Re: Turning on savehist-mode by default

[Eli Zaretskii <eliz@gnu.org>]

> From: Thanos Apollo <public@thanosapollo.org>
> Date: Tue, 28 Nov 2023 13:04:41 +0200
> 
> > savehist-mode is a useful mode which is turned on by many Emacs
> > users. [1] It matches the default behavior of programs like bash and
> > vim, which save command history by default.  I suggest that we should
> > find some way to enable savehist by default.
> >
> 
> What is the recommended way for package authors to disable
> savehist-mode?
> 
> If savehist-mode is enabled by default, it is advisable to also consider
> a simple way to disable it for a specific package mode.
> 
> for example I'm using emacs to answer a MCQ, such as:
> 
> Q:Which one of the following statements concerning the
> ability of acidosis to precipitate a crisis in sickle cell
> anemia is correct?
> 
> ```emacs-lisp
> (completing-read "Answer: "
> '("Fetal blood has a higher affinity for oxygen than does
> adult blood because Hb F has a decreased affinity for
> 2,3-BPG."
> "Purified Hb F (stripped of 2,3-BPG) has a higher affin-
> ity for oxygen than does purified Hb A."
> "The globin chain composition of Hb F is α2δ2."))
> ```
> Saving the latest and usually correct answer defeats the purpose of an MCQ.
> 
> One workaround for this is to set minibuffer-history to nil, although it
> is unclear whether this is advised, even with a let statement.

You could instead bind history-add-new-input to nil around calls to
completing-read.