The query is treated just like a pattern. ? indicates whether the query should be materialised or not. In general if you aren't sure, then don't include the ? and let it materialise.

The queries do not return any results, they are not functions. Like patterns the resuls are returned from out variable bindings in the parameters. The work in the same way that prolog predicates work, and you can find tuns of literatore on that.

see  2.2.2.8 has a fair overview of this:
http://docs.jboss.org/drools/release/5.3.0.Final/droolsjbpm-introduction-docs/html/releaseNotes.html#d0e50

see 5.9 here:
http://docs.jboss.org/drools/release/5.3.0.Final/drools-expert-docs/html/ch05.html#d0e6233

This should work for your example:
query query1(List $facts)
   $facts := List() from collect( Fact( name == "name1" ) )
end

query query2
   query1($l;)
end

The above $l should join with the results of query1, as it's unbound and thus an output variable.

Mark

On Mon, Nov 28, 2011 at 12:41 PM, Syargey <Syargey@tut.by> wrote:
I read in Drools guide, that queries can now call other queries.

But the guide doesn't give much details, mostly paying attention to a rather
specific case.

I have two queries having common parts and try to figure out how to  get rid
of duplicate code.

Here is the simplified form of queries I'd like to have:
---------

query query1
   $facts: List()
       from collect( Fact( name == "name1" ) )
end

query query2
   $l: List()
       from collect( Fact( value == "1" ) from ?query1() )
end

---------

query2 syntax is invalid and and it is not clear for me how $facts from
query1 can be accessed in query2.


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