[Semediawiki-user] Type:Boolean and Boolean printouts

[Markus <ma...@ai...>]

Hi all,

SMW just got one new and one old feature (coming with the next release=20
candidate) which I think are worth pointing out:

(1) Type:Boolean works again. It mostly does what it did in SMW0.7: you ent=
er=20
values by saying 1 or 0, or one of the true- or false-words defined for you=
r=20
language. You can customise query printouts in various ways now (using #ask=
=20
syntax):

?boolproperty   =20
   default printout with main labels of the language

?boolproperty#true,false
   use "true" and "false" as labels for the two values

?boolproperty#x
   use 'X' for true and nothing for false, useful for making cross tables

(in <ask> syntax these would be [[boolproperty::*]],=20
[[boolproperty::*true,false]], and [[boolproperty::*x]])

BUT, before you start using Booleans all over your wiki, let me point out=20
another feature:

(2) "Boolean printouts" for categories are now possible. This is a kind of=
=20
printout statement for queries that will show you for each result whether o=
r=20
not it belongs to a given category or not. Consider the following example=20
query:

{{#ask:[[Category:Event]] |
  ?title =3D Name|
  ?Category:Conference|
  ?Category:Workshop|
  limit=3D50
}}

The query shows 50 elements of Category:Event with various printouts. The=20
important parts are the ones of the form "?Category:Conference". So far the=
re=20
was only "?Property" (print all property values) and "?Category" (print *al=
l*=20
categories). Now "?Category:Conference" checks whether a result is in=20
Category:Conference and returns a Boolean value based on this. The default=
=20
output style for this is "X" which is most easy to read in output tables, b=
ut=20
you can also customise it just like Type:Boolean (e.g. one could=20
write "?Category:Conference=3Dis conference,no conference" to get those two=
=20
labels associated).

See http://ontoworld.org/wiki/Upcoming_events#List_of_upcoming_events for a=
n=20
example printout of this kind.

Note that this feature does not work with the old <ask>-style syntax. #ask =
is=20
just better for such extensions (and for many other things).



So you can actually use normal categories instead of properties of=20
Type:Boolean in many cases. My suggestion is to do that, since categories=20
integrate better with the article layout, and since they are also used by=20
many other MW features and extensions (CategoryTree, SemanticDrilldown,=20
etc.). The cases where Type:Boolean properties are still useful are (a) whe=
n=20
you want to distinguish between "true", "false", and "unspecified"=20
(categories really only have "true" and "false-or-unspecified"), or when yo=
u=20
have so many property values on one page that categories would not be easy =
to=20
read or maintain anymore. But do as you like.

Cheers,

Markus

P.S. Printouts of the form "?property::value" with the obvious meaning are=
=20
also planned, but need some more internal changes to work.

=2D-=20
Markus Kr=F6tzsch
Institut AIFB, Univers=E4t Karlsruhe (TH), 76128 Karlsruhe
phone +49 (0)721 608 7362        fax +49 (0)721 608 5998
ma...@ai...        www  http://korrekt.org