Re: comint.el: EMACS environment variable

[Chong Yidong]

Markus Triska <address@hidden> writes:

> Miles Bader writes:
>
>> Why would they care what it's value is though?  I suspect it's just as
>> common to simply check for the variable's existance, not its value.
>
> Yes, that's also common (at least those programs aren't broken by the
> change). Other programs checking for "t": tcsh, Maude, zsh. For easy
> optional backwards compatibility, what do you think about making the
> new behaviour depend on a variable like "emacs-environment-variable"
> with possible values 'path (use path; default) and t (old behaviour)?

This patch implements this (modulo the requisite documentation
changes).

*** emacs/lisp/comint.el.~1.348.~       2006-09-28 16:31:39.000000000 -0400
--- emacs/lisp/comint.el        2006-11-07 13:26:49.000000000 -0500
***************
*** 363,368 ****
--- 363,376 ----
  
  This is a good thing to set in mode hooks.")
  
+ ;;;###autoload
+ (defvar comint-subshell-envvar 'path
+   "Default value of the EMACS environment variable in subshells.
+ Any existing value for the EMACS environment variable overrides this.
+ A value of `path' means the absolute file name of the Emacs executable.
+ Otherwise, this should be a string that specifies the value of the
+ environment variable.")
+ 
  (defvar comint-input-filter
    (function (lambda (str) (not (string-match "\\`\\s *\\'" str))))
    "Predicate for filtering additions to input history.
***************
*** 769,775 ****
            (list "TERM=emacs"
                  (format "TERMCAP=emacs:co#%d:tc=unknown:" (window-width))))
          (unless (getenv "EMACS")
!           (list (concat "EMACS=" invocation-directory invocation-name)))
          process-environment))
        (default-directory
          (if (file-accessible-directory-p default-directory)
--- 777,789 ----
            (list "TERM=emacs"
                  (format "TERMCAP=emacs:co#%d:tc=unknown:" (window-width))))
          (unless (getenv "EMACS")
!           (list (concat "EMACS="
!                         (cond ((eq comint-subshell-envvar 'path)
!                                (concat invocation-directory
!                                        invocation-name))
!                               ((stringp comint-subshell-envvar)
!                                comint-subshell-envvar)
!                               (t (error "Invalid subshell envvar"))))))
          process-environment))
        (default-directory
          (if (file-accessible-directory-p default-directory)
*** emacs/lisp/progmodes/compile.el.~1.409.~    2006-09-24 17:59:32.000000000 
-0400
--- emacs/lisp/progmodes/compile.el     2006-11-07 13:26:54.000000000 -0500
***************
*** 1069,1075 ****
              ;; Set the EMACS variable, but
              ;; don't override users' setting of $EMACS.
              (unless (getenv "EMACS")
!               (list (concat "EMACS=" invocation-directory invocation-name)))
              (copy-sequence process-environment))))
        (set (make-local-variable 'compilation-arguments)
             (list command mode name-function highlight-regexp))
--- 1069,1081 ----
              ;; Set the EMACS variable, but
              ;; don't override users' setting of $EMACS.
              (unless (getenv "EMACS")
!               (list (concat "EMACS="
!                             (cond ((eq comint-subshell-envvar 'path)
!                                    (concat invocation-directory
!                                            invocation-name))
!                                   ((stringp comint-subshell-envvar)
!                                    comint-subshell-envvar)
!                                   (t (error "Invalid subshell envvar"))))))
              (copy-sequence process-environment))))
        (set (make-local-variable 'compilation-arguments)
             (list command mode name-function highlight-regexp))