Add crux-transpose-windows for swapping the buffers between two windows

[dgtized]

This is copied directly from
https://www.emacswiki.org/emacs/TransposeWindows, and renamed to
crux-tranpose-windows. The wiki page mentions the original author as
Thomas Bellman. It does not appear to be published in any existing
package that I could find.

[bbatsov]

Looks good, just squash the two commits together. Adding a brief description of the difference with swap-windows would be useful as well I guess.

[dgtized]

Squashed the commits together. In terms of the difference between transpose and swap, swap only works for 2 open windows (and only for two, it errors out if there are more). To be honest, I'm not sure I can think of any case where swap-windows would be preferable to transpose. As far as I know, transpose is a superset of the functionality of swap-windows.

[bbatsov]

Btw, this should be cl-plusp. (or just (< 0 arg))

[bbatsov]

As far as I know, transpose is a superset of the functionality of swap-windows.

Probably we can mark the other function as obsolete and remove it down the road then.

[dgtized]

Fixed the cl-plusp issue, and documented the behavior on prefix arguments like 2 or -2.

The only part about swap-windows that I don't follow is why it calls set-window-start, I think that is actually unnecessary but not sure. I'm fine with marking it deprecated. I think you could even alias it to transpose windows, and no one would notice.

[bbatsov]

I think you could even alias it to transpose windows, and no one would notice.

Good idea. Alias it and remove it from the readme.

[dgtized]

Should that also be squashed in, a second commit or a different PR?

[bbatsov]

Second commit, same PR.

[bbatsov]

👍