#include <CollHandle.h>

Public Member Functions
	CollHandle (const edm::InputTag &tag, bool failIfNotFound=true, bool notFoundWarn=true)
const T &	operator* () const
const T *	operator-> () const
void	read (const edm::Event &event)
edm::InputTag	tag () const
Private Attributes
const T *	currentColl_
const T	emptyColl_
bool	failIfNotFound_
bool	notFoundAlreadyWarned_
bool	notFoundWarn_
const edm::InputTag	tag_

Detailed Description

template<class T>
class CollHandle< T >

Utilitity class for handling an EDM data collection. This class acts as a wrapper of the EDM collection.

An InputTag indentifying the collection is passed to the constructor. The collection is retrieved from the event by a call to the read() method. The CollHandle class instance can then be used as a pointer to the retrieved collection.

Absence of the collection from the event can be optionnaly tolerated: see failIfNotFound parameter of the CollHandle() constructor.

In case the collection was not (yet) retrieved from the collection, it acts as a pointers to an empty collection.

The templace parameter T specifies the type of the data collection.

Definition at line 25 of file CollHandle.h.

Constructor & Destructor Documentation

template<class T>

CollHandle< T >::CollHandle	(	const edm::InputTag &	tag,
		bool	failIfNotFound = `true`,
		bool	notFoundWarn = `true`
	)		`[inline]`

Constructs a CollHandle.

Parameters:

tag	InputTag identifying the data collection
failIfNotFound	pass true if the absence of the collection in the event must be considered as an error. See read() method.

Definition at line 33 of file CollHandle.h.

                                      : tag_(tag),
                                        currentColl_(&emptyColl_),
                                        notFoundAlreadyWarned_(false),
                                        failIfNotFound_(failIfNotFound),
                                        notFoundWarn_(notFoundWarn){}

Member Function Documentation

template<class T>

const T& CollHandle< T >::operator* ( void ) const [inline]

Gets the collection retrieved by read() method. If the collection was absent from the event an empty collection is returned.

Definition at line 83 of file CollHandle.h.

{ return *currentColl_;}

template<class T>

const T* CollHandle< T >::operator-> ( ) const [inline]

Accessor to a member of the collection retrieved by read method(). Considering h a CollHandle instance, h->f() is equivalent to (*h).f().

Definition at line 78 of file CollHandle.h.

{ return currentColl_;}

template<class T>

void CollHandle< T >::read ( const edm::Event & event ) [inline]

Retrieves the collection from the event. If failIfNotFound is true and the collection is not found, then an edm::Exception is thrown. For other case of exception throw see edm::Event::getByLabel() method documentation. If failIfNotFound is false and the collection is not found, an empty collection is used; a warn message will be logged the first time the collection is not found.

Parameters:

event the EDM event the collection must be retrieved from.

Definition at line 51 of file CollHandle.h.

Referenced by EcalSelectiveReadoutValidation::readAllCollections().

                                  {
    //    try{
    edm::Handle<T> hColl;
    event.getByLabel(tag_, hColl);
  
    //If we must be tolerant to product absence, then
    //we must check validaty before calling Handle::operator*
    //to prevent exception throw:
    if(!failIfNotFound_     // product-not-found tolerant mode
       && !hColl.isValid()){// and the product was not found
      if(notFoundWarn_
         && !notFoundAlreadyWarned_){//warning logged only once
        edm::LogWarning("ProductNotFound") << tag_
                                           << " product "
          "of type '" << typeid(T).name() << "' was not found!";
        notFoundAlreadyWarned_ = true;
      }
      currentColl_ = &emptyColl_;
    } else {
      currentColl_ = &(*hColl);
    }
  }