How to pass an argument from command to another command?

Question

From the package Neotree, I want to bind a key, that moves to the upper directory.

The upper directory is always on the top with .. (up a dir). So I go to the first line of the neotree buffer, and call neotree-enter to move to the upper directory. As a true Emacs'er, I figured out I need to modify it to my own preference.

So I created a function:

(defun neotree-go-to-upper-directory ()
    (interactive)
    (evil-goto-first-line)
    (neotree-enter)
)

(evil-define-key 'normal neotree-mode-map (kbd "h")'neotree-go-to-upper-directory)

After pressing h in NeoTree buffer, the cursor moves only to the top. But nothing happens. Then I call M-x neotree-enter, but still nothing happens.

When trace back into the source code of neotree-enter with C-h f then following the link, it's defined as:

(defun neotree-enter (&optional arg)
    "NeoTree typical open event.
    ARG are the same as `neo-open-file'."
    (interactive "P")
    (neo-buffer--execute arg 'neo-open-file 'neo-open-dir))

So I modified my function with adding the arguments as parameters:

(defun neotree-go-to-upper-directory (arg)
    (interactive "P")
    (evil-goto-first-line)
    (neo-open-dir arg)
)

Re-evaluated and calling neotree-go-to-upper-directory again inside Neotree buffer, but still nothing happens. Something I went wrong. But can anyone tell me where my code went wrong? It would be appreciated.

EDIT: For clarifity, as Lawlist suggested, I'm interested in a neotree solution. But some knowledge of Elisp would be also nice, because I'm struggling to understand why the function works for Neotree as well, and not in my case.

I got an working answer below:

(defun neotree-go-to-upper-directory ()
    "Go to the parent directory in the NeoTree buffer."
    (interactive)
    (neotree-dir ".."))

But unfortunately, this is not always working and I can't figure out what the cause of this is. For example, I enter a directory with neotree-enter and I want to call the function, then nothing will happen. It will be only working if I call neotree-change-root-directory then calling the function afterwards, it seems. And not when I do neotree-enter

Answer 1

Another possible solution:

(defun neotree-go-to-upper-directory ()
    (interactive)
    (evil-goto-first-line)
    (call-interactively #'neotree-enter))

(evil-define-key 'normal neotree-mode-map (kbd "h")'neotree-go-to-upper-directory)

call-interactively invokes the function exactly as it would have been with a keybinding, so it should work, in theory that is.

---

Okay, so the .. (up a dir) line is actually a button, which temporarily overrides RET while the point is over it. In that light, the solution is:

(defun neotree-go-to-upper-directory ()
    (interactive)
    (evil-goto-first-line)
    (call-interactively #'push-button))

(evil-define-key 'normal neotree-mode-map (kbd "h")'neotree-go-to-upper-directory)

Answer 2

From the package Neotree, I want to bind a key, that moves to the upper directory.

Here's what I came up with after a bit of exploration.

(defun neotree-go-to-upper-directory ()
  "Go to the parent directory in the NeoTree buffer."
  (interactive)
  (neotree-dir ".."))

Please edit the question to make it clear if this is what you were looking for (see @lawlists's comment above).