature that is mind-bogglingly awesome. Mind you, the fact that I'm the one who sent its PR might paint me as slightly biased on the matter. But let's not dwell too much on the shameless self-promotion going on here, and instead let's turn our gazes to that promised successor to sliced bread.

Before, though, a quick recap: got is a lovely little utility that help you manage your git repositories. At its core, it keeps a list of managed local git repositories and, upon request, will let you know of the status of each of them (dirty, all neatly commited locally, in sync with the remote origin) or update all the remote origins en masse.

That, by itself, is wonderful, but that core goodness comes with even more delicious sprinkles: got can open shells in specified projects, or open a whole slew of them in tmux windows. It can also fork stuff from GitHub. In short, it's growing to be a very nice repositories command center...

... and the growth just went one size bigger. You see, either at $work or on my yak shaving expeditions, I tend to end up dealing with sizable codebases spanning many repositories. Which means that a truckload of custom library paths are usually required to get any of their scripts to work.

At first, of course, I went for the direct approach:

$ perl -Ilib -I/and/this/other/lib -I../and/yet/another/lib bloody/script.pl

Then got annoyed with super-long commands, so stuffed all those libs in PERL5LIB.

# warning: this is fish, not bash
$ set -x PERL5LIB lib /and/this/other/lib ../and/yet/another/lib

$ perl bloody/script.pl

And then got fed up with remembering which bunch of libraries I need for this project or that project, so I looked into ylib and Devel::Local. Truth to be told, they are fairly good solutions. But I thought that since got is already my repository shepherd, wouldn't it be nice if it could take away even more of the humdrum of the library dance?

Well, thanks to got tag and got lib, it can. Lemme demonstrate.

Let's say that I try to run Galuga from a Dancer-less stock perlbrew install.

15:26 yanick@enkidu ~/work/perl-modules/Galuga
$ perl bin/app.pl
Can't locate Dancer2.pm in @INC [...]

I'm missing Dancer2. And probably a bunch of plugins. Very sad situation. Fortunately, I have all that I need in local repositories, which I had the good sense to tag as being dancer2-related:

$  got list --tag dancer2
8) Dancer2                   git   git@github.com:PerlDancer/Dancer2.git
9) Dancer2-Template-Caribou  git   git@github.com:yanick/Dancer2-Template-Caribou.git
22) dancer2-plugin-feed       git   git@github.com:yanick/Dancer-Plugin-Feed.git

Cue in got lib, which will help me setting up that PERL5LIB.

# got lib can expand from a single repo
$ got lib Web-Query/lib
/home/yanick/work/perl-modules/Web-Query/lib

# or from a whole tagged set
$ got lib @dancer2/lib
/home/yanick/work/perl-modules/dancer/Dancer2/lib:/home/yanick/work/perl-modules/dancer/Dancer2-Template-Caribou/lib:/home/yanick/work/perl-modules/dancer/Dancer2-Plugin-Feed/lib

# or can pass a plain ol' directory through 
$ got lib ./lib
/home/yanick/work/perl-modules/Galuga/lib

# all together now
$ got lib Web-Query/lib @dancer2/lib ./lib
/home/yanick/work/perl-modules/Web-Query/lib:/home/yanick/work/perl-modules/dancer/Dancer2/lib:/home/yanick/work/perl-modules/dancer/Dancer2-Template-Caribou/lib:/home/yanick/work/perl-modules/dancer/Dancer2-Plugin-Feed/lib:/home/yanick/work/perl-modules/Galuga/lib

Once we're happy, the list of library paths can be put in a .gotlib file to be automatically picked by got lib.

$ cat .gotlib
./lib
@dancer2/lib
Web-Query/lib

$ got lib
/home/yanick/work/perl-modules/Galuga/lib:/home/yanick/work/perl-modules/dancer/Dancer2/lib:/home/yanick/work/perl-modules/dancer/Dancer2-Template-Caribou/lib:/home/yanick/work/perl-modules/dancer/Dancer2-Plugin-Feed/lib:/home/yanick/work/perl-modules/Web-Query/lib

And, finally, we can use that to populate PERL5LIB.

# using the 'fish' shell
# for 'bash' you'll want 'export PERL5LIB=`got lib`'
$ set -x PERL5LIB (got lib)

# TADAH!
$ perl bin/app.pl
[ ... Dancer2 is found and everybody's happy ... ]

Being the lazy person I am, I can also let my shell do the work of doing all that if a .gotlib file is present in the current directory:

$ cat ~/.config/fish/functions/__got_lib.fish
function __got_lib --on-variable PWD --description 'set got lib'

    status --is-command-substitution; and return

    test -f '.gotlib'; or return

    set -l mylib (got lib)
    echo "setting PERL5LIB to $mylib"

    set -x PERL5LIB $mylib
end

$ cd Galuga/
setting PERL5LIB to /home/yanick/work/perl-modules/Galuga/lib:/home/yanick/work/perl-modules/dancer/Dancer2/lib:/home/yanick/work/perl-modules/dancer/Dancer2-Template-Caribou/lib:/home/yanick/work/perl-modules/dancer/Dancer2-Plugin-Feed/lib:/home/yanick/work/perl-modules/Web-Query/lib

Neat, isn't?

Oh, and before I sign off this blog entry, a last note. You probably noticed that the '/lib' subdirectories are explicitly given. That was a conscious decision of mine. In part to allow for special cases (like adding test-specific libs via @dancer/t/lib), but also to keep the door open for got lib to be used for non-Perl projects. I won't go into details here, but just to give you a teaser... say you are in a repo building .so files that you want to append to your LD_LIBRARY_PATH. Then this will do the trick:

$ echo $LD_LIBRARY_PATH
/usr/kde/3.5/lib /usr/kde/3.5/lib

$ set -x LD_LIBRARY_PATH  ( got lib --libvar LD_LIBRARY_PATH ./build/ )

$ echo $LD_LIBRARY_PATH
/home/yanick/work/perl-modules/Galuga/build:/usr/kde/3.5/lib

Enjoy!

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About the author

Yanick Champoux
Perl necrohacker , ACP writer, orchid lover. Slightly bonker all around.