Commit 9227b5ce authored by Thien-Thi Nguyen's avatar Thien-Thi Nguyen
Browse files

last-chance: new utility lib for dangling deterrence

* admin/last-chance.el: New file.
parent e2767bd0
;;; last-chance.el --- dangling deterrence -*- lexical-binding: t; -*-
;; Copyright (C) 2000-2016 Free Software Foundation, Inc.
;; Author: Thien-Thi Nguyen <>
;; Maintainer:
;; Keywords: maint
;; Package: emacs
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <>.
;;; Commentary:
;; Late 2016. In a recent build, the date in a ChangeLog file
;; is not fontified. Turns out the face ‘change-log-date-face’
;; was declared obsolete since 22.1 and removed 2016-06-23.
;; (compile "git show c430f7e23fc2c22f251ace4254e37dea1452dfc3")
;; This library provides a command ‘last-chance’, which is a small
;; combination of "git grep" and some regexp filtering. For example,
;; if point is on the symbol ‘change-log-date-face’ in the form:
;; (define-obsolete-face-alias 'change-log-date-face ...)
;; then:
;; M-x last-chance RET
;; will show you any references to ‘change-log-date-face’ in the
;; *.el files in a new buffer (in Grep mode). Hopefully you see
;; only the obsolete declaration and can proceed w/ its removal.
;; If not, please DTRT and refrain from the removal until those
;; references are properly transitioned.
;; [Insert "nobody reads ChangeLog files" lament, here. --ttn]
;;; Code:
(require 'grep)
(require 'thingatpt)
(defvar last-chance-grep-command "git grep -n -H -F -e"
"Command that ends in \"-e\" to do the \"git grep\".
This should include -n, -H, -F.")
(defvar last-chance-uninteresting-regexps
;; Add more ‘flush-lines’ args here.
"List of regexps that match uninteresting \"git grep\" hits.")
(defvar-local last-chance-symbol nil
"Symbol set by ‘last-chance’ for ‘last-chance-cleanup’ to DTRT.")
(defun last-chance-cleanup (buffer status)
"Filter lines in BUFFER; append STATUS and count of removed lines.
If BUFFER is not seem to be one created by ‘last-chance’, do nothing.
This function is intended to be added to ‘compilation-finish-functions’."
(let ((name (buffer-local-value 'last-chance-symbol buffer))
bef aft)
(when name
(with-current-buffer buffer
(setq bef (count-lines (point-min) (point-max)))
(goto-char (point-min))
(search-forward last-chance-grep-command)
(forward-line 1)
(let ((inhibit-read-only t))
(dolist (re last-chance-uninteresting-regexps)
(flush-lines re))
(keep-lines (format "\\_<%s\\_>" name)))
(setq aft (count-lines (point-min) (point-max)))
(goto-char (point-max))
(insert (format "(status: %s, lines removed: %d)"
(car (split-string status "\n"))
(- bef aft)))))))
(defun last-chance (symbol)
"Grep the repo for SYMBOL, filtering the hits.
This uses ‘last-chance-grep-command’ to do the grep and the
regexps in ‘last-chance-uninteresting-regexps’ to filter the hits.
Grepping is recursive starting under the dir that ‘vc-root-dir’
finds (or the default directory if ‘vc-root-dir’ finds nothing).
Output goes to the *grep* buffer.
Interactively, Emacs queries for a symbol,
defaulting to the one at point."
(interactive (list (read (let ((one (symbol-at-point)))
(when one
(setq one (symbol-name one)))
"Symbol: " obarray
nil nil
one nil one)))))
(let ((default-directory (or (vc-root-dir)
(grep (format "%s %s"
(setf (buffer-local-value 'last-chance-symbol
(car compilation-in-progress)))
(add-to-list 'compilation-finish-functions
(provide 'last-chance)
;;; last-chance.el ends here
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