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Proper use of function form


From: Tim Johnson
Subject: Proper use of function form
Date: Sun, 26 Apr 2020 15:27:15 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1

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

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."

Can be found at https://endlessparentheses.com/get-in-the-habit-of-using-sharp-quote.html

fuurther text there describes the special 'function form for which the sharp-quote is a shorthand.

Suppose we are processing a sexp of alternating strings and symbols:

(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)) ?

I note that help for 'function states a preference for using it with function objects, but says nothing about processing a list. Hence I am lobbying wiser heads than mine for opinions before I implement something that might cause subtle problems down the road.

Emacs is GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, X toolkit, Xaw scroll bars)
on ubuntu 16.04

Thanks

-- f
Tim
tj49.com



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