I use Emacs 26.1 and would like to compare two files word-by-word. Clicking "Tools -> Compare (Ediff) -> Windows Word-by-word..." allows only to compare the visible parts of two buffers, not the whole buffers. This seems to be intended behavior as per my other question. The response there contains a working solution for comparing two complete buffers. There seem to be no issues with performance.

How can this be used to compare two files? It would be nice if a menu option could be added as well: "Tools -> Compare (Ediff) -> Files Word-by-word...".

  • 2
    Visit the files, then use the answer to your other question?
    – Drew
    Commented Nov 25, 2018 at 14:41

1 Answer 1


You can copy the following Elisp snippet into your init file.

Disclaimer: The code comes without any guaranty. It references internal functions of ediff. So use it with caution.

The newly defined command ediff-files-wordwise just runs ediff-files with two main modifications:

  • (ediff-word-mode . word-mode) is added to the SETUP-PARAMETERS of ediff-setup.
  • The buffer contents of buf-A and buf-B is wordified and saved in temporary files that are used for the diff-program.

    (eval-after-load "ediff"
         `(defun ediff-files-wordwise (file-A file-B &optional startup-hooks)
            ,(concat (documentation 'ediff-files)
                     "\nComparison is done wordwise.")
            ,(interactive-form 'ediff-files)
            (cl-letf* ((oldfun (symbol-function 'ediff-setup))
                       ((symbol-function 'ediff-setup)
                        (lambda (buffer-A file-A buffer-B file-B buffer-C file-C startup-hooks setup-parameters &optional merge-buffer-file)
                          (let* ((tmp-buffer (get-buffer-create ediff-tmp-buffer)))
                            (with-current-buffer buffer-A
                              (ediff-wordify (point-min) (point-max) buffer-A tmp-buffer))
                            (setq file-A (ediff-make-temp-file tmp-buffer "regA"))
                            (with-current-buffer buffer-B
                              (ediff-wordify (point-min) (point-max) buffer-B tmp-buffer))
                            (setq file-B (ediff-make-temp-file tmp-buffer "regB"))
                            (setq overl-A (with-current-buffer buffer-A
                                            (ediff-make-bullet-proof-overlay (point-min) (point-max) buffer-A))
                                  overl-B (with-current-buffer buffer-B
                                            (ediff-make-bullet-proof-overlay (point-min) (point-max) buffer-B)))
                            (funcall oldfun
                                     buffer-A file-A buffer-B file-B buffer-C file-C startup-hooks
                                      (list (cons 'ediff-word-mode 'word-mode)
                                            (cons 'ediff-narrow-bounds (list overl-A overl-B)))
              (ediff-files file-A file-B startup-hooks))))
        (require 'easymenu)
         '("Compare (Ediff)")
         ["Two Files Word-by-word..." ediff-files-wordwise t]
         "Two Buffers...")))

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