Re: Recentish C-s M-y change

[Gregory Heytings]

> After some reflection, here's what I think the point is.
>
> isearch-mode-map is not like a prefix key's map. A control character 
> which is undefined in isearch-mode-map is not a vacant space, not a 
> place you can put some nice new feature and nobody will mind.
>
> The undefined control character is a useful convenience feature, which 
> people use.

Thank you, now I understand what you mean.  I don't use that feature 
myself, but it's there and I can understand that people (and in particular 
you) find it convenient.

> Except that with many control characters defined, it is hard to remember 
> which ones are defined -- hard to be confident that a given control 
> character is one that will exit the search for you.

Yes, but the only newly defined control character which makes Emacs in 
2020 different from Emacs in 1985 is C-m / RET, bound to isearch-exit 
around 1990.  Previously C-m / RET terminated isearch and inserted a 
newline; now C-m / RET only terminates isearch.

You defined C-g, C-q, C-r, C-s, C-w and C-y in 1985 (or perhaps earlier).

C-h has also been bound in the meantime, but you can still exit isearch 
with C-h as you would have done it in 1985, for instance with C-h C-g, or 
C-h f.  IIUC the only difference is that C-h k now describes the key in 
isearch-mode-map instead of the key in global-map.

Likewise, C-x has been bound in the meantime, to allow C-x 8 RET, but you 
can still exit isearch with C-x as you would have done in 1985, for 
instance with C-x C-f or C-x b.

Likewise, C-u has been bound in the meantime, to allow arguments to 
subcommands, but again you can still exit isearch with C-u as you would 
have done in 1985, for instance with C-u C-b or C-u C-n.