Projectionist provides granular project configuration using "projections". What are projections? Let's start with an example.

A while back I went and made a bunch of plugins for working with rbenv. Here's what a couple of them look like:

~/.rbenv/plugins $ tree
.
├── rbenv-ctags
│   ├── bin
│   │   └── rbenv-ctags
│   └── etc
│       └── rbenv.d
│           └── install
│               └── ctags.bash
└── rbenv-sentience
    └── etc
        └── rbenv.d
            └── install
                └── sentience.bash

As you can see, rbenv plugins have hooks in etc/rbenv.d/ and commands in bin/ matching rbenv-*. Here's a projectionist configuration for that setup:

let g:projectionist_heuristics = {
      \   "etc/rbenv.d/|bin/rbenv-*": {
      \     "bin/rbenv-*": {
      \        "type": "command",
      \        "template": ["#!/usr/bin/env bash"],
      \     },
      \     "etc/rbenv.d/*.bash": {"type": "hook"}
      \   }
      \ }

The key in the outermost dictionary says to activate for any directory containing a subdirectory etc/rbenv.d/ or files matching bin/rbenv-*. The corresponding value contains projection definitions. Here, two projections are defined. The first creates an :Ecommand navigation command and provides boilerplate to pre-populate new files with, and the second creates an :Ehook command.

See :help projectionist for the authoritative documentation. Here are some highlights.

In the above example, we used the global g:projectionist_heuristics to declare projections based on requirements in the root directory. If that's not flexible enough, you can use the autocommand based API, or create a .projections.json in the root of the project.

Navigation commands encapsulate editing filenames matching certain patterns. Here are some examples for this very project:

{
  "plugin/*.vim": {"type": "plugin"},
  "autoload/*.vim": {"type": "autoload"},
  "doc/*.txt": {"type": "doc"},
  "README.markdown": {"type": "doc"}
}

With these in place, you could use :Eplugin projectionist to edit plugin/projectionist.vim and :Edoc projectionist to edit doc/projectionist.txt. If no argument is given, it will edit an alternate file of that type (see below) or a projection without a glob. So in this example :Edoc would default to editing README.markdown.

The E stands for edit. You also get S, V, and T variants that split, vsplit, and tabedit.

Tab complete is smart. Not quite "fuzzy finder" smart but smart nonetheless. (On that note, fuzzy finders are great, but I prefer the navigation command approach when there are multiple categories of similarly named files.)

Projectionist provides :A, :AS, :AV, and :AT to jump to an "alternate" file, based on ye olde convention originally established in a.vim. Here's an example configuration for Maven that allows you to jump between the implementation and test:

{
  "src/main/java/*.java": {"alternate": "src/test/java/{}.java"},
  "src/test/java/*.java": {"alternate": "src/main/java/{}.java"}
}

In addition, the navigation commands (like :Eplugin above) will search alternates when no argument is given to edit a related file of that type.

Bonus feature: :A {filename} edits a file relative to the root of the project.

Check out these examples for a minimal Ruby project:

{
  "*": {"make": "rake"},
  "spec/*_spec.rb": {"dispatch": "rspec {file}"}
}

That second one sets the default for dispatch.vim. Plugins can use projections for their own configuration.

Install using your favorite package manager, or use Vim's built-in package support:

mkdir -p ~/.vim/pack/tpope/start
cd ~/.vim/pack/tpope/start
git clone https://tpope.io/vim/projectionist.git
vim -u NONE -c "helptags projectionist/doc" -c q

Why not a clearer filename like .vim_projections.json?

Nothing about the file is Vim specific. See projectionist for an example of another tool that uses it.

Copyright © Tim Pope. Distributed under the same terms as Vim itself. See :help license.