Source

learnvimscriptthehardway / chapters / 43.markdown

Full commit

A New Hope: Plugin Layout with Pathogen

Vim's vanilla layout for plugin files makes sense if you're just adding a file here and there to customize your own Vim experience, but turns into a mess when you want to use plugins other people have written.

In the past, when you wanted to use a plugin someone else wrote you would download the files and place them, one-by-one, into the appropriate directories. You could also use zip or tar to do the placing for you.

There are a few significant problems with this approach:

  • What happens when you want to update a plugin? You can overwrite the old files, but how do you know if the author deleted a file that you now need to delete by hand?
  • What if two plugins happen to have a file with the same name (like utils.vim or something generic like that)? Sometimes you can simply rename it, but if it's in autoload/ or another directory where the names matter you've got to edit the plugin yourself. Not fun.

People came up with several hacks to try to make things easier, like Vimballs. Luckily we don't need to suffer through these ugly hacks any more. Tim Pope created the wonderful Pathogen plugin that makes managing multiple plugins a breeze, as long as plugin authors structure their plugins in a sane way.

Let's take a quick look at how Pathogen works and what we need to do to make our plugin compatible.

Runtimepath

When Vim looks for files in a specific directory, like syntax/, it doesn't just look in a single place. Much like PATH on Linux/Unix/BSD systems, Vim has the runtimepath setting which tells it where to find files to load.

Create a colors directory on your Desktop. Create a file in that directory called mycolor.vim (you can leave it empty for this demonstration). Open Vim and run this command:

:color mycolor

Vim will display an error, because it doesn't know to look on your Desktop for files. Now run this command:

:set runtimepath=/Users/sjl/Desktop

You'll need to change the path to match the path of your own Desktop, of course. Now try the color command again:

:color mycolor

This time Vim doesn't throw an error, because it was able to find the mycolor.vim file. Because the file was blank it didn't actually do anything, but we know it was found because it didn't throw an error.

Pathogen

The Pathogen plugin automatically adds paths to your runtimepath when you load Vim. Any directories inside ~/.vim/bundle/ will each be added to the runtimepath.

This means that each directory inside bundle/ should contain some or all of the standard Vim plugin directories, like colors/ and syntax/. Vim can now load files from each of those directories, which makes it simple to keep each plugin's files in its own directory.

This makes it trivial to update plugins. You can simply blow away the old plugin's directory entirely and replace it with the new version. If you keep your ~/.vim directory under version control (and you should) you can use Mercurial's subrepos or Git's submodules to directly check out each plugin's repository into ~/.vim/bundle/ and then update it with a simple hg pull; hg update or git pull origin master.

Being Pathogen-Compatible

When we write our Potion plugin we want to let our users use it with Pathogen. Doing this is simple: we simply put our files in the appropriate directories inside the plugin's repository!

Our plugin's repository will wind up looking like this:

potion/
    README
    LICENSE
    docs/
        potion.txt
    ftdetect/
        potion.vim
    ftplugin/
        potion.vim
    syntax/
        potion.vim
    ... etc ...

We can put this on GitHub or Bitbucket and users can simply clone it down into bundle/ and everything will just work!

Exercises

Install Pathogen if you haven't already done so.

Create a Mercurial or Git repository for your plugin, called potion. You can put it anywhere you like and symlink it into ~/.vim/bundle/potion/ or just put it directly in ~/.vim/bundle/potion/.

Create README and LICENSE files in the repository and commit them.

Push the repository up to Bitbucket or GitHub.

Read :help runtimepath.