RE: arrow keys vs. C-f/b/n/p

[Drew Adams]

Very clear post, which helps me understand. Thank you.

> Now please note an important detail: in a L2R paragraph, C-f generally
> moves cursor _to_the_right_, even though it could sometimes change
> direction and move to the left, when we are traversing R2L text
> embedded into a L2R paragraph.  Similarly, in a R2L paragraph, C-f
> generally moves cursor _to_the_left_.  In the important special case,
> when L2R paragraphs include only L2R text and R2L paragraphs include
> only R2L text, cursor motion with C-f is strictly to the right
> resp. to the left.

That sounds reasonable.

> This is the reason

What is the reason?

> why the <right> arrow key moves like C-f in a L2R
> paragraph, and why the <left> arrow key moves like C-f in a R2L
> paragraph.  (And similarly with C-b.)

FWIW, I don't see a supporting argument for why the arrows should have different
behavior from C-f/C-b.

> It is so that Emacs behaves as expected

Well, there's the reason, but what is it? What is "expected" of the arrow keys,
that means they should act differently from C-f/C-b?

You made it clear that we are, in all cases, talking only about logical order
(which you defined as buffer order, beginning to end). And both arrows and
C-f/C-b follow the logical order (a-z, in your example).

It is still a question why the paragraph direction should reverse which arrow
key moves forward vs backward (in logical order). You might have a good reason
for that, but so far I haven't seen it. You've only said that this is "expected"
of the arrows.

Don't get me wrong - I don't really care. I'm just pointing out that you haven't
really given a good reason for this, beyond some hand-waving ("expected").

> in a purely R2L paragraph containing only R2L text.  Any
> other operation would be confusingly counter-intuitive: the <right>
> key would actually move cursor _to_the_left_!

How is that different for C-f/C-b? Should one pair be counter-intuitive but not
the other? Why?

> Again, we are talking _only_ about _logical-order_movement_!

Great.

Again, thanks for a clear post. It really was helpful. 

And as I say, I don't really care one way or the other for myself (I'll probably
always use L2R text). But it might help if you do give some rationale for why
arrows, but not C-f/C-b, should behave "intuitively".