How to select string that is connected with dot on Emacs

Question

I want to select the whole word connected with dot. Is there any function in Emacs doing this.

Example:

123.456.[7]89

1. Cursor is on "7".

2. Apply "???function".

3. Region "123.456.789" is selected.

   [123.456.789]

Is there "???function" in Emacs?

Answer 1

Here's a solution:

(defun mark-whole-word ()
  (interactive)
  (let ((table (syntax-table)))
    (modify-syntax-entry ?. "w" table)
    (with-syntax-table table
      (backward-word)
      (set-mark (point))
      (forward-word))))

The key here is modifying the syntax. So if you replace ?. with ?- above, you can mark similarly 123-456-789.