critique: my-first-function

critique: my-first-function

[James K. Lowden]

Although I've been using emacs for years, today was the first time I
set out to write a substantial (to me) function from first principles.
Below is what I came up with.  I wonder if anyone has a suggestion or
opinion on how it might have been done better, differently, or more in
the spirit of the emacs zeitgeist?  

(defun open-tall-frames ()
  "Open two tall frames."
  (interactive)
  (let ( (frame-parameters 
	  '((width . 80)
	    (height . 60)
	    (minibuffer . t)
	    (window-system . x)))
	 (frame1 (make-frame frame-parameters))
	 (frame2 (make-frame frame-parameters))
	 )
  (set-frame-position frame1 -1 0)
  (set-frame-position frame2 (- (frame-pixel-width frame1)) 0)
))

--jkl

Re: critique: my-first-function

[Stefan Monnier]

> 	 (frame1 (make-frame frame-parameters))
> 	 (frame2 (make-frame frame-parameters))
> 	 )
>   (set-frame-position frame1 -1 0)
>   (set-frame-position frame2 (- (frame-pixel-width frame1)) 0)

You can specify the frame's initial position directly when calling
`make-frame`, using parameters like `top` and `left`.


        Stefan

Re: critique: my-first-function

[Emanuel Berg]

"James K. Lowden" <jklowden@speakeasy.net>
writes:

> (defun open-tall-frames ()
>   "Open two tall frames."
>   (interactive)
>   (let ( (frame-parameters 
> 	  '((width . 80)
> 	    (height . 60)
> 	    (minibuffer . t)
> 	    (window-system . x)))
> 	 (frame1 (make-frame frame-parameters))
> 	 (frame2 (make-frame frame-parameters))
> 	 )
>   (set-frame-position frame1 -1 0)
>   (set-frame-position frame2 (- (frame-pixel-width frame1)) 0)
> ))

`let' should be `let*' since "frame-parameters"
are used inside the same `let'.

Some more subjective views:

As for style, I think you can align the
data items (lines 5-8).

Instead of "frame1" "frame2", name them after
some property.

And, on line 13, there is a computation, which
I would name and put in the `let' clause as
well. So you set up all data there, and then
only have execution below the `let' - makes it
look good.

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Re: critique: my-first-function

[James K. Lowden]

On Mon, 13 Jun 2016 03:08:47 +0200
Emanuel Berg <embe8573@student.uu.se> wrote:

My thanks to both you and Stefan.  

> `let' should be `let*' since "frame-parameters"
> are used inside the same `let'.

It's a good thing you mentioned that!  The next morning, I had to
restart emacs (because ssh mumble something timeout) and my function
failed.  It had worked the day before because 

>   (let ( (frame-parameters 

frame-parameters happened to have been defined globally during
testing.  Adding the "*" fixed it instantly.  

Is the "*" a convention of some kind that I should be aware of?  

> Instead of "frame1" "frame2", name them after
> some property.

Well, one day the whole thing will be a recursive call over a list of
coordinates.  The frames don't deserve names, but I couldn't see my way
to creating the list.  

Thanks again.  

--jkl

RE: critique: my-first-function

[Drew Adams]

> Is the "*" a convention of some kind that I should be aware of?

Sort of.  Some functions that are similar to other functions use
the same base name as the latter, but with a `*' suffix.  This is
more prominent in some lisps.

For example, Common Lisp has `do' and `do*'.  `do*' is to `do' as
`let*' is to `let': the bindings of the `*' versions are evaluated
sequentially.