Re: [rules-users] Condition syntax to access Map

Whoa! See below... 2011/7/28 Edson Tirelli <ed.tirelli(a)gmail.com&gt; (Edson: Only if you define it so. The logical implication of c being null in an absent a.b (i.e., a.b==null) could very well be that "a.b.c does not exist", and you can't claim that a.b.c exists if a.b. doesn't! Is there no house at some address? (city.street[name].house[number] == null) # true => no such house This test data with false when null: Vienna/TirelliStrasse/42 returns "false", hence there *is* such a house. But we don't have a Tirelli Street in Vienna (yet)! Confer this to Perl's ! exists $city{-streets}{"Tirelli"}[42] ) Edson, Mark,... please do recall the times where you have had an NPE in the code in a boolean expression? How painful would it have been if Java would have returned "false", continuing to cover a coding error made elsewhere? Why don't other languages tolerate "null" silently? (Perl, the most pragmatic of all, doesn't - it has introduced an operator I can use or not.) I have no problem when folks want to take shortcuts and live la dolce vita, but <em>I don't want to be led into the bog without my consent.</em> So, a builder option to turn this on is allright with me. This is an entirely different matter than the previous one. I see no reason whatsoever, not to define this "from" as working with an implicit filter. -W