dired-default-directory-alist is a variable defined in `dired-x.el'.
Its value is

((dired-mode if (fboundp 'dired-current-directory) (dired-current-directory) default-directory))

  • This variable is obsolete since 24.1;
    this feature is due to be removed.
  • This variable may be risky if used as a file-local variable.

Alist of major modes and their opinion on `default-directory'.
Each element has the form (MAJOR . EXPRESSION).
The function `dired-default-directory' evaluates EXPRESSION to
determine a default directory.