kill-region deletes entire buffer content instead of selected text

Question

In emacs, i have a small text selected as shown in the picture.

When i do eval-buffer, i like the kill-region to remove only the highlighted text. But this code empties the buffer.

;;this is a simple comment....
(message "%s" (region-active-p))
(kill-region (region-beginning) (region-end))

Doesn't region-end retun the selection region's end?

Answer 1

As the comments suggest, eval-buffer manipulates the position of point, so that by the time you call kill-region, region-beginning and region-end are no longer what they were when you started. The position of point is 'preserved', as @ColinBell points out, but in this case that means that point is moved during eval-buffer, and then restored to it's original value when it's done. So from the user's perspective, it doesn't change.

eval-buffer really doesn't make sense for code that is intended to modify the buffer itself. There's almost certainly a more appropriate way to do what you want.