Containers in GaudiPython E. Rodrigues, NIKHEF

1. LHCb Core Software Meeting Containers in GaudiPython E. Rodrigues, NIKHEF LHCb Core Software Meeting, 18 Jan. 2006

2. Access to Gaudi containers not natural/simple in Python The Standard Way import gaudimodule gaudi = gaudimodule.AppMgr() EVT = gaudi.evtsvc() >>> hits = EVT[ ‘Event/MC/OT/Hits’ ] >>> type(hits) <class 'gaudimodule.KeyedContainer<MCHit,Containers::KeyedObjectManager<Containers::hashmap> >'> >>> for i in range( hits.size() ): ... print hits.containedObject(i) # simple conversion container  Python list def toList( container ) : if container == None : return [] return [ container.containedObject(i) for i in range( container.size() ) ] >>> lhits = toList( hits ) >>> type(lhits) <type ‘list’> >>> for hit in lhits: ... print hit This would be preferred … … and is widely used in practice … LHCb Core Software Meeting, 18 Jan. 2006

3. Some possibilities … • Let’s agree for a second that we want to deal with containers naturally in (Gaudi)Python, i.e. as with lists or tuples • 1st option: every user drags “toList” definitions everywhere – not great • 2nd option: define a “toList” function centrally, say in gaudimodule.py • – one still has to call “toList” everywhere • 3rd option: incorporate the conversion in GaudiPython itself – my preference import gaudimodule gaudi = gaudimodule.AppMgr() LEVT = gaudi.levtsvc() IMAGINE A NEW SERVICE >>> hits = LEVT[ ‘Event/MC/OT/Hits’ ] >>> type(hits) >>> <type ‘list’> This is possible … LHCb Core Software Meeting, 18 Jan. 2006

4. Simple extension to gaudimodule.py class iListDataSvc( iDataSvc ) : def __getitem__( self, path ) : container = iDataSvc.__getitem__( self, path ) if container == None : return [] return [ container.containedObjects(i) for i in range( container.size() ) ] # inside the AppMgr class! class AppMgr( iService ) : # … def levtsvc( self ) : svc = Helper.service( self._svcloc, 'EventDataSvc' ) return iListDataSvc(name, svc) # … levtSvc = levtsvc PROPOSAL BTW: also works for the detector data service with the replacement ‘EventDataSvc’ by ‘DetectorDataSvc’ LHCb Core Software Meeting, 18 Jan. 2006