CODEWITHSUNDEEP
elisp
quemester
quemester

Reputation: 33

post-self-insert-hook throws "Invalid Function"

(defun foo (aa)
  (interactive)
  (progn
    (setq aa '(+ aa 1))
  ))

(defun bar ()
  (interactive)
  (setq b 6)
  (add-hook 'post-self-insert-hook (foo b)))

Instead of incrementing b, elisp throws an error: Invalid function: 7. It does take b as an argument, but only when its equal to 6, it stops working after incrementing. Why? The problem occures with b being equal to any number, it always prints message like Invalid function:b+1.

Upvotes: 0

Views: 142

Answers (2)

phils
phils

Reputation: 73314

As sds says, there are a lot of problems with that code.

(defun foo (aa)
  (interactive)
  (progn
    (setq aa '(+ aa 1))
  ))

This function briefly sets the variable aa (which is its own argument and never seen by anything outside of the function) to the literal quoted form (+ aa 1). It also returns that same value. Here aa is the symbol aa and nothing more.

(defun bar ()
  (interactive)
  (setq b 6)
  (add-hook 'post-self-insert-hook (foo b)))

(foo b) is not a function, and therefore adding it to a hook will result in an error.

(lambda () (foo b)) is a function which calls (foo b)

elisp throws an error: Invalid function: 7.

Not with the code you've shown, it won't. Clearly you're evaluating a version in which you haven't quoted (+ aa 1) in which case (foo 6) will actually return 7 and hence you're trying to do this:

(add-hook 'post-self-insert-hook 7)

Upvotes: 0

sds
sds

Reputation: 60044

Right now there are far too many problems with your code to address them one by one.

You need to start with learning how Lisp works.

In Emacs, hit C-h i then click on Emacs Lisp Intro: (eintr), then keep reading.

Upvotes: 1

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