What's the difference between `eval-expression` and `:Eval `?
reddit / emacs

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hkjels · 2022-04-26 07:10

I prefer a clean frame for Emacs, so I've set `frame-title-format` to
be empty, but whenever I resize the frame, the size of the frame is
appended to the frame title. If I `:Eval (setq frame-title-format "
")` the frame-title is cleared. I've checked and that should be the
equivalent of `eval-expression`, but doing `(eval-expression '(setq
frame-title-format " "))` in a hook does nothing. Using `setq`
directly also does nothing. So what's the difference between `eval-
expression` and `:Eval`? Or, what's the difference between running a
command immediately and running a command via hooks?

I've also tried `(set 'frame-title-format " ")` thinking it's a scope-
issue, but no luck

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7890yuiop · 2022-04-26 08:13

What do you mean by `:Eval` ?

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hkjels · 2022-04-26 08:16

What is bound to `M-:`

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7890yuiop · 2022-04-26 08:36

That's `eval-expression`

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7890yuiop · 2022-04-26 08:44

> in a hook

Which hook?

> Using setq directly

Where?  When?

You're omitting most of the information needed to answer your
questions.

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hkjels · 2022-04-26 08:47

Doesn't matter which one. I've been using `(add-hook 'focus-in-hook
'elan-remove-title)` just to test it. And I can see that the hook is
run cause I just placed a `message` in there.

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hkjels · 2022-04-26 09:01

```
(defun elan-remove-title ()
  (set 'frame-title-format " "))

(add-hook 'window-size-change-functions 'elan-remove-title)
```

Something along these lines is what I want and expected to work

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7890yuiop · 2022-04-26 09:14

That's an abnormal hook -- your function has to accept its
(documented) argument.

`M-x elisp-index-search RET abnormal hook`

> Doesn't matter which one.

Evidentially it does.

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hkjels · 2022-04-26 09:47

I have verified that the hook is being run by outputting a message, so
that's not the issue.

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hkjels · 2022-04-26 10:09

OK, from now reading a bunch of docs. This should really have been the
proper way AFAICT.

```
(defun elan-remove-title (frame)
  (push '(title . " ") frame))

(add-hook 'window-size-change-functions 'elan-remove-title)
```

Although, it does however not work. I tried adding `run-at-time` to
see if there's some race-condition of the text being set and that's
not the case either.
So, I'm back to there being a difference between manually running
`:Eval` and using `set` or whatnot.


I've also noticed, that this only occurs when I use a third-party app
to scale the Emacs frame. If I use the mouse to scale the frame,
`sets-default` suffice.

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ieure · 2022-04-26 16:55

Guessing this is some evil-mode thing.

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7890yuiop · 2022-04-26 19:05

> I've also noticed, that this only occurs when I use a third-party
app to scale the Emacs frame.

I don't know what this means.  Details are super important when asking
people for help, and you have a tendency to make vague references to
things but not actually specify what they are.

I probably can't help with any "third-party app" in any case; but I'm
confident that you have a better chance of someone else being able to
if you provide actual details.

My best suggestion is that you provide a recipe to reproduce the
problem -- all the ingredients, and step-by-step actions in detail.