bug#17718: 24.4.50; doc string of `display-buffer-alist'

bug#17718: 24.4.50; doc string of `display-buffer-alist'

[Drew Adams]

Not comprehensible - to me at least.

Consider just "ALIST" in the description.  It is described nowhere.
Worse: it is used to describe other things, so that they too are
effectively undefined  and incomprehensible.

What is the cdr of ACTION?  It's ALIST, whatever that is (presumably an
alist of some kind).  What is done with that ALIST?  No idea.

What is the car of ACTION?  It's a function that accepts a buffer and an
alist "of the same form as ALIST".  Huh?  And what form is that?  ALIST
is not described anywhere.

Then you get "`display-buffer' scans this alist..."  Which alist?  There
are at least 3 different alists mentioned in this doc string:

* The alist that is the value of the user option.
* The alist that is the cdr of ACTION.
* The alist that is the argument to FUNCTION, which is the car of
  ACTION.

And the doc says nothing about the alist that gets passed to FUNCTION.
Even if you can somehow figure out the form of FUNCTION's second arg,
you have no idea what buffer and what alist are passed to it.  How,
based on that, you might decide on a (FUNCTION . ALIST) to use is a
mystery.

And the description of this option in the Elisp manual is even less
specific, and does not clear things up.

I'm sorry, but the doc for `display-buffer-alist' (and `display-buffer')
is still gobbledygook, even after repeated requests by users to please
clear it up.  It's a wonder that anyone can make sense of this.

In GNU Emacs 24.4.50.1 (i686-pc-mingw32)
 of 2014-06-01 on ODIEONE
Bzr revision: 117212 michael.albinus@gmx.de-20140601104945-g88x0mwrxorz302h
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/snapshot/trunk
 --enable-checking=yes,glyphs 'CFLAGS=-O0 -g3'
 LDFLAGS=-Lc:/Devel/emacs/lib 'CPPFLAGS=-DGC_MCHECK=1
 -Ic:/Devel/emacs/include''

bug#17718: 24.4.50; doc string of `display-buffer-alist'

[Drew Adams]

Same problem for `display-buffer-base-action':

 User-specified default action for `display-buffer'.
 It should be a cons cell (FUNCTION . ALIST), where FUNCTION is a
 function or a list of functions.  Each function should accept two
 arguments: a buffer to display and an alist similar to ALIST.
 See `display-buffer' for details.

Again, ALIST is not described, and neither is the alist that is
the second arg to FUNCTION.  And neither is FUNCTION (what it is
for, what it does with its args, etc.)

And no, just punting to "See `display-buffer' for details" does
not help.  None of this is described in its doc.  The
`display-buffer' doc sting just punts, itself, saying that it
"combines" a bunch of stuff, including `display-buffer-base-action'.

bug#17718: 24.4.50; doc string of `display-buffer-alist'

[Lars Ingebrigtsen]

Drew Adams <drew.adams@oracle.com> writes:

> Not comprehensible - to me at least.

(I'm going through old bug reports that unfortunately got no response at
the time.)

The doc string of this variable (and `display-buffer') has been much
improved since this bug report was filed, so I'm closing this bug report.

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