Add support to DataWriteHandle for writing 'views' into the TES

Allow a second template argument on `DataObjectWriteHandle` eg.
DataObjectWriteHandle<GetType,PutType> (note: by default, in case
of a single template argument, PutType=GetType, and the original
behaviour is kept).  In this case, `DataObjectWriteHandle::put`
will accept an rvalue reference to `PutType`, which it will create
a dedicated 'wrapper', which contains both the moved instance of
`PutType` as well as a `GetType` constructed from the moved instance,
into the event store. This wrapper can be retrieved and unwrapped
by a `DataObjectReadHandle<GetType>`.

GaudiAlg/include/GaudiAlg/FunctionalDetails.h

@@ -144,13 +144,13 @@ namespace Gaudi::Functional::details {
 
   template <typename Out1, typename Out2,
             typename = std::enable_if_t<std::is_constructible_v<Out1, Out2> && std::is_base_of_v<DataObject, Out1>>>
-  Out1* put( const DataObjectHandle<Out1>& out_handle, Out2&& out ) {
+  auto put( const DataObjectHandle<Out1>& out_handle, Out2&& out ) {
     return out_handle.put( std::make_unique<Out1>( std::forward<Out2>( out ) ) );
   }
 
   template <typename Out1, typename Out2, typename = std::enable_if_t<std::is_constructible_v<Out1, Out2>>>
-  void put( const DataObjectHandle<AnyDataWrapper<Out1>>& out_handle, Out2&& out ) {
-    out_handle.put( std::forward<Out2>( out ) );
+  auto put( const DataObjectHandle<AnyDataWrapper<Out1>>& out_handle, Out2&& out ) {
+    return out_handle.put( std::forward<Out2>( out ) );
   }
 
   // optional put

GaudiAlg/include/GaudiAlg/FunctionalUtilities.h

@@ -85,6 +85,12 @@ namespace Gaudi::Functional {
       using OutputHandle = Handle<T>;
     };
 
+    template <typename Data, typename View>
+    struct writeViewFor {
+      template <typename T>
+      using OutputHandle = std::enable_if_t<std::is_same_v<T, Data>, DataObjectWriteHandle<View, Data>>;
+    };
+
     // this uses the defaults -- and it itself is the default ;-)
     using useDefaults = use_<>;
 

GaudiAlg/include/GaudiAlg/GetData.h

@@ -79,13 +79,9 @@ namespace Gaudi {
     typename _GetType<TYPE>::return_type getFromTS( IDataProviderSvc* service, std::string_view location ) {
       DataObject* obj = nullptr;
       // Return the casted pointer if the retrieve was successful or nullptr otherwise.
-      StatusCode sc = service->retrieveObject( location, obj );
-      if ( sc.isSuccess() ) {
-        typename _GetType<TYPE>::return_type tobj = dynamic_cast<typename _GetType<TYPE>::return_type>( obj );
-        return tobj;
-      } else {
-        return nullptr;
-      }
+      return service->retrieveObject( location, obj ).isSuccess()
+                 ? dynamic_cast<typename _GetType<TYPE>::return_type>( obj )
+                 : nullptr;
     }
     // ========================================================================
     /** Helper function to provide the minimal lookup and cast functionality
@@ -98,17 +94,13 @@ namespace Gaudi {
       DataObject* obj = nullptr;
       // Return the casted pointer if the retrieve was successful or nullptr otherwise.
       StatusCode sc = service->retrieveObject( location, obj );
-      if ( sc.isSuccess() ) {
-        typename _GetType<TYPE>::return_type tobj = dynamic_cast<typename _GetType<TYPE>::return_type>( obj );
-        if ( !tobj ) {
-          // try with AnyDataWrapper
-          AnyDataWrapper<TYPE>* tobj2 = dynamic_cast<AnyDataWrapper<TYPE>*>( obj );
-          if ( tobj2 ) { tobj = &( tobj2->getData() ); }
-        }
-        return tobj;
-      } else {
-        return nullptr;
+      if ( sc.isFailure() ) return nullptr;
+      auto tobj = dynamic_cast<typename _GetType<TYPE>::return_type>( obj );
+      if ( !tobj ) {
+        // try with AnyDataWrapper
+        if ( auto tobj2 = dynamic_cast<AnyDataWrapper<TYPE>*>( obj ); tobj2 ) { tobj = &( tobj2->getData() ); }
       }
+      return tobj;
     }
     // ========================================================================
     /** @struct GetData GaudiUtils/GetData.h

GaudiExamples/CMakeLists.txt

@@ -40,8 +40,8 @@ gaudi_add_module(GaudiExamples
                          src/AlgTools/TestToolAlg.cpp
                          src/AlgTools/TestToolAlgFailure.cpp
                          src/AlgTools/TestToolFailing.cpp
-                         src/AnyData/AnyDataGetAlgorithm.cpp
-                         src/AnyData/AnyDataPutAlgorithm.cpp
+                         src/AnyData/AnyDataAlgorithm.cpp
+                         src/AnyData/AnyViewAlgorithm.cpp
                          src/Auditors/AuditorTestAlg.cpp
                          src/Auditors/LoggingAuditor.cpp
                          src/bug_34121/bug34121_MyAlgorithm.cpp

GaudiExamples/src/AnyData/AnyDataGetAlgorithm.cpp → GaudiExamples/src/AnyData/AnyDataAlgorithm.cpp

@@ -8,48 +8,85 @@
 * granted to it by virtue of its status as an Intergovernmental Organization        *
 * or submit itself to any jurisdiction.                                             *
 \***********************************************************************************/
-// Include files
-#include <vector>
-
-// from Gaudi
+#include "GaudiAlg/GaudiAlgorithm.h"
 #include "GaudiKernel/AnyDataWrapper.h"
-
-// local
-#include "AnyDataGetAlgorithm.h"
-
+#include "GaudiKernel/DataObjectHandle.h"
+#include <string>
+#include <vector>
 //-----------------------------------------------------------------------------
-// Implementation file for class : AnyDataGetAlgorithm
+// Implementation file for class : AnyData{Get,Put}Algorithm
 //
 // 2016-05-26 : Roel Aaij
 //-----------------------------------------------------------------------------
+/** @class AnyDataPutAlgorithm AnyDataPutAlgorithm.h AnyData/AnyDataPutAlgorithm.h
+ *
+ *
+ *  @author Roel Aaij
+ *  @date   2016-05-26
+ */
+class AnyDataPutAlgorithm : public GaudiAlgorithm {
+  Gaudi::Property<std::string>            m_loc{this, "Location", "Test"};
+  DataObjectWriteHandle<std::vector<int>> m_ids{this, "Output", "/Event/Test/Ids"};
+  std::vector<DataObjectWriteHandle<int>> m_id_vec;
 
-// Declaration of the Algorithm Factory
-DECLARE_COMPONENT_WITH_ID( AnyDataGetAlgorithm<int>, "AnyDataGetAlgorithm_Int" )
-DECLARE_COMPONENT_WITH_ID( AnyDataGetAlgorithm<std::vector<int>>, "AnyDataGetAlgorithm_VectorInt" )
+public:
+  AnyDataPutAlgorithm( const std::string& name, ISvcLocator* pSvcLocator ) : GaudiAlgorithm( name, pSvcLocator ) {
+    for ( int i = 0; i < 100; i++ ) { m_id_vec.emplace_back( "/Event/Test/Ids" + std::to_string( i ), this ); }
+  }
+
+  StatusCode execute() override {
+    if ( msgLevel( MSG::DEBUG ) ) debug() << "==> Execute" << endmsg;
+
+    auto i = std::make_unique<AnyDataWrapper<int>>( 0 );
+    auto j = std::make_unique<AnyDataWrapper<std::vector<int>>>( std::vector<int>{0, 1, 2, 3} );
 
-namespace {
-  using std::vector;
-}
+    put( std::move( i ), m_loc + "/One" );
+    put( std::move( j ), m_loc + "/Two" );
 
-//=============================================================================
-// Main execution
-//=============================================================================
+    m_ids.put( std::vector<int>( {42, 84} ) );
+
+    for ( int i = 0; i < 100; ++i ) m_id_vec[i].put( std::move( i ) );
+
+    return StatusCode::SUCCESS;
+  }
+};
+
+// Declaration of the Algorithm Factory
+DECLARE_COMPONENT( AnyDataPutAlgorithm )
+/** @class AnyDataGetAlgorithm AnyDataGetAlgorithm.h AnyData/AnyDataGetAlgorithm.h
+ *
+ *
+ *  @author Roel Aaij
+ *  @date   2016-05-26
+ */
 template <class T>
-StatusCode AnyDataGetAlgorithm<T>::execute() {
+class AnyDataGetAlgorithm : public GaudiAlgorithm {
+  Gaudi::Property<std::string> m_location{this, "Location"};
+
+  DataObjectReadHandle<std::vector<int>> m_ids{this, "Input", "/Event/Test/Ids"};
 
-  if ( msgLevel( MSG::DEBUG ) ) debug() << "==> Execute" << endmsg;
+public:
+  using GaudiAlgorithm::GaudiAlgorithm;
 
-  auto base = getIfExists<AnyDataWrapperBase>( m_location );
-  if ( base ) { info() << "Got base from " << m_location.value() << endmsg; }
-  const auto i = dynamic_cast<const AnyDataWrapper<T>*>( base );
-  if ( i ) {
-    info() << "Got " << System::typeinfoName( typeid( T ) ) << " from " << m_location.value() << ": " << i->getData()
-           << endmsg;
+  StatusCode execute() override {
+    if ( msgLevel( MSG::DEBUG ) ) debug() << "==> Execute" << endmsg;
+
+    auto base = getIfExists<AnyDataWrapperBase>( m_location );
+    if ( base ) { info() << "Got base from " << m_location.value() << endmsg; }
+    const auto i = dynamic_cast<const AnyDataWrapper<T>*>( base );
+    if ( i ) {
+      info() << "Got " << System::typeinfoName( typeid( T ) ) << " from " << m_location.value() << ": " << i->getData()
+             << endmsg;
+    }
+
+    const auto& ids = m_ids.get();
+    info() << "AnyDataHandler holds:";
+    for ( const auto& i : *ids ) info() << i << " ";
+    info() << endmsg;
+    return StatusCode::SUCCESS;
   }
+};
 
-  const auto& ids = m_ids.get();
-  info() << "AnyDataHandler holds:";
-  for ( const auto& i : *ids ) info() << i << " ";
-  info() << endmsg;
-  return StatusCode::SUCCESS;
-}
+// Declaration of the Algorithm Factory
+DECLARE_COMPONENT_WITH_ID( AnyDataGetAlgorithm<int>, "AnyDataGetAlgorithm_Int" )
+DECLARE_COMPONENT_WITH_ID( AnyDataGetAlgorithm<std::vector<int>>, "AnyDataGetAlgorithm_VectorInt" )

GaudiExamples/src/AnyData/AnyDataPutAlgorithm.cpp

-/***********************************************************************************\
-* (c) Copyright 1998-2019 CERN for the benefit of the LHCb and ATLAS collaborations *
-*                                                                                   *
-* This software is distributed under the terms of the Apache version 2 licence,     *
-* copied verbatim in the file "LICENSE".                                            *
-*                                                                                   *
-* In applying this licence, CERN does not waive the privileges and immunities       *
-* granted to it by virtue of its status as an Intergovernmental Organization        *
-* or submit itself to any jurisdiction.                                             *
-\***********************************************************************************/
-// Include files
-#include <string>
-#include <vector>
-
-// from Gaudi
-#include "GaudiKernel/AnyDataWrapper.h"
-
-// local
-#include "AnyDataPutAlgorithm.h"
-
-//-----------------------------------------------------------------------------
-// Implementation file for class : AnyDataPutAlgorithm
-//
-// 2016-05-26 : Roel Aaij
-//-----------------------------------------------------------------------------
-
-// Declaration of the Algorithm Factory
-DECLARE_COMPONENT( AnyDataPutAlgorithm )
-
-//=============================================================================
-// Standard constructor, initializes variables
-//=============================================================================
-AnyDataPutAlgorithm::AnyDataPutAlgorithm( const std::string& name, ISvcLocator* pSvcLocator )
-    : GaudiAlgorithm( name, pSvcLocator ) {
-  for ( int i = 0; i < 100; i++ ) { m_id_vec.emplace_back( "/Event/Test/Ids" + std::to_string( i ), this ); }
-}
-
-//=============================================================================
-// Main execution
-//=============================================================================
-StatusCode AnyDataPutAlgorithm::execute() {
-
-  if ( msgLevel( MSG::DEBUG ) ) debug() << "==> Execute" << endmsg;
-
-  auto i = std::make_unique<AnyDataWrapper<int>>( 0 );
-  auto j = std::make_unique<AnyDataWrapper<std::vector<int>>>( std::vector<int>{0, 1, 2, 3} );
-
-  put( std::move( i ), m_loc + "/One" );
-  put( std::move( j ), m_loc + "/Two" );
-
-  m_ids.put( std::vector<int>( {42, 84} ) );
-
-  for ( int i = 0; i < 100; ++i ) m_id_vec[i].put( std::move( i ) );
-
-  return StatusCode::SUCCESS;
-}

GaudiExamples/src/AnyData/AnyDataPutAlgorithm.h

-/***********************************************************************************\
-* (c) Copyright 1998-2019 CERN for the benefit of the LHCb and ATLAS collaborations *
-*                                                                                   *
-* This software is distributed under the terms of the Apache version 2 licence,     *
-* copied verbatim in the file "LICENSE".                                            *
-*                                                                                   *
-* In applying this licence, CERN does not waive the privileges and immunities       *
-* granted to it by virtue of its status as an Intergovernmental Organization        *
-* or submit itself to any jurisdiction.                                             *
-\***********************************************************************************/
-#ifndef ANYDATA_ANADATAPUTALGORITHM_H
-#define ANYDATA_ANADATAPUTALGORITHM_H 1
-
-// Include files
-#include <string>
-#include <vector>
-
-// from Gaudi
-#include "GaudiAlg/GaudiAlgorithm.h"
-#include "GaudiKernel/AnyDataHandle.h"
-
-/** @class AnyDataPutAlgorithm AnyDataPutAlgorithm.h AnyData/AnyDataPutAlgorithm.h
- *
- *
- *  @author Roel Aaij
- *  @date   2016-05-26
- */
-class AnyDataPutAlgorithm : public GaudiAlgorithm {
-public:
-  /// Standard constructor
-  AnyDataPutAlgorithm( const std::string& name, ISvcLocator* pSvcLocator );
-
-  StatusCode execute() override; ///< Algorithm execution
-
-private:
-  Gaudi::Property<std::string> m_loc{this, "Location", "Test"};
-
-  DataObjectWriteHandle<std::vector<int>> m_ids{this, "Output", "/Event/Test/Ids"};
-
-  std::vector<DataObjectWriteHandle<int>> m_id_vec;
-};
-#endif // ANYDATA_ANADATAPUTALGORITHM_H

GaudiExamples/src/AnyData/AnyDataGetAlgorithm.h → GaudiExamples/src/AnyData/AnyViewAlgorithm.cpp

@@ -8,33 +8,58 @@
 * granted to it by virtue of its status as an Intergovernmental Organization        *
 * or submit itself to any jurisdiction.                                             *
 \***********************************************************************************/
-#ifndef ANYDATA_ANADATAGETALGORITHM_H
-#define ANYDATA_ANADATAGETALGORITHM_H 1
-
-// Include files
+#include "GaudiAlg/Consumer.h"
+#include "GaudiAlg/Producer.h"
+#include "GaudiKernel/Algorithm.h"
+#include "GaudiKernel/DataObjectHandle.h"
+#include <gsl/span>
 #include <string>
+#include <string_view>
 #include <vector>
 
-// from Gaudi
-#include "GaudiAlg/GaudiAlgorithm.h"
-#include "GaudiKernel/DataObjectHandle.h"
-/** @class AnyDataGetAlgorithm AnyDataGetAlgorithm.h AnyData/AnyDataGetAlgorithm.h
- *
- *
- *  @author Roel Aaij
- *  @date   2016-05-26
- */
-template <class T>
-class AnyDataGetAlgorithm : public GaudiAlgorithm {
-public:
-  /// Standard constructor
-  AnyDataGetAlgorithm( const std::string& name, ISvcLocator* svcLoc ) : GaudiAlgorithm( name, svcLoc ) {}
-
-  StatusCode execute() override; ///< Algorithm execution
-
-private:
-  Gaudi::Property<std::string> m_location{this, "Location"};
-
-  DataObjectReadHandle<std::vector<int>> m_ids{this, "Input", "/Event/Test/Ids"};
+using BaseClass_t = Gaudi::Functional::Traits::BaseClass_t<Gaudi::Algorithm>;
+
+template <typename Data, typename View>
+using writeViewFor = Gaudi::Functional::Traits::use_<Gaudi::Functional::Traits::writeViewFor<Data, View>, BaseClass_t>;
+
+struct ProduceStringView : Gaudi::Functional::Producer<std::string(), writeViewFor<std::string, std::string_view>> {
+  ProduceStringView( const std::string& name, ISvcLocator* svcLoc )
+      : Producer{name, svcLoc, {"Output", "/Event/Test/StringView"}} {}
+
+  std::string operator()() const override { return "Hello World"; }
+};
+DECLARE_COMPONENT( ProduceStringView )
+
+struct ProduceIntView
+    : Gaudi::Functional::Producer<std::vector<int>(), writeViewFor<std::vector<int>, gsl::span<const int>>> {
+  ProduceIntView( const std::string& name, ISvcLocator* svcLoc )
+      : Producer{name, svcLoc, {"Output", "/Event/Test/IntView"}} {}
+
+  std::vector<int> operator()() const override {
+    std::vector<int> vi{1, 2, 3, 5, 8, 13, 21, 34};
+    info() << "made vector with data at : " << vi.data() << endmsg;
+    return vi;
+  }
+};
+DECLARE_COMPONENT( ProduceIntView )
+
+struct GetStringView : Gaudi::Functional::Consumer<void( std::string_view const& ), BaseClass_t> {
+  GetStringView( const std::string& name, ISvcLocator* svcLoc )
+      : Consumer{name, svcLoc, {"Input", "/Event/Test/StringView"}} {}
+
+  void operator()( const std::string_view& sv ) const override { info() << sv << endmsg; }
+};
+DECLARE_COMPONENT( GetStringView )
+
+struct GetIntView : Gaudi::Functional::Consumer<void( gsl::span<const int> const& ), BaseClass_t> {
+  GetIntView( const std::string& name, ISvcLocator* svcLoc )
+      : Consumer{name, svcLoc, {"Input", "/Event/Test/IntView"}} {}
+
+  void operator()( const gsl::span<const int>& view ) const override {
+    info() << "got a span with data at : " << view.data() << endmsg;
+    auto& out = info();
+    for ( int i : view ) out << i << " ";
+    out << endmsg;
+  }
 };
-#endif // ANYDATA_ANADATAGETALGORITHM_H
+DECLARE_COMPONENT( GetIntView )

GaudiExamples/tests/qmtest/gaudiexamples.qms/anyview.qmt

+<?xml version="1.0" ?><!DOCTYPE extension  PUBLIC '-//QM/2.3/Extension//EN'  'http://www.codesourcery.com/qm/dtds/2.3/-//qm/2.3/extension//en.dtd'>
+<!--
+    (c) Copyright 1998-2019 CERN for the benefit of the LHCb and ATLAS collaborations
+
+    This software is distributed under the terms of the Apache version 2 licence,
+    copied verbatim in the file "LICENSE".
+
+    In applying this licence, CERN does not waive the privileges and immunities
+    granted to it by virtue of its status as an Intergovernmental Organization
+    or submit itself to any jurisdiction.
+-->
+<extension class="GaudiTest.GaudiExeTest" kind="test">
+<argument name="program"><text>gaudirun.py</text></argument>
+<argument name="options"><text>
+from Gaudi.Configuration import *
+
+from Configurables import  ProduceStringView, ProduceIntView, GetStringView, GetIntView
+
+from Configurables import EvtDataSvc
+EvtDataSvc("EventDataSvc").RootCLID = 1
+EvtDataSvc("EventDataSvc").RootName = "/Event"
+EvtDataSvc("EventDataSvc").ForceLeaves = True
+app = ApplicationMgr(TopAlg = [ ProduceStringView(), ProduceIntView(), GetStringView(), GetIntView() ],
+                     EvtSel = "NONE",
+                     EvtMax = 2)
+</text></argument>
+    <argument name="reference"><text>refs/anyview.ref</text></argument>
+    <argument name="exit_code"><integer>0</integer></argument>
+</extension>

GaudiExamples/tests/qmtest/refs/anyview.ref

+# setting LC_ALL to "C"
+# --> Including file '/tmp/tmpz_UACG.py'
+# <-- End of file '/tmp/tmpz_UACG.py'
+ApplicationMgr    SUCCESS
+====================================================================================================================================
+                                                   Welcome to ApplicationMgr (GaudiCoreSvc v34r1)
+                                          running on stbc-i1.nikhef.nl on Sat Nov  7 15:16:48 2020
+====================================================================================================================================
+ApplicationMgr       INFO Application Manager Configured successfully
+EventLoopMgr      WARNING Unable to locate service "EventSelector"
+EventLoopMgr      WARNING No events will be processed from external input.
+ApplicationMgr       INFO Application Manager Initialized successfully
+ApplicationMgr       INFO Application Manager Started successfully
+ProduceIntView       INFO made vector with data at : 0x1f6baf0
+GetStringView        INFO Hello World
+GetIntView           INFO got a span with data at : 0x1f6baf0
+GetIntView           INFO 1 2 3 5 8 13 21 34
+ProduceIntView       INFO made vector with data at : 0x1f6baf0
+GetStringView        INFO Hello World
+GetIntView           INFO got a span with data at : 0x1f6baf0
+GetIntView           INFO 1 2 3 5 8 13 21 34
+ApplicationMgr       INFO Application Manager Stopped successfully
+EventLoopMgr         INFO Histograms converted successfully according to request.
+ApplicationMgr       INFO Application Manager Finalized successfully
+ApplicationMgr       INFO Application Manager Terminated successfully

GaudiKernel/include/GaudiKernel/AnyDataWrapper.h

@@ -8,14 +8,12 @@
 * granted to it by virtue of its status as an Intergovernmental Organization        *
 * or submit itself to any jurisdiction.                                             *
 \***********************************************************************************/
-#ifndef GAUDIKERNEL_ANYDATAWRAPPER_H
-#define GAUDIKERNEL_ANYDATAWRAPPER_H
-
-// Include files
+#pragma once
 #include "GaudiKernel/DataObject.h"
 #include <cstddef>
 #include <iterator>
 #include <optional>
+#include <utility>
 
 namespace details {
   using std::size;
@@ -32,24 +30,37 @@ struct GAUDI_API AnyDataWrapperBase : DataObject {
   virtual std::optional<std::size_t> size() const = 0;
 };
 
-template <class T>
-class GAUDI_API AnyDataWrapper final : public AnyDataWrapperBase {
-public:
-  AnyDataWrapper( T&& data ) : m_data( std::move( data ) ){};
+template <typename T>
+class GAUDI_API AnyDataWrapper : public AnyDataWrapperBase {
+protected:
+  T m_data;
 
-  AnyDataWrapper( AnyDataWrapper&& other )
-      : AnyDataWrapperBase( std::move( other ) ), m_data( std::move( other.m_data ) ){};
+public:
+  AnyDataWrapper( T&& data ) : m_data{std::move( data )} {};
+  AnyDataWrapper( AnyDataWrapper&& )      = delete;
+  AnyDataWrapper( AnyDataWrapper const& ) = delete;
+  AnyDataWrapper& operator=( AnyDataWrapper&& ) = delete;
+  AnyDataWrapper& operator=( AnyDataWrapper const& ) = delete;
 
   const T& getData() const { return m_data; }
   T&       getData() { return m_data; }
 
   std::optional<std::size_t> size() const override {
     using details::size;
-    return size( m_data );
+    return size( getData() );
   }
-
-private:
-  T m_data;
 };
 
-#endif
+template <typename ViewType, typename OwnedType>
+class GAUDI_API AnyDataWithViewWrapper : public AnyDataWrapper<ViewType> {
+  OwnedType m_owned;
+
+public:
+  AnyDataWithViewWrapper( OwnedType&& data ) : AnyDataWrapper<ViewType>{{}}, m_owned{std::move( data )} {
+    AnyDataWrapper<ViewType>::m_data = ViewType{std::as_const( m_owned )};
+  }
+  AnyDataWithViewWrapper( AnyDataWithViewWrapper&& )      = delete;
+  AnyDataWithViewWrapper( AnyDataWithViewWrapper const& ) = delete;
+  AnyDataWithViewWrapper& operator=( AnyDataWithViewWrapper&& ) = delete;
+  AnyDataWithViewWrapper& operator=( AnyDataWithViewWrapper const& ) = delete;
+};

GaudiKernel/include/GaudiKernel/DataObjectHandle.h

@@ -69,21 +69,24 @@ namespace details {
     return ok;
   }
 
-  template <typename T>
+  template <typename T, typename U>
   struct Payload_helper {
-    using type = std::conditional_t<std::is_base_of_v<DataObject, T>, T, AnyDataWrapper<std::remove_const_t<T>>>;
+    using type =
+        std::conditional_t<std::is_base_of_v<DataObject, T> && std::is_same_v<T, U>, T,
+                           std::conditional_t<std::is_same_v<T, U>, AnyDataWrapper<std::remove_const_t<T>>,
+                                              AnyDataWithViewWrapper<std::remove_const_t<T>, std::remove_const_t<U>>>>;
   };
-  template <typename T>
-  struct Payload_helper<Gaudi::Range_<T>> {
+  template <typename T, typename U>
+  struct Payload_helper<Gaudi::Range_<T>, U> {
     using type = Gaudi::Range_<T>;
   };
-  template <typename T>
-  struct Payload_helper<Gaudi::NamedRange_<T>> {
+  template <typename T, typename U>
+  struct Payload_helper<Gaudi::NamedRange_<T>, U> {
     using type = Gaudi::NamedRange_<T>;
   };
 
-  template <typename T>
-  using Payload_t = typename Payload_helper<T>::type;
+  template <typename T, typename U = T>
+  using Payload_t = typename Payload_helper<T, U>::type;
 } // namespace details
 
 //---------------------------------------------------------------------------
@@ -173,10 +176,8 @@ T* DataObjectHandle<T>::get( bool mustExist ) const {
 template <typename T>
 T* DataObjectHandle<T>::put( std::unique_ptr<T> objectp ) const {
   assert( m_init );
-  StatusCode rc = m_EDS->registerObject( objKey(), objectp.get() );
-  if ( !rc.isSuccess() ) {
-    throw GaudiException( "Error in put of " + objKey(), "DataObjectHandle<T>::put", StatusCode::FAILURE );
-  }
+  StatusCode sc = m_EDS->registerObject( objKey(), objectp.get() );
+  if ( !sc.isSuccess() ) { throw GaudiException( "Error in put of " + objKey(), "DataObjectHandle<T>::put", sc ); }
   return objectp.release();
 }
 
@@ -296,7 +297,14 @@ public:
   /**
    * Register object in transient store
    */
-  const T* put( T&& object ) const;
+  const T* put( T&& obj ) const {
+    assert( m_init );
+    auto objectp = std::make_unique<AnyDataWrapper<T>>( std::move( obj ) );
+    if ( auto sc = m_EDS->registerObject( objKey(), objectp.get() ); sc.isFailure() ) {
+      throw GaudiException( "Error in put of " + objKey(), "DataObjectHandle<AnyDataWrapper<T>>::put", sc );
+    }
+    return &objectp.release()->getData();
+  }
 
   /**
    * Size of boxed item, if boxed item has a 'size' method
@@ -310,40 +318,81 @@ public:
   }
 
 private:
-  AnyDataWrapper<T>* _get( bool mustExist ) const;
-  mutable bool       m_goodType = false;
+  AnyDataWrapper<T>* _get( bool mustExist ) const {
+    auto obj = fetch();
+    if ( UNLIKELY( !obj ) ) {
+      if ( mustExist ) {
+        throw GaudiException( "Cannot retrieve " + objKey() + " from transient store.",
+                              m_owner ? owner()->name() : "no owner", StatusCode::FAILURE );
+
+      } else {
+        return nullptr;
+      }
+    }
+    if ( UNLIKELY( !m_goodType ) ) m_goodType = ::details::verifyType<AnyDataWrapper<T>>( obj );
+    return static_cast<AnyDataWrapper<T>*>( obj );
+  }
+  mutable bool m_goodType = false;
 };
 
 //---------------------------------------------------------------------------
+/// specialization for AnyDataWithViewWrapper
+template <typename View, typename Owned>
+class DataObjectHandle<AnyDataWithViewWrapper<View, Owned>> : public DataObjectHandleBase {
+public:
+  using DataObjectHandleBase::DataObjectHandleBase;
 
-template <typename T>
-AnyDataWrapper<T>* DataObjectHandle<AnyDataWrapper<T>>::_get( bool mustExist ) const {
-  auto obj = fetch();
-  if ( UNLIKELY( !obj ) ) {
-    if ( mustExist ) {
-      throw GaudiException( "Cannot retrieve " + objKey() + " from transient store.",
-                            m_owner ? owner()->name() : "no owner", StatusCode::FAILURE );
+  /**
+   * Retrieve object from transient data store
+   */
+  View* get() const { return &_get( true )->getData(); }
+  View* getIfExists() const {
+    auto data = _get( false );
+    return data ? &data->getData() : nullptr;
+  }
 
-    } else {
-      return nullptr;
+  /**
+   * Register object in transient store
+   */
+  const View* put( std::unique_ptr<AnyDataWithViewWrapper<View, Owned>> objectp ) const {
+    assert( m_init );
+    if ( auto sc = m_EDS->registerObject( objKey(), objectp.get() ); sc.isFailure() ) {
+      throw GaudiException( "Error in put of " + objKey(), "DataObjectHandle<AnyDataWithViewWrapper<T>::put", sc );
     }
+    return &objectp.release()->getData();
+  }
+  const View* put( Owned&& obj ) const {
+    return put( std::make_unique<AnyDataWithViewWrapper<View, Owned>>( std::move( obj ) ) );
   }
-  if ( UNLIKELY( !m_goodType ) ) m_goodType = ::details::verifyType<AnyDataWrapper<T>>( obj );
-  return static_cast<AnyDataWrapper<T>*>( obj );
-}
 
-//---------------------------------------------------------------------------
+  /**
+   * Size of boxed item, if boxed item has a 'size' method
+   */
+  std::optional<std::size_t> size() const { return _get()->size(); }
 
-template <typename T>
-const T* DataObjectHandle<AnyDataWrapper<T>>::put( T&& obj ) const {
-  assert( m_init );
-  auto       objectp = std::make_unique<AnyDataWrapper<T>>( std::move( obj ) );
-  StatusCode rc      = m_EDS->registerObject( objKey(), objectp.get() );
-  if ( rc.isFailure() ) {
-    throw GaudiException( "Error in put of " + objKey(), "DataObjectHandle<T>::put", StatusCode::FAILURE );
+  std::string pythonRepr() const override {
+    auto repr = DataObjectHandleBase::pythonRepr();
+    boost::replace_all( repr, default_type, System::typeinfoName( typeid( View ) ) );
+    return repr;
   }
-  return &objectp.release()->getData();
-}
+
+private:
+  AnyDataWithViewWrapper<View, Owned>* _get( bool mustExist ) const {
+    auto obj = fetch();
+    if ( UNLIKELY( !obj ) ) {
+      if ( mustExist ) {
+        throw GaudiException( "Cannot retrieve " + objKey() + " from transient store.",
+                              m_owner ? owner()->name() : "no owner", StatusCode::FAILURE );
+
+      } else {
+        return nullptr;
+      }
+    }
+    if ( UNLIKELY( !m_goodType ) ) m_goodType = ::details::verifyType<AnyDataWithViewWrapper<View, Owned>>( obj );
+    return static_cast<AnyDataWithViewWrapper<View, Owned>*>( obj );
+  }
+  mutable bool m_goodType = false;
+};
 
 //---------------------------- user-facing interface ----------
 
@@ -369,22 +418,22 @@ public:
       : DataObjectReadHandle( args, std::index_sequence_for<Args...>{} ) {}
 };
 
-template <typename T>
-class DataObjectWriteHandle : public DataObjectHandle<::details::Payload_t<T>> {
+template <typename T, typename U = T>
+class DataObjectWriteHandle : public DataObjectHandle<::details::Payload_t<T, U>> {
   template <typename... Args, std::size_t... Is>
   DataObjectWriteHandle( const std::tuple<Args...>& args, std::index_sequence<Is...> )
       : DataObjectWriteHandle( std::get<Is>( args )... ) {}
 
 public:
   DataObjectWriteHandle( const DataObjID& k, IDataHandleHolder* owner )
-      : DataObjectHandle<::details::Payload_t<T>>{k, Gaudi::DataHandle::Writer, owner} {}
+      : DataObjectHandle<::details::Payload_t<T, U>>{k, Gaudi::DataHandle::Writer, owner} {}
 
   /// Autodeclaring constructor with property name, mode, key and documentation.
   /// @note the use std::enable_if is required to avoid ambiguities
   template <typename OWNER, typename K, typename = std::enable_if_t<std::is_base_of_v<IProperty, OWNER>>>
   DataObjectWriteHandle( OWNER* owner, std::string propertyName, const K& key = {}, std::string doc = "" )
-      : DataObjectHandle<::details::Payload_t<T>>( owner, Gaudi::DataHandle::Writer, std::move( propertyName ), key,
-                                                   std::move( doc ) ) {}
+      : DataObjectHandle<::details::Payload_t<T, U>>( owner, Gaudi::DataHandle::Writer, std::move( propertyName ), key,
+                                                      std::move( doc ) ) {}
 
   template <typename... Args>
   DataObjectWriteHandle( const std::tuple<Args...>& args )