Add projectile-uniquify-dirname-transform

CHANGELOG.md

@@ -21,6 +21,7 @@
 
 ### New features
 
+* Add `projectile-uniquify-dirname-transform`, a project-aware value for `uniquify-dirname-transform` that disambiguates same-named buffers using the project name. Mirrors `project.el`'s `project-uniquify-dirname-transform`.
 * [#2008](https://github.com/bbatsov/projectile/issues/2008): Add `projectile-remove-project-type` to unregister a project type. This is the supported way to stop Projectile auto-detecting a type; clearing its `marker-files` does not work (see the related bug fix below).
 * [#1936](https://github.com/bbatsov/projectile/issues/1936): Add `projectile-discard-root-cache` command to clear `projectile-project-root-cache` without touching other Projectile caches. Useful after creating or removing a project marker, since the existing `projectile-invalidate-cache` either also drops the file list cache or prompts for a project depending on context.
 * Warn once per session when `projectile-indexing-method' is `alien' but the project has a non-empty `.projectile' file, so users notice their dirconfig rules are being bypassed. Controlled by the new `projectile-warn-when-dirconfig-is-ignored' option.

doc/modules/ROOT/pages/projects.adoc

@@ -1200,6 +1200,21 @@ When you run `projectile-kill-buffers` (kbd:[s-p k]), the variable
 You can also set it to a custom predicate function that receives a buffer and
 returns non-nil if the buffer should be killed.
 
+=== Uniquifying buffer names by project
+
+When you open same-named files from different projects (say two `README.md`
+files), Emacs's `uniquify` library disambiguates the buffer names using parent
+directory components. Projectile can make that disambiguation use the project
+name instead, via `projectile-uniquify-dirname-transform`:
+
+[source,elisp]
+----
+(setq uniquify-dirname-transform #'projectile-uniquify-dirname-transform)
+----
+
+Outside of a project the directory is left untouched, so this is safe to set
+globally. This mirrors `project.el`'s `project-uniquify-dirname-transform`.
+
 == Configure a Project's Lifecycle Commands and Other Attributes
 
 There are a few variables that are intended to be customized via `.dir-locals.el`.

projectile.el

@@ -1684,6 +1684,25 @@ If PROJECT is not specified acts on the current project."
           "-"))))
 
 
+(defun projectile-uniquify-dirname-transform (dirname)
+  "Project-aware transform for `uniquify-dirname-transform'.
+When DIRNAME is inside a project, return a path with the project name
+spliced in, so buffers visiting same-named files in different projects
+get distinct, project-qualified names.  Outside a project DIRNAME is
+returned unchanged.
+
+To enable, set `uniquify-dirname-transform' to this function:
+
+    (setq uniquify-dirname-transform #\\='projectile-uniquify-dirname-transform)"
+  (if-let* ((root (projectile-project-root dirname)))
+      (expand-file-name
+       (file-name-concat
+        (file-name-directory root)
+        (projectile-project-name root)
+        (file-relative-name dirname root)))
+    dirname))
+
+
 ;;; Project indexing
 (defun projectile-get-project-directories (project-dir)
   "Get the list of PROJECT-DIR directories that are of interest to the user.

test/projectile-test.el

@@ -173,6 +173,17 @@ by `projectile-files-via-ext-command')."
     (let ((projectile-project-name-function (lambda (dir) dir)))
       (expect (projectile-project-name) :to-equal "current/project"))))
 
+(describe "projectile-uniquify-dirname-transform"
+  (it "splices the project name into a directory inside a project"
+    (spy-on 'projectile-project-root :and-return-value "/home/me/work/checkout-42/")
+    (spy-on 'projectile-project-name :and-return-value "myproject")
+    (expect (projectile-uniquify-dirname-transform "/home/me/work/checkout-42/src/")
+            :to-equal "/home/me/work/checkout-42/myproject/src/"))
+  (it "returns the directory unchanged outside a project"
+    (spy-on 'projectile-project-root :and-return-value nil)
+    (expect (projectile-uniquify-dirname-transform "/tmp/not-a-project/")
+            :to-equal "/tmp/not-a-project/")))
+
 (describe "projectile-prepend-project-name"
   (it "prepends the project name to its parameter"
     (spy-on 'projectile-project-name :and-return-value "project")