bug#40213: what-cursor-position could tell the meaning of marks too!

bug#40213: what-cursor-position could tell the meaning of marks too!

[積丹尼 Dan Jacobson]

It's one of those days. You see those marks "+", "A+" in the Summary
Buffer,

  + 1 200306 16|      |台電資訊處            :RE: Fartsworth Affair
    1 200324 39|      |John (John Lewddis)   :[Maniphest] [Closed] T99999: Can not do any thing
 A+ 1 200324 24|      |cclin                 :Re: Ants in pants

but are too lazy to look up what they mean (in (info "(gnus) Other
Marks") etc.).


No worry, C-u C-x = (what-cursor-position) will tell you:

 There are text properties here:
   face                 gnus-summary-high-unread
   gnus-number          31074

Ahhh... alas it could tell you more!

And, on (info "(gnus) Other Marks") it could say "You can also just use
C-u C-x = to figure out what any mark mentioned here means, without
needing to read this page."

P.S., regarding "+", that info page says

   • When using the Gnus agent (*note Agent Basics::), articles may be
     downloaded for unplugged (offline) viewing.  If you are using the
     ‘%O’ spec, these articles get the ‘+’ mark in that spec.  (The
     variable ‘gnus-downloaded-mark’ controls which character to use.)

Well I am not using Gnus agent, and my .gnus.el has no %O or even O in
it. Thus it would be great if what-cursor-position told me what "+" meant.

Gnus v5.13
GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.11)
 of 2019-09-23, modified by Debian

bug#40213: what-cursor-position could tell the meaning of marks too!

[Lars Ingebrigtsen]

積丹尼 Dan Jacobson <jidanni@jidanni.org> writes:

> It's one of those days. You see those marks "+", "A+" in the Summary
> Buffer,
>
>   + 1 200306 16|      |台電資訊處            :RE: Fartsworth Affair
>     1 200324 39|      |John (John Lewddis)   :[Maniphest] [Closed] T99999: Can not do any thing
>  A+ 1 200324 24|      |cclin                 :Re: Ants in pants
>
> but are too lazy to look up what they mean (in (info "(gnus) Other
> Marks") etc.).
>
> No worry, C-u C-x = (what-cursor-position) will tell you:
>
>  There are text properties here:
>    face                 gnus-summary-high-unread
>    gnus-number          31074
>
> Ahhh... alas it could tell you more!

I think that's pretty much impossible -- there's no infrastructure in
Emacs to have it tell you what a random character in a generated buffer
means.  And adding a bunch of text properties everywhere just in case
you wonder would be impractically slow.

So I'm closing this bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#40213: what-cursor-position could tell the meaning of marks too!

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > > No worry, C-u C-x = (what-cursor-position) will tell you:
  > >
  > >  There are text properties here:
  > >    face                 gnus-summary-high-unread
  > >    gnus-number          31074
  > >
  > > Ahhh... alas it could tell you more!

  > I think that's pretty much impossible -- there's no infrastructure in
  > Emacs to have it tell you what a random character in a generated buffer
  > means.  And adding a bunch of text properties everywhere just in case
  > you wonder would be impractically slow.

Here's a way that is trivially easy to implement, and won't be slow.
Invent a new text property: 'significance'.  If the character
has that property, its value should be a string which explains
what the character "means" in that particular case.

If a mode puts some sort of special marker in a buffer, it can
put that text property on it.


This is trivial to implement because it requires no code.
C-u C-x = will display the text property anyway ;-}.


-- 
Dr Richard Stallman
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

bug#40213: what-cursor-position could tell the meaning of marks too!

[Lars Ingebrigtsen]

Richard Stallman <rms@gnu.org> writes:

> Here's a way that is trivially easy to implement, and won't be slow.
> Invent a new text property: 'significance'.  If the character
> has that property, its value should be a string which explains
> what the character "means" in that particular case.
>
> If a mode puts some sort of special marker in a buffer, it can
> put that text property on it.

But that would be slow.  The use case here is all the different
characters used as markers in a Gnus Summary buffer -- and there may be
tens of thousands of them.  Making generation of these buffers (which is
already slow) even slower, just to make it possible to these characters
for their meaning, would be a disservice to the users.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#40213: what-cursor-position could tell the meaning of marks too!

[Juri Linkov]

>> If a mode puts some sort of special marker in a buffer, it can
>> put that text property on it.
>
> But that would be slow.  The use case here is all the different
> characters used as markers in a Gnus Summary buffer -- and there may be
> tens of thousands of them.  Making generation of these buffers (which is
> already slow) even slower, just to make it possible to these characters
> for their meaning, would be a disservice to the users.

Maybe then 'describe-char' could check if the mode's symbol has a special property
with a function name, and output a string returned from that function, e.g.

  (put 'gnus-summary-mode 'describe-char 'gnus-summary-mode-describe-char)

Then 'describe-char' called in a gnus-summary-mode buffer will get the
function from its property, and 'gnus-summary-mode-describe-char' will
introspect its buffer and report information about the character
displayed at the given position and its meaning.

bug#40213: what-cursor-position could tell the meaning of marks too!

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > But that would be slow.  The use case here is all the different
  > characters used as markers in a Gnus Summary buffer -- and there may be
  > tens of thousands of them.  Making generation of these buffers (which is
  > already slow) even slower, just to make it possible to these characters
  > for their meaning, would be a disservice to the users.

That might perhaps be slow, but my guess is it won't
take enough time to notice.  Would you like to try it and see?

-- 
Dr Richard Stallman
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

bug#40213: what-cursor-position could tell the meaning of marks too!

[Lars Ingebrigtsen]

Juri Linkov <juri@linkov.net> writes:

> Maybe then 'describe-char' could check if the mode's symbol has a
> special property
> with a function name, and output a string returned from that function, e.g.

There's nothing special about the character per se -- a "+" in a subject
has no meaning.  It only has a meaning as a marking character.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#40213: what-cursor-position could tell the meaning of marks too!

[Lars Ingebrigtsen]

Richard Stallman <rms@gnu.org> writes:

> That might perhaps be slow, but my guess is it won't
> take enough time to notice.  Would you like to try it and see?

Nope.  It's already too slow.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no