[emboss-dev] Empty value in list

Sebastien Moretti Sebastien.Moretti at unil.ch
Fri Apr 4 14:06:10 UTC 2008

> Hi Sebastian,
>> How can I make an empty choice in list values attribute ?
>> Something like
>>     values: " , a, t"
>>         delimiter: ", "
>> with 'a', 't' and '' (or ' ') as choices.
> You need something for the user to choose, so you have to use a name
> like "none".
> EMBOSS tests the user's input by comparing it to all the list values and
> finding one that is unambiguous. For example, typing "a" is accepted if
> only one value starts with "a...".
> Typing nothing (just hitting return when prompted) is EMBOSS's way to
> accept the default value. There will be no way for the user to specify
> an empty choice.
> Can you give a little more information about why you want an empty 
> choice in a list?
> regards,
> Peter

My application has different output modifiers which are parameters in fact:

normal: ''
full:	'-a'
short:	'-t -'

There is maybe a more efficient way to deal with this, e.g. with toggle.
But list are more simple.

Thus, if I use this
	default: " "
	values: "-a, -t -"
         delimiter: ", "

I get what I want but it is not very 'clean'.

Sébastien Moretti
SIB, Quartier Sorge - Genopode
CH-1015 Lausanne, Switzerland
Tel.: +41 (21) 692 4056/4221

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