From 5856cd842f6ba229f758cc13c56b6db4841a6fe5 Mon Sep 17 00:00:00 2001
From: Oliver Lantwin <oliver.lantwin@cern.ch>
Date: Tue, 3 Dec 2024 16:18:23 +0100
Subject: [PATCH] Fix #569: Use std::swap instead of TVectorD::Use()

---
 CHANGELOG.md                               |  2 +-
 muonShieldOptimization/makeMuonDIS.py      | 10 +++++++---
 muonShieldOptimization/muDIS_mergeFiles.py |  8 ++++++--
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9ef8f7be8..d4988c14e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,7 +16,7 @@ it in future.
 
 ### Fixed
 
-* Use ConstructedAt instead of remove pythonization for TClonesArray
+* Use ConstructedAt + std::swap to replace removed pythonization for TCA
 * Octant symmetry was incorrect for B_z when using field maps (reported and fixed by M. Ferro-Luzzi)
 * Tof calculation corrected in GenieGenerator.cxx, wrong units previously used.
 
diff --git a/muonShieldOptimization/makeMuonDIS.py b/muonShieldOptimization/makeMuonDIS.py
index 7ecde9c63..7337abfee 100644
--- a/muonShieldOptimization/makeMuonDIS.py
+++ b/muonShieldOptimization/makeMuonDIS.py
@@ -80,12 +80,14 @@ def rotate(ctheta,stheta,cphi,sphi,px,py,pz):
   ctheta,stheta = ROOT.TMath.Cos(theta),ROOT.TMath.Sin(theta)
   cphi,sphi     = ROOT.TMath.Cos(phi),ROOT.TMath.Sin(phi)
   mu = array('d',[pid,px,py,pz,E,x,y,z,w])
-  muPart = ROOT.TVectorD(9,mu)
   myPythia.Initialize('FIXT',mutype[pid],'p+',p)
   for n in range(nMult):
      dPart.Clear()
      iMuon.Clear()
-     iMuon.ConstructedAt(0).Use(muPart)
+     tca_vec = iMuon.ConstructedAt(0)
+     muPart = ROOT.TVectorD(9, mu)
+     tca_vec.ResizeTo(muPart)
+     ROOT.std.swap(tca_vec, muPart)
      myPythia.GenerateEvent()
 # remove all unnecessary stuff
      myPythia.Pyedit(2)
@@ -99,7 +101,9 @@ def rotate(ctheta,stheta,cphi,sphi,px,py,pz):
 # copy to branch
       nPart = dPart.GetEntries()
       if dPart.GetSize() == nPart: dPart.Expand(nPart+10)
-      dPart.ConstructedAt(nPart).Use(part)
+      tca_vec = dPart.ConstructedAt(nPart)
+      tca_vec.ResizeTo(part)
+      ROOT.std.swap(tca_vec, part)
      nMade+=1
      if nMade%10000==0: print('made so far ',nMade)
      dTree.Fill()
diff --git a/muonShieldOptimization/muDIS_mergeFiles.py b/muonShieldOptimization/muDIS_mergeFiles.py
index abedbb4c9..c44372d0d 100644
--- a/muonShieldOptimization/muDIS_mergeFiles.py
+++ b/muonShieldOptimization/muDIS_mergeFiles.py
@@ -16,11 +16,15 @@ def merge():
    sTree.GetEvent(n)
    dPart.Clear()
    iMuon.Clear()
-   iMuon.ConstructedAt(0).Use(sTree.InMuon[0])
+   tca_vec = iMuon.ConstructedAt(0)
+   tca_vec.ResizeTo(sTree.InMuon[0])
+   ROOT.std.swap(tca_vec, sTree.InMuon[0])
    for part in sTree.Particles:
       nPart = dPart.GetEntries()
       if dPart.GetSize() == nPart: dPart.Expand(nPart+10)
-      dPart.ConstructedAt(nPart).Use(part)
+      tca_vec = dPart.ConstructedAt(nPart)
+      tca_vec.ResizeTo(part)
+      ROOT.std.swap(tca_vec, part)
    dPartBranch.Fill()
    iMuonBranch.Fill()
    nTree.Fill()