One tab per project, with unique names

This is a lightweight workspace management package that provides a thin layer between builtin packages project and tab-bar. The whole idea consists of creating a tab per opened project while ensuring unique names for the created tabs (when multiple opened projects have the same name).

This package is inspired by project-tab-groups which creates a "tab group" per project.

This package is available on MELPA.

(use-package otpp
  :straight t
  :after project
  :init
  ;; If you like to define some aliases for better user experience
  (defalias 'one-tab-per-project-mode 'otpp-mode)
  (defalias 'one-tab-per-project-override-mode 'otpp-override-mode)
  ;; Enable `otpp-mode` globally
  (otpp-mode 1)
  ;; If you want to advice the commands in `otpp-override-commands`
  ;; to be run in the current's tab (so, current project's) root directory
  (otpp-override-mode 1))

The usage is quite straightforward, there is no extra commands to learn to be able to use it. When otpp-mode global minor mode is enabled, you will have this:

• When you switch to a project project-switch-project (bound by default to C-x p p), otpp will create a tab with the project name.

• When you kill a project with all its buffers with project-kill-buffers, the tab is closed.

• Lets say you've switched to the project under /home/user/project1/backend/, otpp will create a tab named backend for this particular project. Now, you opened a second project under /home/user/project2/backend/, otpp will detect that the name of the project backend is the same as the previously opened one, but it have a different path. In this case, otpp will create a tab named backend[project2] and renames the previously opened tab to backend[project1]. This conflict resolution is provided by the otpp-uniq library.

• For some cases, you might need to attach a manually created tab (by tab-bar-new-tab) to an opened project so you have two tabs dedicated to the same project (with different windows layouts for example). In this case, you can call the command otpp-change-tab-root-dir and select the path of the project to attach to.

• When you use some commands to jump to a file (find-file, xref-find-definitions, etc.), you can end up with a buffer belonging to a different project (lets say B) but displayed in the current project's tab (A). In this case, you can call otpp-detach-buffer-to-tab to create a new tab dedicated to the buffer's project B. When the opened buffer is project-less (not part of a project), the command will signal a user error unless otpp-allow-detach-projectless-buffer is non-nil, in this case, otpp creates a new project-less tab for the buffer.

Consider this use case: supposing you are using otpp-mode and you've run project-switch-project to open the X project in a new X tab. Now you M-x find-file then you open the test.cpp file outside the current X project. Now, if you run project-find-file, you will be in one of these two situations:

1. If test.cpp is part of another project Y, the project-find-file will prompt you with a list of Ys files even though we are in the X tab.

2. If test.cpp isn't part of any project, project-find-file will prompt you to select a project first, then to select a file.

For this, otpp provides otpp-prefix (we recommend to bind it to some key, like C-x t P, using otpp-prefix from M-x can have some limitations). When you run otpp-prefix followed by C-x p f for example, you will be prompted for files in the current's tab project files even if you are visiting a file outside of the current project.

In my workflow, I would like to always restrict the commands like project-find-file and project-kill-buffers to the project bound to the current tab, even if I'm visiting a file which is not part of this project. If you like this behavior, you can enable the otpp-override-mode. This mode will advice all the commands defined in otpp-override-commands to be ran in the current's tab root directory (a.k.a., in the project bound to the current tab).

When otpp-override-mode is enabled, the otpp-prefix acts inversely. While all otpp-override-commands are restricted to the current's tab project by default, running a command with otpp-prefix will disable this behavior, which results of the next command to be run in the default-directory depending on the visited buffer.

This section is not exhaustive, it includes only the packages that I used before.

• project-tab-groups: This package provides a mode that enhances the Emacs built-in project to support keeping projects isolated in named tab groups. otpp is inspired by this package, but instead of setting the tab groups, otpp introduces a new attribute in the tab named otpp-root-dir where it stores the root directory of the project bound to the tab. This allows keeping the tabs updated in case another project with the same name (but a different path) is opened.

• tabspaces: This package provide workspace management with tab-bar and with an integration with project. Contrary to otpp and project-tab-groups, tabspaces don't create tabs automatically, you need to call specific commands like tabspaces-open-or-create-project-and-workspace. Also, tabspaces behavior isn't predictable when you open several projects with the same directory name.

When non-nil, preserve the current rootless tab when switching projects.

Bury the current buffer when killed but it is opened in another tab.

When non-nil, this modifies the behavior of kill-buffer when killing the current buffer. If the current buffer is opened in another tab, we bury it instead of killing it. This only affects the current buffer, when we explicitly select another buffer to kill, otpp assumes that we have a good reason to kill it.

Whether to reconnect a disconnected tab when switching to it.

When set to a function's symbol, that function will be called with the switched-to project's root directory as its single argument.

When non-nil, show the project dispatch menu instead.

Whether to strictly obey local variables.

Set a nil (default value) to only respect the local variables when they are defined in the project's root (the dir-locals-file is located in the project's root).

Set to a function that takes DIR, PROJECT-ROOT and DIR-LOCALS-ROOT as arguments in this order, see the function otpp-project-name. The function should return non-nil to take the local variables into account.

This can be useful when the project include sub-projects (a Git repository with sub-modules, a Git repository with other Git repos inside, a Repo workspace, etc).

List of functions to call after changing the otpp-root-dir of a tab. This hook is run at the end of the function otpp-change-tab-root-dir. The current tab is supplied as an argument.

Derive project name from a directory.

This function receives a directory and return the project name for the project that includes this path.

Allow detaching a buffer to a new tab even if it is not part of a project. This can also be set to a function that receives the buffer, and return non-nil if we should allow the tab creation.

A list of commands to be advised in otpp-override-mode. These commands will be run with default-directory set the to current's tab directory.

The default tab name to use when the last otpp tab is killed.

Get the root directory set to the TAB, default to the current tab.

Get the project name from DIR. This function extracts the project root. Then, it tries to find a dir-locals-file file that can be applied to files inside the directory DIR. When found, the local variables are read if any of these conditions is correct:

• otpp-strictly-obey-dir-locals is set to a function, and calling it returns non-nil (we pass to this function the DIR, the project root and the directory containing the dir-locals-file).
• otpp-strictly-obey-dir-locals is a not a function and it is non-nil.
• The dir-locals-file file is stored in the project root, a.k.a., the project root is the same as the dir-locals-file directory. Then, this function checks in this order:

1. If the local variable otpp-project-name is set locally in the dir-locals-file, use it as project name.
2. Same with the local variable project-vc-name.
3. Return the directory name of the project's root. When DIR isn't part of any project, returns nil.

Create or switch to the tab corresponding to the project of BUFFER. When called with the a prefix, it asks for the buffer.

Change the otpp-root-dir attribute to DIR. If if the absolute TAB-NUMBER is provided, set it, otherwise, set the current tab. When DIR is empty or nil, delete it from the tab.

Return a list of tabs that have DIR as otpp-root-dir attribute.

Select or create the tab with root directory DIR. Returns non-nil if a new tab was created, and nil otherwise.

Run the next command in the tab's root directory (or not!). The actual behavior depends on otpp-override-mode. For instance, when you execute M-x otpp-prefix followed by C-x p f, if the otpp-override-mode is enabled, this will run the project-find-file command in the default-directory, otherwise, it will bind the default-directory to the current's tab directory before executing project-find-file.