Exploring my Emacs packages - Projectile

What is Projectile?

Project homepage : http://batsov.com/projectile/

Projectile is a project interaction library for Emacs. It's not a project management package, in that it doesn't handle task lists, gantt charts or things like that.

In practice, Projectile works as a way to limit functionality to files in whatever project is currently being worked on.

Projects are just a directory and its files which makes things simple. By default Projectile will treat any directory under source control as a project, but adding a .projectile file to a directory will also turn it into a project.

The file list can be filtered to ignore entries, either via .gitignore or in the .projectile file.

What can I use it for?

There's some tasks I perform quite often:

  • Navigating project files
  • Running tests and compilation commands
  • Switching between tests and source files
  • Switching between controllers and views
  • Running grep and occur

And some I do less often:

  • Running a shell in a project's directory
  • Renaming files within a project
  • Jumping to an included file

None of these are particularly time consuming, but I'd still like to streamline them if possible. Let's see if Projectile can help.

Navigating project files

Normally I would use C-x C-f (find-file) to open other files in a project. Projectile provides C-c p f (projectile-find-file), which is a very fast alternative.

Opening files with projectile

Ignored files are automatically filtered from the list and it integrates nicely with Helm.

C-c p d works in a similar way for directories and opens them in dired. C-c p b can be used to switch between project buffers.

Running tests and compilation commands

For most projects I'll have a terminal window open to run tests and compile code. Both of these things can be done using Projectile commands:

  • C-c p P – Runs a test command for the current project.
  • C-c p c – Runs a compilation command for the current project.

Each command will try to figure out the best function for the current project type. There are currently 30 different project types built-in, covering Rails, Symfony, Django and a bunch of other common platforms.

Project types are assigned by searching for specific files in the project root. For example, finding a Makefile file in the root will set the default compile command to make and the default test command to make test.

Projects can set their compile and test commands using Emacs .dir-locals.el.

  • projectile-project-compilation-cmd sets the compilation command
  • projectile-project-test-cmd sets the test command
  • projectile-project-run-cmd sets the run command
  • projectile-project-compilation-dir sets the directory to run compilation commands in.

These will override whatever type Projectile has assigned.

Example: .dir-locals.el for a Common Lisp project

((nil . ((projectile-project-test-cmd . "sbcl --script test.lisp"))))

The .dir-locals.el overrides make it possible to customize projects no matter what language or setup they're using.

Switching between tests and source files

Projectile's C-c p t command works most of the time, but a couple of my projects needed to be tweaked slightly to work properly due to the way test files are named and found.

To find the appropriate test file, Projectile strips the current filename of its path and extension, and then checks for a specific prefix or suffix.

For example:

"project/src/module/my_file.rb" will be stripped down to just "my_file". Ruby projects use "_test" as the suffix, meaning Projectile will attempt to open "my_file_test.rb" wherever it is located.

Some of my projects use the same name for source and test files, but stores them in different directories. It may be possible to extend this behaviour, but I'm still looking into that.

Switching between controllers and views

projectile-rails can be used to switch between models and views within rails projects.

For none-Rails projects, there are a couple of options, although neither are perfect:

  • C-c p a – Switches between files with the same name but a different extension.
  • C-c p g – Jumps to the file at the current point. This worked well for projects that explicitly named view templates.

Running grep and occur

Both of these options are supported and very quick:

  • C-c p s g – Runs grep on the entire project
  • C-c p o – Runs occur on all open project buffers

Running git

C-c p v opens version control for the current project. It automatically works out the best option based on what version control the project is under. For example, projects under git will open magit if installed.

Renaming files

There's no shortcut for renaming files, but being able to quickly open dired for project directories makes the whole process much easier.

Opening a terminal

C-c p ! runs a shell command in the project root. There's no shortcut to open a terminal .

More information

There's a full list of commands available on the Projectile project page: http://batsov.com/projectile/#interactive-commands

This post is part of the "Exploring my Emacs packages" series.

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Exploring my Emacs packages

I've been using Emacs as my primary editor for around 5 years. Over that time I've installed plenty of packages and tweaked numerous settings. There are some packages that I use daily, but others have sat in the background, unused and unloved.

Over the next few weeks I'll be exploring some of those lesser-used packages and learning what they have to offer.

The packages are currently on my list to explore:

Project interaction library. Lots of functionality for moving around projects.
Live web development for Emacs. It can update web pages without reloading them and also features a JavaScript REPL.
Adds auto-complete functionality.
Snippet expansion library.
Major mode for editing HTML. Can handle plenty of template languages.

I'll be updating this list with links to each post.

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