Re: How to change overlay arrow position silently?

[Juri Linkov]

>> Its docstring says it can be used non-interactively:
>
>>   When called from Lisp code, the optional argument BUFFER
>>   ==========================
>>   specifies a buffer to switch to.
>
> It seems like even this `buffer' argument is very much an "interactive"
> feature since it causes the buffer to be displayed, which may cause new
> windows/frames to be created.
>
> Makes me wonder: does any code use this `buffer' argument?  My guess is
> that it's only used by things like the command-line-arg processing
> (and/or the emacs-server).  We had better make it more clear: do not use
> it from Elisp unless you know what you're doing (i.e. add it to
> byte-compile-interactive-only-functions).

I can't find any code that uses this `buffer' argument, but there are
more than 150 places in Emacs that call this `goto-line' function.
So we can't easily prohibit using it non-interactively.  But I think
there is no harm when using non-interactively.  A similar function
"goto-char" has interactive/non-interactive duality with no problem.

The only problem with "goto-line" is that it sets the mark and prints
the message "Mark set".  Using a new argument `interactivep' will allow
the programmer to decide where to do this.  When a command is just
a wrapper around the `goto-line' (like the command `View-goto-line')
then it should call `goto-line' with interactivep=t.

-- 
Juri Linkov
http://www.jurta.org/emacs/