Re: `looking-back' strange warning

[Michael Heerdegen]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> You can pass (point-min) for the limit if that's what you want.
> Making it optional Encourages people to think that looking-at is just
> like looking-back, with the same performance characteristic, whereas
> making it mandatory encourages people to put a reasonable limit and
> hence avoid pathological behavior at the end of large buffers.

My two cents: Even if you specify an optimal limit, `looking-back' can
still be unnecessarily slow.  For example,

   (looking-back "xy" 2)

is much slower than

    (and (> (point) 2)
         (save-excursion
           (goto-char (- (point) 2))
           (looking-at "xy")))

where "xy" stands for any plain string.


Michael.