Re: Misery with undo. Help, please!

[Stefan Monnier]

>> > [*] Actually, it inserts an extra, spurious, nil too, or I've badly
>> > misunderstood something.  This seems to be a bug in the macro `push'.
>> No, it isn't.  The command loop automatically inserts an undo boundary.
>> You should use ielm for your experiments.
> Ah, thanks!  How come I didn't know about ielm?

Indeed, how come?

> The problem, with a buffer-undo-list of (nil 6 nil ......) is that
> primitive-undo piles nothing onto it, merely moving point to 6.
> buffer-undo-list thus remains unaltered after C-_.  This is a bug.

In itself maybe it's not a bug (tho it should probably record some
other point-motion entry), but it probably introduces problem
w.r.t. undo-equiv-table.  Can someone try and figure out why C-_ doesn't
record a point-motion entry on the buffer-undo-list?


        Stefan