[Guy Harris <guy@xxxxxxxxxxxx>]

On Tue, Feb 10, 2004 at 07:33:52AM +0100, Ulf Lamping wrote:
> Olivier Biot wrote:
> >I agree. However: should valid empty filters (such as a single space)
> >be cleared or considered cleared?
> >
> If the user wants a single space, he should be able to use it, so I 
> would tend to see this as a non emtpy filter.
> You will get a lot of difficult questions otherwise: is a tab also a 
> whitespace, do we want to remove this and that too,
> why is character xyz not removed. This behaviour will be hard to 
> describe for our users.

Note that a display filter containing only white space compiles to a
null filter program, just as an empty string does.

As such, I see a filter with a single space as an *empty* filter.  (I
also consider the fact that no filter program is generated to be a
feature, not a bug.)