Re: Image cache

[Juri Linkov <juri@jurta.org>]

>> 	* image-mode.el (image-toggle-display): Use file name if possible,
>> 	instead of unnecessarily allocating a (possibly huge) lisp string.
>
> Ugh.  Two simple solutions come to mind: (i) revert my change, or (ii)
> clear the image cache on each call to image-toggle-display.  I don't
> know which is worse, performance-wise -- any suggestions?

Your change also has another undesirable effect: if doesn't handle the
situation when Emacs can't read the image.  It visits the image file in
text mode but thinks that it is in image mode (i.e. hides the cursor and
prints a wrong message in the echo area).  Before your change handling this
situation in image-mode.el was not nice either: with debug-on-error=t
it signalled an error "Cannot determine image type", and with
debug-on-error=nil this error was not reported at all.

-- 
Juri Linkov
http://www.jurta.org/emacs/