required vs optional

James Bonfield jkb at
Thu Feb 8 12:09:58 UTC 2001

On Wed, Feb 07, 2001 at 06:18:20PM +0000, Peter Rice wrote:
> > req          opt                greyed out
> > Y            N                  N
> > Y            Y                  N
> > N            N                  N
> > N            Y                  Y
> Swap those last two. opt:y means it can be useful opt:n means you can change
> it if you dare.

This still leaves me confused. Swapping the last two gives:

req          opt                greyed out
Y            N                  N
Y            Y                  N
N            N                  Y
N            Y                  N

The defaults are both N, so not specifying either req or opt indicates a
greyed-out option, which cannot be true surely?

Can you please spell out for me exactly when we can be sure (during
processing, not just at the time of producing help) when we know a question
will be ignored (ie changing it's value has no effect)?

> > Anyway, only when it's optional and not required should I grey them out.
> > However as optional defaults to N only places where opt:Y is explicitly stated
> > will I ever grey out paramaters, which unfortunately includes all those
> > graphics options (eg this is syco):
> Some misunderstanding of 'required' perhaps?

And optional too - I considered optional:N to indicate a mandatory question,
but that's the purpose of required.

> Can you just generate the tcl variable you need? If only req or opt will be
> used you can just pick the value of whichever one is being set. Spare 'N'
> settings can be safely ignored, as they are the default anyway.

What if both req and opt are used (ignoring any opt:N and req:N settings)?
embossdata looks to be the only one that uses both (but I didn't also check
for param). Filename is defined as opt:Y req:$(fetch). I suppose as it's opt:Y 
then it may be useful and so should never be displayed as greyed-out.
(I have been wondering about an "optional" tab so that the option values are
automatically put into a separate area of the dialogue.)


James Bonfield (jkb at   Tel: 01223 402499   Fax: 01223 213556
Medical Research Council - Laboratory of Molecular Biology,
Hills Road, Cambridge, CB2 2QH, England.
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