Subject: Re: bug#9871: `query-replace' and friends break text properties

From: Štěpán Němec <[email-masked]>
Date: Mon, 19 Aug 2019 10:43:49 +0200

On Sun, 18 Aug 2019 17:03:28 -0700
Lars Ingebrigtsen wrote:

> I guess the question becomes -- what text properties should be in the
> result?
>
> If you have
>
> (with-temp-buffer
>   (insert (propertize "hel" 'face 'bold))
>   (insert (propertize "lo" 'face 'underline))
>   (goto-char (point-min))
>   (replace-regexp "ell" "yes, well")
>   (buffer-string))
>
> should "yes, well" be in bold or underline?  Or a mix?  I don't really
> think there's any solution here that will satisfy anybody.
                                                    ^^^^^^^
I assume you meant "everybody".

> But I guess it would make some sense to view this as "delete the text,
> and then pretend we're inserting text as if by `self-insert-command'",
> which would make the new text bold here.

Yes it would. I also think that the straightforward case where all the
text has the same value for a property will be much more frequent than
your contrived example (note my property wasn't even visible at all; in
case of font-locking for example I'd expect the result to get
refontified as usual anyway).

> I don't know...  all solutions here seem kinda ad hoc, so perhaps the
> current behaviour is the least surprising.  Any opinions?

I definitely don't consider it the least surprising, but I guess you're
rather asking for the opinion of other people.

On Sun, 18 Aug 2019 17:57:18 -0700 (PDT)
Drew Adams wrote:

[...]

> If a user specifies replacement text that has
> text properties then it should be used as is:
> its properties should remain when it takes the
> place of text in the buffer.

[...]

Sure. For the yanking (i.e., interactive) case there's also
`yank-handled-properties' and `yank-excluded-properties'.

-- 
Štěpán