Post Script the above is not tested. On Friday, July 26, 2019 at 2:20:31 PM UTC+10, TonyM wrote: > > I just wanted to share this code pattern I just discovered for Handling > the emptyMessage condition in the ListWidget Body. > > Sometimes the way we write Filters the only way to proceed is to use the > emptyMessage to deal with the null case. > > If the Null case response requires multiple lines of wiki text it gets a > little messy > > \define macrodef() > If condition not met > \end > > > <$list filter="condition" emptyMessage=<<macrodef>> > > If Condition met > </$list> > The macro def must be at the top and it is removed from the list widget > > > OR > <$list filter="condition" emptyMessage=""" > > If condition not met > """> > If Condition met > </$list> > This makes me nervous :) > > So I developed this method/pattern > <$list filter="[is[current]tagging[]] ~[[::false]]" variable=result> > <$list filter="[<result>prefix[::]]" variable=case> > Do this if <<case>> > </$list> > <$list filter="[<result>!prefix[::]]" variable=case> > Process tiddler "<<case>>"<br> > </$list> > </$list> > Using the unlikely tiddler title "::false" to flag the empty set condition. > In this case the null *case* is executed once and the "no null case" as > many times as needed. > > *And did I mention "case"?* > > This structure also allows us to build a CASE structure with a default > behaviour. > > That is if a variable or field contains one of a number different values, > and you wish to respond differently for each > > <$list filter="[<casevariable>] ~[[::false]]" variable=case> > <$list filter="[<case>prefix[::false]]" variable=case> > Do this if no case value > </$list> > <$list filter="[<case>prefix[caseone]]" variable=case> > Process "caseone"<br> > </$list> > <$list filter="[<case>prefix[casetwo]]" variable=case> > Process "casetwo"<br> > </$list> > <$list filter="[<case>prefix[casethree]]" variable=case> > Process "casethree"<br> > </$list> > <!-- Even this --> > <$list filter="[<case>prefix[casetwo]] [<case>prefix[casethree]]" > variable=case> > Process "casetwo" and "casethree"<br> > </$list> > </$list> > > With the mathematics operators > > More will be possible? > > Regards > Tony > > > > >
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