Re: emacs-25 2460cfa: * doc/lispref/lists.texi (Association Lists): Document 'alist-get'.

[Michael Heerdegen]

John Wiegley <address@hidden> writes:


> The old way:
>
>     GET: (cdr (assq key my-alist))
>     SET: (setcdr (assq key my-alist) new-value)
>
> The new hotness:
>
>     GET: (alist-get key my-alist)
>     SET: (setf (alist-get key my-alist) new-value)

That's only one half of the truth: Your two SETs are different if KEY is
not yet present in MY-ALIST.  "The old way" doesn't work in that case,
the new one does.  It replaces a complete

  (if (assq ...)
    (setcdr ... ...)
   (push ... ...))


Michael.