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Re: Proper use of function form


From: Emanuel Berg
Subject: Re: Proper use of function form
Date: Mon, 27 Apr 2020 10:06:20 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux)

Tim Johnson wrote:

> Here is a key definition:
>
> (define-key jinja2-mode-map (kbd "C-c i") #'jinja2-insert-var)
>
> As I understand it, the sharp-quote (#') tells the
> compiler that jinja2-insert-var is meant to be
> a function

Yes, that's what happens. I don't know what the
byte-compiler does with that information tho, maybe it
is just a matter of it being able to warn you if that
function doesn't exist, since with the hash-quote, it
knows where to look specifically...

But there is also the advantage of you being able to see
that something is, or supposed to be, a function.

Perhaps font-lock could also be told to give it
a special color, e.g. `font-lock-function-name-face', if
desired - to increase seeing/reduce reading
even further.

> The following quotation:
>
> "it is always good practice to sharp quote every
> symbol that is the name of a function, whether it's
> going into a mapcar, an apply, a funcall, or
> anything else."

Well, that's what I do and it always worked. But if you
seek a more scientific documentation and practical
HOWTO, surely this is documented in the official
manual(s)?

> (setq my-keypairs '("h" my-h-func "g" my-g-func "f" my-f-func))
>
> and using iteration to *programmatically* call
> define-key for multiple key definitions as in
>
> (define-key mymap                          ;; add to keymap
>     (kbd (concat ldr (nth ndx mylist)))    ;; sequence as in "g"
>     (nth (+ ndx 1) mylist))                ;;
> command as in my-g-func
>
> The form above is indeed a snippet from a defun that
> I have used for years
>
> Would it be better to change (nth (+ ndx 1) mylist) to
> (function (nth (+ ndx 1) mylist)) ?

But even if that had worked all the advantages mentioned
so far would be lost, right?

Maybe you could initially instead of the quote use the
backquote/comma, or `list', with hash-quote?

-- 
underground experts united
http://user.it.uu.se/~embe8573
https://dataswamp.org/~incal




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