Re: Get current buffer name from command line?

[Marcin Borkowski <mbork@wmi.amu.edu.pl>]

Dnia 2014-08-13, o godz. 17:40:07
Stefan Monnier <monnier@iro.umontreal.ca> napisał(a):

> > 1. So what exactly is "current-buffer"?  Or, more precisely, why
> > (progn (kill-buffer) (current-buffer))
> > didn't work?
> 
> current-buffer is something that changes all the time for
> internal reasons.  E.g. while processing the request coming from
> emacsclient, the current-buffer will be temporarily changed to the
> *server* buffer.  That has no influence on display.
> 
> It's simply that most operations that touch a buffer do it on the
> current-buffer, so if you want to look at a buffer's content, or
> change it, or consult some of its variables, the way you typically do
> it is by temporarily changing current-buffer.
> 
> The same holds for manipulating windows, which is why selected-window
> may not always return what you think (as a user) as "the selected
> window" (e.g. it may get temporarily changed by process-filter
> handling a subprocess's output).

I see.

> > 2. Why "more often"?  Is it possible that it won't?  To be more
> > precise on my requirements: I thought about writing a script (to be
> > put into cron) which would gather data on what I'm doing at various
> > times so that I can measure time spent on different activities.
> > Since most of my computer time is spent in Emacs, this would be an
> > important part of it.  From the docstring of selected-window, it
> > seems to be exactly what I'm looking for.  Still, the words "more
> > often" made me a bit suspicious;).
> 
> I think "emacsclient -e '(window-buffer (selected-window))'" will work
> fine for your use case, but if you want to take idle time into
> account, you might like to use a post-command-hook which sets a
> global var to the "current time after last command" at which point
> you could also set a global var to "the selected-window after last
> command" which should be more reliable.

OK, now I get it.  Thanks for taking the time to explain this to me!

>         Stefan

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Adam Mickiewicz University