make-overlay and endpoints

Marcus Harnisch writes: AFAIK, Emacs doesn't give you the choice of removing the overlay from the buffer. By default, and it doesn't delete the extent, it detaches it. (I don't think Emacs implements detached overlays.) If you want the extent to remain in the buffer, set the detachable property to nil. If you're using the overlay library from fsf-compat, this might be a bug in overlay emulation. You may misunderstand the nature of character positions in Emacsen, I suspect. They are conceptually *between* characters in the buffer, so there are two sides, before and after. Thus inserting a character *at* a position has unambiguous semantics. This is also reflected in the character access functions: to examine a single character you can use `char-after' or `char-before', but there is no `char-at' function. Extents, on the other hand, *can* be "at" a position. In particular, a zero-length extent is "at" exactly one position (unless detached, in which case it is nowhere). `delete-char' is an historical misnomer; it really should be `delete-forward-char' (the reverse function is `delete-backward-char', or maybe more easily understood would be `delete-char-{forward,backward}'). I'm not sure why those particular semantics for deletion of zero-length extents were chosen, and the documentation is hardly clear to me. I don't understand what the practical problem you're experiencing is, so I doubt all this theoretical discussion is of much help (unless maybe it will result in a bug report on fsf-compat). Sorry about that, and feel free to follow up. _______________________________________________ XEmacs-Beta mailing list XEmacs-Beta(a)xemacs.org http://lists.xemacs.org/mailman/listinfo/xemacs-beta