# Projects

## Supported Project Types

One of the main goals of Projectile is to operate on a wide range of project types without the need for any configuration. To achieve this it contains a lot of project detection logic and project type specific logic.

Broadly speaking, Projectile identifies projects like this:

- Directories that contain the special `.projectile` file

- Directories under version control (e.g. a Git repo)

- Directories that contain some project description file (e.g. a `Gemfile` for Ruby projects or `pom.xml` for Java maven-based projects)

While Projectile aims to recognize most project types out-of-the-box, it’s also extremely flexible configuration-wise, and you can easily alter the project detection logic.

Tip | If you’d like to override the default project detection functions you should check out `projectile-project-root-functions`. We’ll discuss how to tweak in more details later in the documentation.

### Version Control Systems

Projectile considers most version-controlled repos to be a project. Out of the box Projectile supports:

- Git

- Mercurial

- Bazaar

- Subversion

- CVS

- Fossil

- Darcs

### File markers

Projectile considers many files to denote the root of a project. Usually those files are the configuration files of various build tools. Out of the box the following are supported:

File | Project Type
--- | ---
rebar.config | Rebar project file
project.clj | Leiningen project file
build.boot | Boot-clj project file
deps.edn | Clojure CLI project file
SConstruct | Scons project file
default.nix | Nix project file
flake.nix | Nix flake project file
pom.xml | Maven project file
build.sbt | SBT project file
build.sc | Mill project file
gradlew | Gradle wrapper script
build.gradle | Gradle project file
.ensime | Ensime configuration file
Gemfile | Bundler file
requirements.txt | Pip file
setup.py | Setuptools file
tox.ini | Tox file
composer.json | Composer project file
Cargo.toml | Cargo project file
mix.exs | Elixir mix project file
stack.yaml | Haskell’s stack tool based project
dune-project | OCaml Dune project file
info.rkt | Racket package description file
DESCRIPTION | R package description file
TAGS | etags/ctags are usually in the root of project
GTAGS | GNU Global tags
configure.in | autoconf old style
configure.ac | autoconf new style
cscope.out | cscope
Makefile | Make
CMakeLists.txt | CMake
WORKSPACE | Bazel workspace file
debian/control | Debian package dpkg control file

There’s also Projectile’s own `.projectile` which serves both as a project marker and a configuration file. We’ll talk more about later in this section.

## Adding Custom Project Types

If a project you are working on is recognized incorrectly or you want to add your own type of projects you can add following to your Emacs initialization code

    (projectile-register-project-type 'npm '("package.json")
                                      :project-file "package.json"
    				  :compile "npm install"
    				  :test "npm test"
    				  :run "npm start"
    				  :test-suffix ".spec")

What this does is:

1. add your own type of project, in this case `npm` package.

2. add a list of files and/or folders in a root of the project that helps to identify the type, in this case it is only `package.json`. This can also be a function which takes a project root as argument and verifies whether that directory has the correct project structure for the type.

3. add project-file, which is typically the primary project configuration file. In this case that’s `package.json`. The value can contain wildcards and/or be a list containing multiple project files to look for.

4. add compile-command, in this case it is `npm install`.

5. add test-command, in this case it is `npm test`.

6. add run-command, in this case it is `npm start`.

7. add test files suffix for toggling between implementation/test files, in this case it is `.spec`, so the implementation/test file pair could be `service.js`/`service.spec.js` for example.

Let’s see a couple of more complex examples.

    ;; .NET C# or F# projects
    (projectile-register-project-type 'dotnet #'projectile-dotnet-project-p
                                      :project-file '("?*.csproj" "?*.fsproj")
                                      :compile "dotnet build"
                                      :run "dotnet run"
                                      :test "dotnet test")

This example uses projectile-dotnet-project-p to validate the project’s structure. Since C# and F# project files have names containing the name of the project, it uses a list of wildcards to specify the different valid project-file name patterns.

    ;; Ruby + RSpec
    (projectile-register-project-type 'ruby-rspec '("Gemfile" "lib" "spec")
                                      :project-file "Gemfile"
                                      :compile "bundle exec rake"
                                      :src-dir "lib/"
                                      :test "bundle exec rspec"
                                      :test-dir "spec/"
                                      :test-suffix "_spec")

    ;; Ruby + Minitest
    (projectile-register-project-type 'ruby-test '("Gemfile" "lib" "test")
                                      :project-file "Gemfile"
                                      :compile "bundle exec rake"
                                      :src-dir "lib/"
                                      :test "bundle exec rake test"
                                      :test-suffix "_test")

    ;; Rails + Minitest
    (projectile-register-project-type 'rails-test '("Gemfile" "app" "lib" "db" "config" "test")
                                      :project-file "Gemfile"
                                      :compile "bundle exec rails server"
                                      :src-dir "lib/"
                                      :test "bundle exec rake test"
                                      :test-suffix "_test")

    ;; Rails + RSpec
    (projectile-register-project-type 'rails-rspec '("Gemfile" "app" "lib" "db" "config" "spec")
                                      :project-file "Gemfile"
                                      :compile "bundle exec rails server"
                                      :src-dir "lib/"
                                      :test "bundle exec rspec"
                                      :test-dir "spec/"
                                      :test-suffix "_spec")

All those projects are using `Gemfile` (`bundler`'s project file), but they have different directory structures.

Below is a listing of all the available options for `projectile-register-project-type`:

Option | Documentation
--- | ---
:project-file | A file, relative to the project root, typically the main project file (e.g. `pom.xml` for Maven projects).
:compilation-dir | A path, relative to the project root, from where to run the tests and compilation commands.
:compile | A command to compile the project.
:configure | A command to configure the project. `%s` will be substituted with the project root.
:install | A function to install the project.
:package | A function to package the project.
:run | A command to run the project.
:src-dir | A path, relative to the project root, where the source code lives. A function may also be specified which takes one parameter - the directory of a test file, and it should return the directory in which the implementation file should reside. This option is only used for implementation/test toggling.
:test | A command to test the project.
:test-dir | A path, relative to the project root, where the test code lives. A function may also be specified which takes one parameter - the directory of a file, and it should return the directory in which the test file should reside. This option is only used for implementation/test toggling.
:test-prefix | A prefix to generate test files names.
:test-suffix | A suffix to generate test files names.
:related-files-fn | A function to specify test/impl/other files in a more flexible way.

#### Returning Projectile Commands from a function

You can also pass a symbolic reference to a function into your project type definition if you wish to define the compile command dynamically:

    (defun my/compile-command ()
      "Returns a String representing the compile command to run for the given context"
      (cond
       ((and (eq major-mode 'java-mode)
             (not (string-match-p (regexp-quote "\\.*/test/\\.*") (buffer-file-name (current-buffer)))))
        "./gradlew build")
       ((eq major-mode 'web-mode)
        "./gradlew compile-templates")
       ))

    (defun my/test-command ()
      "Returns a String representing the test command to run for the given context"
      (cond
       ((eq major-mode 'js-mode) "grunt test") ;; Test the JS of the project
       ((eq major-mode 'java-mode) "./gradlew test") ;; Test the Java code of the project
       ((eq major-mode 'my-mode) "special-command.sh") ;; Even Special conditions/test-sets can be covered
       ))

    (projectile-register-project-type 'has-command-at-point '("file.txt")
                                      :compile 'my/compile-command
                                      :test 'my/test-command)

If you would now navigate to a file that has the `*.java` extension under the `./tests/` directory and hit `C-c c p` you will see `./gradlew build` as the suggestion. If you were to navigate to a HTML file the compile command will have switched to `./gradlew compile-templates`.

This works for:

- `:configure`

- `:compile`

- `:compilation-dir`

- `:run`

Note that your function has to return a string to work properly.

### Related file location

The `:test-prefix` and `:test-suffix` will work regardless of file extension or directory path should and be enough for simple projects. The `projectile-other-file-alist` variable can also be set to find other files based on the extension.

For fine-grained control of implementation/test toggling, the `:test-dir` option of a project may take a function of one parameter (the implementation directory absolute path) and return the directory of the test file. This in conjunction with the options `:test-prefix` and `:test-suffix` will then be used to determine the full path of the test file. This option will always be respected if it is set.

Similarly, the `:src-dir` option, the analogue of `:test-dir`, may also take a function and exhibits exactly the same behaviour as above except that its parameter corresponds to the directory of a test file and it should return the directory of the corresponding implementation file.

It’s recommended that either both or neither of these options are set to functions for consistent behaviour.

Alternatively, for flexible file switching across a range of projects, the `:related-files-fn` option set to a custom function or a list of custom functions can be used. The custom function accepts the relative file name from the project root and it should return related file information as a plist with the following optional key/value pairs:

Key | Value | Command applicable
--- | --- | ---
:impl | matching implementation file if the given file is a test file | projectile-toggle-between-implementation-and-test, projectile-find-related-file
:test | matching test file if the given file has test files. | projectile-toggle-between-implementation-and-test, projectile-find-related-file
:other | any other files if the given file has them. | projectile-find-other-file, projectile-find-related-file
:foo | any key other than above | projectile-find-related-file

For each value, following type can be used:

Type | Meaning
--- | ---
string / a list of strings | Relative paths from the project root. The paths which actually exist on the file system will be matched.
a function | A predicate which accepts a relative path as the input and return t if it matches.
nil | No match exists.

Notes:

1. For a big project consisting of many source files, returning strings instead of a function can be fast as it does not iterate over each source file.

2. There is a difference in behaviour between no key and `nil` value for the key. Only when the key does not exist, other project options such as `:test_prefix` or `projectile-other-file-alist` mechanism is tried.

3. If the `:test-dir` option is set to a function, this will take precedence over any value for `:related-files-fn` set when `projectile-toggle-between-implementation-and-test` is called.

#### Example - Same source file name for test and impl

    (defun my/related-files (path)
      (if (string-match (rx (group (or "src" "test")) (group "/" (1+ anything) ".cpp")) path)
          (let ((dir (match-string 1 path))
                (file-name (match-string 2 path)))
            (if (equal dir "test")
                (list :impl (concat "src" file-name))
              (list :test (concat "test" file-name)
                    :other (concat "src" file-name ".def"))))))

    (projectile-register-project-type
       ;; ...
       :related-files-fn #'my/related-files)

With the above example, src/test directory can contain the same name file for test and its implementation file. For example, "src/foo/abc.cpp" will match to "test/foo/abc.cpp" as test file and "src/foo/abc.cpp.def" as other file.

#### Example - Different test prefix per extension

A custom function for the project using multiple programming languages with different test prefixes.

    (defun my/related-files(file)
      (let ((ext-to-test-prefix '(("cpp" . "Test")
                                  ("py" . "test_"))))
        (if-let ((ext (file-name-extension file))
                 (test-prefix (assoc-default ext ext-to-test-prefix))
                 (file-name (file-name-nondirectory file)))
            (if (string-prefix-p test-prefix file-name)
                (let ((suffix (concat "/" (substring file-name (length test-prefix)))))
                  (list :impl (lambda (other-file)
                                (string-suffix-p suffix other-file))))
              (let ((suffix (concat "/" test-prefix file-name)))
                (list :test (lambda (other-file)
                              (string-suffix-p suffix other-file))))))))

`projectile-find-related-file` command is also available to find and choose related files of any kinds. For example, the custom function can specify the related documents with ':doc' key. Note that `projectile-find-related-file` only relies on `:related-files-fn` for now.

### Related file custom function helper

`:related-files-fn` can accept a list of custom functions to combine the result of each custom function. This allows users to write several custom functions and apply them differently to projects.

Projectile includes a couple of helpers to generate commonly used custom functions.

Helper name and params | Purpose
--- | ---
groups KIND GROUPS | Relates files in each group as the specified kind.
extensions KIND EXTENSIONS | Relates files with extensions as the specified kind.
test-with-prefix EXTENSION PREFIX | Relates files with prefix and extension as :test and :impl.
test-with-suffix EXTENSION SUFFIX | Relates files with suffix and extension as :test and :impl.

Each helper means `projectile-related-files-fn-helper-name` function.

#### Example usage of projectile-related-files-fn-helpers

    (setq my/related-files
          (list
           (projectile-related-files-fn-extensions :other '("cpp" "h" "hpp"))
           (projectile-related-files-fn-test-with-prefix "cpp" "Test")
           (projectile-related-files-fn-test-with-suffix "el" "_test")
           (projectile-related-files-fn-groups
            :doc
            '(("doc/common.txt"
               "src/foo.h"
               "src/bar.h")))))

    (projectile-register-project-type
       ;; ...
       :related-files-fn my/related-files)

### Editing Existing Project Types

You can also edit specific options of already existing project types:

    (projectile-update-project-type
     'sbt
     :related-files-fn
     (list
      (projectile-related-files-fn-test-with-suffix "scala" "Spec")
      (projectile-related-files-fn-test-with-suffix "scala" "Test"))
     :test-prefix nil
     :precedence 'high)

This will change the value of the `related-files-fn` option, remove the `test-prefix` option and `:precedence 'high` sets the sbt project type to be chosen in preference to other potentially clashing project types (a value `'low` would do the opposite).

### `:test-dir`/`:src-dir` vs `:related-files-fn`

Whilst setting the `:test-dir` and `:src-dir` to strings is sufficient for most purposes, using functions can give more flexibility. As an example consider (also using `f.el`):

    (defun my-get-python-test-file (impl-file-path)
      "Return the corresponding test file directory for IMPL-FILE-PATH"
      (let* ((rel-path (f-relative impl-file-path (projectile-project-root)))
             (src-dir (car (f-split rel-path))))
        (cond ((f-exists-p (f-join (projectile-project-root) "test"))
               (projectile-complementary-dir impl-file-path src-dir "test"))
              ((f-exists-p (f-join (projectile-project-root) "tests"))
               (projectile-complementary-dir impl-file-path src-dir "tests"))
              (t (error "Could not locate a test file for %s!" impl-file-path)))))

    (defun my-get-python-impl-file (test-file-path)
      "Return the corresponding impl file directory for TEST-FILE-PATH"
      (if-let* ((root (projectile-project-root))
                (rel-path (f-relative test-file-path root))
                (src-dir-guesses `(,(f-base root) ,(downcase (f-base root)) "src"))
                (src-dir (cl-find-if (lambda (d) (f-exists-p (f-join root d)))
                                     src-dir-guesses)))
          (projectile-complementary-dir test-file-path "tests?" src-dir)
        (error "Could not locate a impl file for %s!" test-file-path)))

    (projectile-update-project-type
     'python-pkg
     :src-dir #'my-get-python-impl-dir
     :test-dir #'my-get-python-test-dir)

This attempts to recognise projects using both `test` and `tests` as top level directories for test files. An alternative using the `related-files-fn` option could be:

    (projectile-update-project-type
     'python-pkg
     :related-files-fn
     (list
      (projectile-related-files-fn-test-with-suffix "py" "_test")
      (projectile-related-files-fn-test-with-prefix "py" "test_")))

In fact this is a lot more flexible in terms of finding test files in different locations, but will not create test files for you.

## Customizing Project Detection

Project detection is pretty simple - Projectile just runs a list of project detection functions (`projectile-project-root-functions`) until one of them returns a project directory.

This list of functions is customizable, and while Projectile has some defaults for it, you can tweak it however you see fit.

Let’s take a closer look at `projectile-project-root-functions`:

    (defcustom projectile-project-root-functions
      '(projectile-root-local
        projectile-root-marked
        projectile-root-bottom-up
        projectile-root-top-down
        projectile-root-top-down-recurring)
      "A list of functions for finding project roots."
      :group 'projectile
      :type '(repeat function))

The important thing to note here is that the functions get invoked in their order on the list, so the functions earlier in the list will have a higher precedence with respect to project detection. Let’s examine the defaults:

- `projectile-root-local` looks for project path set via the buffer-local variable `projectile-project-root`. Typically you’d set this variable via `.dir-locals.el` and it will take precedence over everything else.

- `projectile-root-marked` looks for `.projectile` (or whatever you’ve set as the value of `projectile-dirconfig-file`). The idea is that normally if you have a `.projectile` file you’d like it to override the normal project root discovery logic.

- `projectile-root-bottom-up` will start looking for a project marker file/folder(e.g. `.projectile`, `.hg`, `.git`) from the current folder (a.k.a. `default-directory` in Emacs lingo) up the directory tree. It will return the first match it discovers. The assumption is pretty simple - the root marker appear only once, at the root folder of a project. If a root marker appear in several nested folders (e.g. you’ve got nested git projects), the bottom-most (closest to the current dir) match has precedence. You can customize the root markers recognized by this function via `projectile-project-root-files-bottom-up`

- `projectile-root-top-down` is similar, but it will return the top-most (farthest from the current directory) match. It’s configurable via `projectile-project-root-files` and all project manifest markers like `pom.xml`, `Gemfile`, `project.clj`, etc go there.

- `projectile-root-top-down-recurring` will look for project markers that can appear at every level of a project (e.g. `Makefile` or `.svn`) and will return the top-most match for those.

The default ordering should work well for most people, but depending on the structure of your project you might want to tweak it.

Re-ordering those functions will alter the project detection, but you can also replace the list. Here’s how you can delegate the project detection to Emacs’s built-in function `vc-root-dir`:

    ;; we need this wrapper to match Projectile's API
    (defun projectile-vc-root-dir (dir)
      "Retrieve the root directory of the project at DIR using `vc-root-dir'."
      (let ((default-directory dir))
        (vc-root-dir)))

    (setq projectile-project-root-functions '(projectile-vc-root-dir))

Similarly, you can leverage the built-in `project.el` like this:

    ;; we need this wrapper to match Projectile's API
    (defun projectile-project-current (dir)
      "Retrieve the root directory of the project at DIR using `project-current'."
      (cdr (project-current nil dir)))

    (setq projectile-project-root-functions '(projectile-project-current))

## Ignoring files

Warning | The contents of `.projectile` are ignored when using the `alien` project indexing method.

If you’d like to instruct Projectile to ignore certain files in a project, when indexing it you can do so in the `.projectile` file by adding each path to ignore, where the paths all are relative to the root directory and start with a slash. Everything ignored should be preceded with a `-` sign. Alternatively, not having any prefix at all also means to ignore the directory or file pattern that follows. Here’s an example for a typical Rails application:

    -/log
    -/tmp
    -/vendor
    -/public/uploads

This would ignore the folders only at the root of the project. Projectile also supports relative pathname ignores:

    -tmp
    -*.rb
    -*.yml
    -models

You can also ignore everything except certain subdirectories. This is useful when selecting the directories to keep is easier than selecting the directories to ignore, although you can do both. To select directories to keep, that means everything else will be ignored.

Example:

    +/src/foo
    +/tests/foo

Keep in mind that you can only include subdirectories, not file patterns.

If both directories to keep and ignore are specified, the directories to keep first apply, restricting what files are considered. The paths and patterns to ignore are then applied to that set.

Finally, you can override ignored files. This is especially useful when some files ignored by your VCS should be considered as part of your project by projectile:

    !/src/foo
    !*.yml

When a path is overridden, its contents are still subject to ignore patterns. To override those files as well, specify their full path with a bang prefix.

If you would like to include comment lines in your .projectile file, you can customize the variable `projectile-dirconfig-comment-prefix`. Assigning it a non-nil character value, e.g. `#`, will cause lines in the .projectile file starting with that character to be treated as comments instead of patterns.

### File-local project root definitions

If you want to override the projectile project root for a specific file, you can set the file-local variable `projectile-project-root`. This can be useful if you have files within one project that are related to a different project (for instance, Org files in one git repo that correspond to other projects).

## Storing project settings

From project to project, some things may differ even in the same language - coding styles, auto-completion sources, etc. If you need to set some variables according to the selected project, you can use a standard Emacs feature called Per-directory Local Variables. To use it you must create a file named `.dir-locals.el` (as specified by the constant `dir-locals-file`) inside the project directory. This file should contain something like this:

    ((nil . ((secret-ftp-password . "secret")
             (compile-command . "make target-x")
             (eval . (progn
                       (defun my-project-specific-function ()
                         ;; ...
                         )))))
     (c-mode . ((c-file-style . "BSD"))))

The top-level alist member referenced with the key `nil` applies to the entire project. A key with the name `eval` will evaluate its corresponding value. In the example above, this is used to create a function. It could also be used to e.g. add such a function to a key map.

Tip | You can also quickly visit or create the `dir-locals-file` with kbd:[s-p E] (kbd:[M-x] `projectile-edit-dir-locals` kbd:[RET]). 3rd party packages may use functions `projectile-add-dir-local-variable` and `projectile-delete-dir-local-variable` to store their settings.

Here are a few examples of how to use this feature with Projectile.

## Configuring Projectile’s Behavior

Projectile exposes many variables (via `defcustom`) which allow users to customize its behavior. Directory variables can be used to set these customizations on a per-project basis.

You could enable caching for a project in this way:

    ((nil . ((projectile-enable-caching . t))))

If one of your projects had a file that you wanted Projectile to ignore, you would customize Projectile by:

    ((nil . ((projectile-globally-ignored-files . ("MyBinaryFile")))))

If you wanted to wrap the git command that Projectile uses to list the files in you repository, you could do:

    ((nil . ((projectile-git-command . "/path/to/other/git ls-files -zco --exclude-standard"))))

If you want to use a different project name than how Projectile named your project, you could customize it with the following:

    ((nil . ((projectile-project-name . "your-project-name-here"))))

By default, compilation buffers are not writable, which allows you to e.g. press `g` to restart the last command. Setting `projectile-<cmd>-use-comint-mode` (where `<cmd>` is `configure`, `compile`, `test`, `install`, `package`, or `run`) to a non-nil value allows you to make projectile compilation buffers interactive, letting you e.g. test a command-line program with `projectile-run-project`.

    (setq projectile-comint-mode t)

## Project Buffers

Projectile offers a bunch of operations that are operating on the open buffers for some project (e.g. `projectile-kill-buffers`). One tricky part here are "special buffers" - basically buffers that are not backed by files (e.g. `*dired*`, `*scratch*` and so on). Projectile determines whether a special buffer belongs to a project simply by checking the `default-directory` for the special buffer, which admittedly might result in some weird results (e.g. if you’ve created a special buffer that’s not related to a project, while visiting a file belonging to the project).

That’s why Projectile has a couple of configuration options for dealing with project buffers - namely `projectile-globally-ignored-buffers` and `projectile-globally-ignored-modes`. Both of them take a list of strings or regular expressions that will be used to match against a buffer’s name or a buffer’s major mode.

Here are a couple of examples:

    ;; ignoring specific buffers by name
    (setq projectile-globally-ignored-buffers
      '("*scratch*"
        "*lsp-log*"))

    ;; ignoring buffers by their major mode
    (setq projectile-globally-ignored-modes
      '("erc-mode"
        "help-mode"
        "completion-list-mode"
        "Buffer-menu-mode"
        "gnus-.*-mode"
        "occur-mode"))

## Configure a Project’s Lifecycle Commands and Other Attributes

There are a few variables that are intended to be customized via `.dir-locals.el`.

- for configuration - `projectile-project-configure-cmd`

- for compilation - `projectile-project-compilation-cmd`

- for testing - `projectile-project-test-cmd`

- for installation - `projectile-project-install-cmd`

- for packaging - `projectile-project-package-cmd`

- for running - `projectile-project-run-cmd`

- for configuring the test prefix - `projectile-project-test-prefix`

- for configuring the test suffix - `projectile-project-test-suffix`

- for configuring the related-files-fn property - `projectile-project-related-files-fn`

- for configuring the src-dir property - `projectile-project-src-dir`

- for configuring the test-dir property - `projectile-project-test-dir`

When these variables have their default value of `nil`, Projectile runs the default command for the current project type. You can override this behavior by setting them to either a string to run an external command or an Emacs Lisp function:

    (setq projectile-test-cmd #'custom-test-function)

In addition caching of commands can be disabled by setting the variable `projectile-project-enable-cmd-caching` is to `nil`. This is useful for preset-based CMake projects.