Re: Framework extending window functions for Follow Mode (etc.).

[Alan Mackenzie]

Hello, Emacs.

On Thu, Nov 05, 2015 at 07:29:05PM +0000, Alan Mackenzie wrote:
> Partly out of a need to nail down bug #17453, partly out of a need to
> make it easier for arbitrary libraries to work with Follow Mode, partly
> at the suggestion of Eli, I now propose the following.

> The six functions window-start, window-end, set-window-start, recenter,
> pos-visible-in-window-p, and move-to-window-line-function will acquire
> an extra optional parameter GROUP.  The notion is that "this call is
> interested in groups of windows, not just single ones".

> Each of these functions will get an associated variable, e.g.
> "window-start-function".  The function will call the value of that
> variable instead of doing its normal actions, when GROUP is non-nil.
> Typically, the `window-start-function' will recursively call
> window-start (on some window) to perform its operation.

Now renamed to "window-start-group-function", at John's suggestion.

> window-start-function, and friends, will be set by Follow Mode in its
> initialisation, and unset when it is disabled.

I've now updated the requisite two pages in Elisp.

This suggestion doesn't seem to have sparked off too much debate.  Can I
take it that people are generally happy about it?  In that case, I will
commit the change.

[ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).