加载了Exec-Path时，Emacs无法找到Python.exe（Windows 8.1）

Question

I've had quite a bit of success using Emacs with R and Org-mode, and was wanting to branch that out into Python as well. I initially set up my environmental path (through Windows) and exec-path (through the .emacs file) to point to the folder containing my Python binary. Unfortunately, when I try to evaluate a command/start the interpreter in Python-Mode, I get the following error:

python-shell-calculate-exec-path: Wrong type argument: listp, "~/folder/foo"

where "~/folder/foo" was the last item on my exec-path list. When I removed exec-path from my .emacs file, the inferior Python process loaded fine. Obviously, this is not a real solution if I want to use anything else on the path. I've tried to search for documentation of this problem, but was less than successful.

I am using GNU Emacs 24.5.1 (x86_64-w64-mingw32) on a Windows 8.1 laptop (Lenovo, if that matters). The failing mode is the basic "Python" and not "Python-Mode" proper, which doesn't seem to want to load. The python executable is properly configured in my environmental variables setup (it works in Windows command prompt), and the inferior python process works only so long as I do not have my exec-path loaded. The relevant code is:

(setq exec-path (append exec-path ' "~/folder/foo"
                                  ' "~/folder/foo"))

Answer 1

It's a bit odd, but it seems that explicitly setting the exec-path in this way was what was causing the problem. After a little bit of fiddling around with alternative means of setting the exec-path (to avoid the listp problem) I found that using:

(add-to-list 'load-path "~/folder/foo")
(add-to-list 'load-path "~/folder/foo")

instead of setq exec-path worked just fine in terms of letting me use my binaries and in letting me get to Python, too. Solution is posted in case anyone else has a similar issue (students and self-taught users like myself especially).

Note: I did not add the location of my Python executable to my .emacs file in any way, just the environmental variable Path in Windows. This was sufficient for Emacs to find the executable.