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bug#20845: 25.0.50; bookmark.el, handling of fictitious `buffer' propert
bug#20845: 25.0.50; bookmark.el, handling of fictitious `buffer' property
Fri, 05 Jul 2019 09:46:31 -0400
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux)
> I'm looking into Emacs Bug#20845 which asks about the purpose of the
> "bookmark" property in bookmark.el.
I don't see any `bookmark` property, sorry.
>> Function `bookmark-default-handler' picks up and handles the property
>> (field) named `bookmark', if present.
>> I see nowhere else where this property is used, and nowhere where it is
>> set. And it is not documented.
Sounds like the description of leftover code. Usually it's either
because of an oversight or for backward compatibility purposes.
>> IOW, there is no notion or existence (AFAICT) of any bookmarks that
>> record a `buffer' property.
Which property are we talking about, `buffer` or `bookmark`?
>> * If the file is readable and is not visited then it visits the file
>> using `find-file-noselect'. Why?
I'll assume this question was the result of a temporary confusion on
Drew's part, since I think it's pretty obvious why we'd want to visit
the file here.
>> * Otherwise, if the buffer named by property `buffer' exists then the
>> default handler does nothing (no-op).
No: it selects that buffer as the current buffer.
> This handling was added in this commit:
> commit dbf8402bc76a775284905f09399b4d88ee0c03e5
> Author: Stefan Monnier <address@hidden>
> Date: Wed Feb 10 15:02:54 2010 -0500
> (bookmark-handle-bookmark): Catch the right error.
> (bookmark-default-handler): Accept new bookmark field `buffer'.
And it had been earlier removed by:
Author: Karl Fogel <address@hidden>
Date: Mon Oct 5 01:35:34 2009 +0000
so my commit re-instated support for it.
> But trying to find out why this was committed made me even more
> confused. I could find Stefan Monnier arguing against this change on
> two different occasions:
> 2010-01-25 - https://debbugs.gnu.org/cgi/bugreport.cgi?bug=5476#14
> 2010-01-26 - https://debbugs.gnu.org/cgi/bugreport.cgi?bug=5476#20
Good digging, thanks.
> I understand this was a long time ago, but if you still remember it,
> do you think you could help shed some light into the purpose of this
I can't remember why I accepted to install it, but these discussions
seem to indicate that the purpose for the patch was to preserve
compatibility with old bookmarks that don't use their own
> The suggestion given by Drew above is to remove it.
> Do you have an opinion about that?
Not really, no. But such "old-style" bookmarks might still be used by
third-party packages and might still appear in users's
~/.emacs.d/bookmarks, so if we want to remove support for it, maybe we
should try and do it gradually.
[...taking a second look...]
Oh, I see how/where it's used and it's definitely still used:
Info-bookmark-jump uses it (i.e. not in the stored bookmark object, but
in a transient object passed to bookmark-default-handler).
So maybe it should be documented in the docstring of
`bookmark-default-handler` for the benefit of other handlers.