Re: switch-to-buffer-other-frame fails to pop-up window

[Mark T. Kennedy]

martin rudalics wrote:
>  > 1) contrast the behavior of 'c-x 5 b' with 'c-x 4 b'.  'c-x 4 b' always 
> forces the creation of two
>  > different windows, even when displaying the same buffer.  'c-x 5 b' does 
> not always force the
>  > creation of two frames.
>
> When you have two windows on the selected frame, w1 is the selected
> window and w2 the other one, w2 shows buffer b, and w1 does not show
> buffer b, C-x 4 b will simply switch to w2.  Thus C-x 4 b and C-x 5 b
> behave very similarly.

but two windows exist already in your "c-x 4 b" scenario.  and if only one 
window
existed, it would be created.  the "other window" invariant is maintained 
regardless
of whether it has to create a new window or just switch to an existing one.

but "c-x 5 b" behaves like "c-x 4 b" in the single-frame, two-window
scenario you described above.  it does *not* cause a second frame to
be created.  it just switches to w2 without creating a new frame.  the
"other frame" invariant is *not* maintained.

>
>  > 2) one might guess that 'switch-to-buffer-other-frame' is essentially a 
> wrapper that
>  > sets 'pop-up-frames' to 't' and then calls display-buffer (and it is).
>  > while the behavior of display-buffer is meticulously documented, the 
> observed
>  > behavior clashes with the documentation for 'pop-up-frames'.  now if it 
> were
>  > called "maybe-pop-up-frames" or "frequently-pop-up-frames", i wouldn't feel
>  > so bad, but... :-).
>
> The documentation of `pop-up-frames' in the Elisp manual appears
> correct:
>
>   -- User Option: pop-up-frames
>       This variable controls whether `display-buffer' makes new frames.
>       If it is non-`nil', `display-buffer' looks for an existing window
>       already displaying the desired buffer, on any visible frame.  If
>       it finds one, it returns that window.  Otherwise it makes a new
>       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>       frame.  The variables `pop-up-windows' and
>       `split-height-threshold' do not matter if `pop-up-frames' is
>       non-`nil'.
>
> The doc-strings of `pop-up-frames' and `switch-to-buffer-other-frame'
> are misleading.  The former says "*Non-nil means `display-buffer' should
> make a separate frame." but fails to explain the semantics of "should".
> The latter tells "Switch to buffer buffer in another frame." which is
> just silly IMHO.

mea culpa.  i did not think to look in the elisp doc.

>
>  > so i'm requesting (not demanding :-) a change in behavior.
>  >
>  > what use case would clash with a change like this?
>
> I don't know, maybe there is one.  We could try to provide a third value
> for `pop-up-frames': If it's 'force `display-buffer' would _always_ try
> to display the buffer in a new frame regardless of how many times it is
> already displayed.  What do you think?
>
>

that would certainly provide a work-around and make me happy.

but i'm still curious why the intent of pop-up-frames is overridden by
display-buffer.  there has to be a reason lurking somewhere?

/mark

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