Re: Why does Gnus article-moving act like a fetch of new news?

[Karl Fogel <kfogel@red-bean.com>]

On 09 Apr 2021, Eric Abrahamsen wrote:
> I think an argument could be made that if the DONT-SCAN optional 
> argument is non-nil, we should also skip running the two 
> get-new-news hooks. But let's see what Lars says. 

You mean the second argument to 
`gnus-group-get-new-news-this-group'?

The doc string is somewhat confusing on that argument:

  | gnus-group-get-new-news-this-group is an interactive compiled 
  | Lisp function in ‘gnus-group.el’.  |  | 
  (gnus-group-get-new-news-this-group &optional N DONT-SCAN) |  | 
  Check for newly arrived news in the current group (and the N-1 
  next groups).  | The difference between N and the number of 
  newsgroup checked is returned.  | If N is negative, this group 
  and the N-1 previous groups will be checked.  | If DONT-SCAN is 
  non-nil, scan non-activated groups as well. 

In other words, the meaning of "DONT-SCAN" seems to be: scan!  One 
can see how a person might be confused by this :-).

According to the "Terminology" section in the Gnus manual, 
"activating" a group means this:

  | The act of asking the server for info on a group and computing 
  the | number of unread articles is called “activating the 
  group”.  | Un-activated groups are listed with ‘*’ in the group 
  buffer. 

Thus I don't understand why moving an article to a group should 
unconditionally "activate" that group in the first place.  I can 
see how moving an *unread* article to a group might activate that 
group?  But the code in `gnus-summary-move-article' doesn't have 
such a conditional.

And even if we leave aside the question of why we unconditionally 
activate the destination group, it's still not clear why 
activating a group should imply getting new news for that group. 
Or, to put it another way: why is the way to activate a group to 
get new news for it?  These just seem like two very different 
things.

I realize you may not know the answers either, and that we may 
need Lars or someone with a similar level of knowledge.  I'm just 
trying to line up some useful questions.  Gnus is a very, very 
complex code base, I have learned through several dives in its 
coastal waters.

Best regards,
-Karl