save-check.el

The save-check package provides a simple means of checking for errors, by automatically running a linter when files are saved.

The idea is that this is a globally enabled package that does the right thing depending upon the mode of the file(s) you're working upon.

Implementation

Once enabled a global hook is added to after-save-hook, which will trigger the package and ensure future file-saves trigger the behaviour:

• The syntax check will be executed by executing an external process.
  • The command can be configured based upon the major-mode of the buffer.
• If the process exits with successful (zero) status-code, then nothing happens.
• If the process exits with a failure (non-zero) status-code
  • The STDOUT/STDERR of that process will be shown in a popup-buffer.
  • Pressing q will kill that notification.

Installation

The traditional way to install works just fine, save this file to a directory which is included upon your load-path, and then load it by adding the following to your init file:

;; Load the file
(require 'save-check)

;; Enable it
(global-save-check-mode 1)

If you're using use-package you can still download manually, and load/configure it like so:

(use-package save-check
  :defer 2
  :config
    (global-save-check-mode t))

If you have use-package and straight present then the following snippet will clone the repository at run-time, and allow you to use the package without any manual action:

(use-package save-check
  :straight (:host github :repo "skx/save-check.el")
  :config
    (global-save-check-mode t))

A similar approach use-package with vc should work on Emacs 30 out-of-the-box, again cloning the repository at run-time, and keeping things up to date automatically:

(use-package save-check
    :vc
      (:url "https://github.com/skx/save-check.el.git"
       :rev :newest)
    :config
      (global-save-check-mode t))

Configuration

The configuration of this package is mostly related to updating the save-check-config list.

There are several possible keys that can be set within the list-items:

• Mandatory arguments:
  • :mode - The name of the major-mode to operate within.
  • :exec - The process to execute to run the syntax-check.
    • %f will be replaced with the filename which was just saved.
    • %d will be replaced with the directory within which the file was just saved.
    • Note that :exec can be replaced with :lisp.
• Optional arguments:
  • :cond - An optional config that may be used to disable a check.
  • :eval - If this is present then the expression will be evaluated.

There are some other variables which can be set though:

• save-check-buffer-name
  • Configures the buffer-name of any failing results which are shown.
• save-check-show-eval
  • If :eval is used to execute a lisp expression on a particular mode then the output is discarded by default.
  • Set this value to a non-nil value to see it.