Re: `save-excursion' defeated by `set-buffer'

[Uday Reddy <uDOTsDOTreddy@cs.bham.ac.uk>]

On 3/12/2011 10:42 AM, David Kastrup wrote:

> No, it isn't.  The likelilood that somebody uses `set-buffer' when he
> expects it not to change the current buffer is not exactly large.

Agreed.  But that is not the only case where the problems occur.  As 
explained in my message yesterday, there could be unprotected point 
movements deep inside function calls, which are unintentionally caught 
by the save-excursion at the outer level.  Ideally, those point 
movements should be protected where they occur, not by an unrelated an 
save-excursion sitting somewhere else.

Frankly, I think the warning message is quite fine.  save-excursion is 
trying to preserve the point (and mark), but only for the 
current-buffer.  set-buffer is changing the current-buffer and, so, the 
preservation of the point in the current-buffer is useless.

If one wants a completely plain warning message, it could be:

   "save-excursion has the effect of save-current-buffer"

It doesn't say very much, but nobody will presumably argue about it.

Cheers,
Uday