On Wed, Mar 18, 2009 at 6:44 PM, Qian Xu <[email protected]> wrote: > Frank Benoit wrote: >> >> Qian Xu schrieb: >> ----------- code 2 (current solution) -------------- >>> >>> public test(MyObj obj) >>> { >>> if (obj !is null && >>> obj.getObj2 !is null && >>> obj.getObj2.getObj3 !is null) >>> { >>> obj.getObj2.getObj3.test(); >>> } >>> } >>> >>> ------------------------------------------------------ >> >> If you want to be able to return something like "nothing", you can use >> NullObject. That is, return an object that lets you navigate the >> references and lets you test for it being a "null" object. >> >> auto o = obj.getObj2.getObj3; >> if( !o.isNull() ){ >> o.test(); >> } > > Hi, I have tried your code > > But gdc said, "Error: no property 'isNull' for type > 'NullPointerExceptionTest.MyObj' > > Did I miss something?
He's talking about this, I think: http://en.wikipedia.org/wiki/Null_Object_pattern
