Ethereal-dev: RE: [Ethereal-dev] Deactivate "Apply" button if the display filte ris not valid?
|From: Guy Harris
|
|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.)
Hence I conclude that an empty filter (consisting of white space only)
should be considered as cleared (which was my *personal* thought on this
too).
Should we implement this check and the deactivation of the "Apply" button
and stuff, then we can add a short note to the documentation that you can
still fool Ethereal by editing white space to force a full dissection.
Should we want to avoid this, then we need to:
1. Store the last applied display filter *program*
2. Compare the new filter program with the stored one
from step 1 whenever the display filter changes
3. Decide to make "Apply" visible (and to decide that
the display filter may be applied) whenever the
filter programs differ.
Regards,
Olivier
