In Item 110: Compile and install your own perls, we showed you how to compile and install several versions of perl so that they don’t conflict with each other and you can use them simultaneously. Since they don’t install their programs, they are left in their $prefix/bin directories. With several perls, each of which has their own modules directories, using tools such as cpan and perldoc can get confusing. Which version of those tools are you using and which perl are they trying to use? Continue reading “Make links to per-version tools”
Category: miscellany
Avoid accidently creating methods from module exports
Perl’s object system is fuzzy. Methods are really just subroutines and classes are just packages, which means that any subroutine in a package is also a method in that class. Your class might have subroutines that you’ve never even noticed, so you end up with methods that you didn’t want in your interface. Continue reading “Avoid accidently creating methods from module exports”
Manage your Perl modules with git
In Item 110: Compile and install your own perls, you saw how to install multiple versions of perl and to maintain each of the installations separately. Doing something with one version of Perl doesn’t affect any of the other versions.
You can take that a step further. Within each installation, you can use a source control system to manage your Perl modules. In this post you’ll use git, which has the advantage that you don’t need a server.
First, install your perl into its own directory:
% ./Configure -des -Dprefix=/usr/local/perls/perl-5.10.1 % make test % make install
Second, before you do anything else with your newly installed perl, put your new directory into source control:
% cd /usr/local/perls/perl-5.10.1 % git init % git add . % git commit -a -m "Initial installation of Perl 5.10.1"
You’re not quite done there, though. You’re on the master branch:
% git branch * master
You want to keep at least one pristine branch that is the initial state of your perl installation. You can always come back to it:
% git checkout -b pristine Switched to a new branch 'pristine'
Leave that branch alone and switch back to master:
% git checkout master Switched to branch 'master'
From here you can do many things, but you probably want to consider the master branch your “stable” branch. You don’t want to commit anything to that branch until you know it works. When you install new modules, use a different branch until you know you want to keep them:
% git checkout -b unstable Switched to a new branch 'unstable' % cpan LWP::Simple % git add . % git commit -a -m "* Installed LWP::Simple"
After using your newly installed modules for awhile and deciding that it’s stable, merge your unstable with master. Once merged, switch back to the unstable branch to repeat the process:
% git checkout master Switched to a new branch 'master' % git merge unstable % git checkout unstable
Anytime that you want to start working with a clean installation, you start at the pristine branch and make a new branch from there:
% git checkout pristine % git checkout -b newbranch
If you aren’t tracking your perl in source control already, just tracking a master and unstable branch can give you an immediate benefit. However, you can take this idea a step further.
With just one perl installation, you can create multiple branches to try out different module installations. Instead of merging these branches, you keep them separate. When you want to test your application with a certain set of modules, you merely switch to that branch and run your tests. When you want to test against a different set, change branches again. That can be quite a bit simpler than managing multiple directories that you have to constantly add or remove from @INC.