[Gllug] Open Ports

tet at accucard.com tet at accucard.com
Mon Jan 28 16:14:23 UTC 2002


>> Bleugh! Sorry, pet hate of mine. Config files should never contain
>> negative options. This should be "enable = no". Poor interface design.
>
>I see no logical reason for this.  The normal reason to write up a 
>service in  xinetd.conf is to enable it - to disable it simply don't 
>include it.  The default is for a service to be enabled, so it makes 
>sense to add a disable line for the exceptions rather than having to add 
>an enable line to all the others.

The whole reason for avoiding negative options is to increase clarity,
by avoiding double negatives. Thus, even if it's optional, using
"enable = no" is still better than "disable = yes".

xinetd is far from the only guilty party here. The Linux kernel itself
does the same. "Disable NAGLE algorithm?" should instead be "Enable
NAGLE algorithm?" and should default to yes, for example.

The worst offender for this, though, was a Windows 3.11 app I once saw
(I can't even remember it's name now), which had a check box labelled
"don't disable foobar". If that was unchecked, then you have a triple
negative to try and express what you want to do. True, we're not
talking about anything that extreme here, but the same principle
applies.

Tet

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