diff --git a/PhysicsAnalysis/ElectronPhotonID/EgammaAnalysisHelpers/EgammaAnalysisHelpers/AsgEGammaConfigHelper.h b/PhysicsAnalysis/ElectronPhotonID/EgammaAnalysisHelpers/EgammaAnalysisHelpers/AsgEGammaConfigHelper.h
index c99faa4d49ac8669d3c1231de0f7914d6829bcb5..741b1ddd8be717468f7a7866aaf8c60f5871d390 100644
--- a/PhysicsAnalysis/ElectronPhotonID/EgammaAnalysisHelpers/EgammaAnalysisHelpers/AsgEGammaConfigHelper.h
+++ b/PhysicsAnalysis/ElectronPhotonID/EgammaAnalysisHelpers/EgammaAnalysisHelpers/AsgEGammaConfigHelper.h
@@ -1,30 +1,38 @@
 /*
-    Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
+    Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
 */
 
-
 // Dear emacs, this is -*-c++-*-
 #ifndef ASGELEGAMMACONFIGHELPER_H
 #define ASGELEGAMMACONFIGHELPER_H
 
 /**
-   @brief Tool to simplify the configuration of some egamma tools based on TEnv input
-   @author Christos Anastopoulos (2017) Nils Gillwald (DESY, 2020) nils.gillwald@desy.de
+   @brief Tool to simplify the configuration of some egamma tools based on TEnv
+   input
+   @author Christos Anastopoulos (2017) Nils Gillwald (DESY, 2020)
+   nils.gillwald@desy.de
    @date February 2020
 */
+#include <map>
 #include <string>
 #include <vector>
-#include <map>
 class TEnv;
 
-namespace AsgConfigHelper{
-  std::string  findConfigFile (const std::string& input, const std::map<std::string,std::string>& configmap);
-  unsigned int  findMask (const std::string& input, const std::map<std::string,unsigned int>& maskmap);
-  std::vector<double> HelperDouble(const std::string& input,  TEnv& env);  
-  std::vector<float> HelperFloat(const std::string& input,  TEnv& env);  
-  std::vector<int> HelperInt(const std::string& input, TEnv& env);
-  std::vector<std::string> HelperString(const std::string& input, TEnv& env);  
+namespace AsgConfigHelper {
+std::string
+findConfigFile(const std::string& input,
+               const std::map<std::string, std::string>& configmap);
+unsigned int
+findMask(const std::string& input,
+         const std::map<std::string, unsigned int>& maskmap);
+std::vector<double>
+HelperDouble(const std::string& input, TEnv& env);
+std::vector<float>
+HelperFloat(const std::string& input, TEnv& env);
+std::vector<int>
+HelperInt(const std::string& input, TEnv& env);
+std::vector<std::string>
+HelperString(const std::string& input, TEnv& env);
 }
 
-
-#endif //ASGEGAMMACONFIGHELPER_H
+#endif // ASGEGAMMACONFIGHELPER_H
diff --git a/PhysicsAnalysis/ElectronPhotonID/EgammaAnalysisHelpers/Root/AsgEGammaConfigHelper.cxx b/PhysicsAnalysis/ElectronPhotonID/EgammaAnalysisHelpers/Root/AsgEGammaConfigHelper.cxx
index 545b8e4b20bcc9d35e9c470dd700313e6db1220d..896fc07757ac47add829f25acc7da095bfae226d 100644
--- a/PhysicsAnalysis/ElectronPhotonID/EgammaAnalysisHelpers/Root/AsgEGammaConfigHelper.cxx
+++ b/PhysicsAnalysis/ElectronPhotonID/EgammaAnalysisHelpers/Root/AsgEGammaConfigHelper.cxx
@@ -1,117 +1,126 @@
 /*
-    Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
+    Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
 */
 
 #include "EgammaAnalysisHelpers/AsgEGammaConfigHelper.h"
 #include "AsgMessaging/AsgMessaging.h"
 #include "TEnv.h"
 #include <iostream>
-#include <sstream>   
+#include <sstream>
 
-namespace AsgConfigHelper{
+namespace AsgConfigHelper {
 
-  std::string findConfigFile (const std::string& input, const std::map<std::string,std::string>& configmap){
-    auto confFile_itr=configmap.find(input);
-    if(confFile_itr == configmap.end()){
-      static const asg::AsgMessaging msg("Egamma::AsgConfigHelper");
-      msg.msg(MSG::WARNING)<<"Key "<<input<<" not found in map, no config file returned"<<endmsg;
-      return "";
-    }
-    return confFile_itr->second;
-  }
-  
-  unsigned int findMask (const std::string& input, const std::map<std::string,unsigned int>& maskmap){
-    auto mask_itr=maskmap.find(input);
-    if(mask_itr==maskmap.end()){
-      static const asg::AsgMessaging msg("Egamma::AsgConfigHelper");
-      msg.msg(MSG::WARNING)<<"Key "<<input<<" not found in map,  egammaPID::EgPidUndefined mask returned"<<endmsg;
-      // mask has the choice to default to all 1 or all 0 bits, choose the former
-      return std::numeric_limits<unsigned int>::max();
-    }
-    return static_cast < unsigned int> (mask_itr->second);  
+std::string
+findConfigFile(const std::string& input,
+               const std::map<std::string, std::string>& configmap)
+{
+  auto confFile_itr = configmap.find(input);
+  if (confFile_itr == configmap.end()) {
+    static const asg::AsgMessaging msg("Egamma::AsgConfigHelper");
+    msg.msg(MSG::WARNING) << "Key " << input
+                          << " not found in map, no config file returned"
+                          << endmsg;
+    return "";
   }
+  return confFile_itr->second;
+}
 
-  template <typename T>
-  bool strtof(const std::string& input, T& f){  
-    int diff = 0 ;
-    std::string tmp = input;
-    std::string::size_type first(0);
-    std::string::size_type last(0);
-    first = ( input.find('#') ) ;
- 
-    //if we do not find a comment character "#" we are fine
-    if (first == std::string::npos) {
-      std::istringstream buffer (tmp);
-      buffer>>f;
-      return true;
-    } 
-    else {
-      //if we have found comment character check if it is inlined between two "#"
-      last = (input.find('#',first+1) );
-      //if nor error
-      if (last == std::string::npos) {
-        static const asg::AsgMessaging msg("Egamma::AsgConfigHelper");
-	      msg.msg(MSG::WARNING)<<" Improper comment format , inline comment should be enclosed between two #  "<<endmsg;
-	      return false;
-      }
-      //else if between two "#" remove this part 
-      diff = last - first ;
-      tmp= tmp.erase(first,diff+1);
-      std::istringstream buffer (tmp);
-      buffer>>f;
-      return true;
-    }
+unsigned int
+findMask(const std::string& input,
+         const std::map<std::string, unsigned int>& maskmap)
+{
+  auto mask_itr = maskmap.find(input);
+  if (mask_itr == maskmap.end()) {
+    static const asg::AsgMessaging msg("Egamma::AsgConfigHelper");
+    msg.msg(MSG::WARNING)
+      << "Key " << input
+      << " not found in map,  egammaPID::EgPidUndefined mask returned"
+      << endmsg;
+    // mask has the choice to default to all 1 or all 0 bits, choose the former
+    return std::numeric_limits<unsigned int>::max();
   }
+  return static_cast<unsigned int>(mask_itr->second);
+}
 
-  template <typename T>  
-  std::vector<T> Helper (const std::string& input,  TEnv& env){ 
-    std::vector<T> CutVector;    
-    std::string env_input(env.GetValue(input.c_str(), ""));
-    if (!env_input.empty()) {
-      std::string::size_type end;
-      do {
-	      end = env_input.find(';');
-	      T  myValue(0);
-	      if(AsgConfigHelper::strtof(env_input.substr(0,end),myValue)){
-	        CutVector.push_back(myValue);
-	      }
-	      if (end != std::string::npos) {
-	        env_input= env_input.substr(end+1);
-	      }
-      } while (end != std::string::npos);     
+template<typename T>
+bool
+strtof(const std::string& input, T& f)
+{
+  int diff = 0;
+  std::string tmp = input;
+  std::string::size_type first(0);
+  std::string::size_type last(0);
+  first = (input.find('#'));
+
+  // if we do not find a comment character "#" we are fine
+  if (first == std::string::npos) {
+    std::istringstream buffer(tmp);
+    buffer >> f;
+    return true;
+  } else {
+    // if we have found comment character check if it is inlined between two "#"
+    last = (input.find('#', first + 1));
+    // if nor error
+    if (last == std::string::npos) {
+      static const asg::AsgMessaging msg("Egamma::AsgConfigHelper");
+      msg.msg(MSG::WARNING) << " Improper comment format , inline comment "
+                               "should be enclosed between two #  "
+                            << endmsg;
+      return false;
     }
-    return CutVector;
+    // else if between two "#" remove this part
+    diff = last - first;
+    tmp = tmp.erase(first, diff + 1);
+    std::istringstream buffer(tmp);
+    buffer >> f;
+    return true;
   }
 }
 
-//use the specializations 
-std::vector<double> AsgConfigHelper::HelperDouble(const std::string& input,  TEnv& env){
-  return AsgConfigHelper::Helper<double> ( input,env);
-}
-std::vector<float> AsgConfigHelper::HelperFloat(const std::string& input,  TEnv& env){
-  return AsgConfigHelper::Helper<float> (input, env);  
-}
-std::vector<int> AsgConfigHelper::HelperInt(const std::string& input, TEnv& env){
-  return AsgConfigHelper::Helper<int> (input, env);  
-}
-// template does not work for std::string because of the T myValue(0); declaration, so implement it again for std::string
-std::vector<std::string> AsgConfigHelper::HelperString(const std::string& input, TEnv& env){
-  std::vector<std::string> CutVector;
+template<typename T>
+std::vector<T>
+Helper(const std::string& input, TEnv& env)
+{
+  std::vector<T> CutVector;
   std::string env_input(env.GetValue(input.c_str(), ""));
   if (!env_input.empty()) {
     std::string::size_type end;
     do {
-	    end = env_input.find(';');
-	    std::string myValue("");
-	    if(AsgConfigHelper::strtof(env_input.substr(0,end),myValue)){
-	      CutVector.push_back(myValue);
-	    }
-	    if (end != std::string::npos) {
-	      env_input= env_input.substr(end+1);
-	    }
+      end = env_input.find(';');
+      T myValue{}; //default init
+      if (AsgConfigHelper::strtof(env_input.substr(0, end), myValue)) {
+        CutVector.push_back(myValue);
+      }
+      if (end != std::string::npos) {
+        env_input = env_input.substr(end + 1);
+      }
     } while (end != std::string::npos);
   }
   return CutVector;
 }
+}
 
+// use the specializations
+std::vector<double>
+AsgConfigHelper::HelperDouble(const std::string& input, TEnv& env)
+{
+  return AsgConfigHelper::Helper<double>(input, env);
+}
+std::vector<float>
+AsgConfigHelper::HelperFloat(const std::string& input, TEnv& env)
+{
+  return AsgConfigHelper::Helper<float>(input, env);
+}
+std::vector<int>
+AsgConfigHelper::HelperInt(const std::string& input, TEnv& env)
+{
+  return AsgConfigHelper::Helper<int>(input, env);
+}
+// template does not work for std::string because of the T myValue(0);
+// declaration, so implement it again for std::string
+std::vector<std::string>
+AsgConfigHelper::HelperString(const std::string& input, TEnv& env)
+{
+  return AsgConfigHelper::Helper<std::string>(input, env);
+}
 
diff --git a/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/ElectronPhotonSelectorTools/AsgElectronSelectorTool.h b/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/ElectronPhotonSelectorTools/AsgElectronSelectorTool.h
index 099dc03f13cc73590c2243d96e1db1cb1a67ce48..ad9c9c2c10e306062e8fa8f82e1e631ca8c47f15 100644
--- a/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/ElectronPhotonSelectorTools/AsgElectronSelectorTool.h
+++ b/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/ElectronPhotonSelectorTools/AsgElectronSelectorTool.h
@@ -24,7 +24,7 @@ class AsgElectronSelectorTool final : public asg::AsgTool,
 
 public:
   /** Standard constructor */
-  AsgElectronSelectorTool( const std::string myname );
+  AsgElectronSelectorTool( const std::string& myname );
 
 
   /** Standard destructor */
diff --git a/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/Root/AsgElectronSelectorTool.cxx b/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/Root/AsgElectronSelectorTool.cxx
index 78af09403266eb927ec3f6c8d126a4a62207ffc0..f7c313efb57e44be9d318e248a8b625c5b22ec04 100644
--- a/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/Root/AsgElectronSelectorTool.cxx
+++ b/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/Root/AsgElectronSelectorTool.cxx
@@ -35,7 +35,7 @@
 //=============================================================================
 // Standard constructor
 //=============================================================================
-AsgElectronSelectorTool::AsgElectronSelectorTool( std::string myname ) :
+AsgElectronSelectorTool::AsgElectronSelectorTool( const std::string& myname ) :
   AsgTool(myname),
   m_configFile{""},
   m_mvaTool(nullptr)
@@ -86,7 +86,7 @@ StatusCode AsgElectronSelectorTool::initialize()
 
   if (!m_configFile.empty()){
     std::string configFile = PathResolverFindCalibFile(m_configFile);
-    if (configFile==""){
+    if (configFile.empty()){
       ATH_MSG_ERROR("Could not locate " << m_configFile);
       return StatusCode::FAILURE;
     }
@@ -170,7 +170,7 @@ StatusCode AsgElectronSelectorTool::initialize()
       return StatusCode::FAILURE;
     }
 
-    if (m_cutSCT.size()){
+    if (!m_cutSCT.empty()){
       if (m_cutSCT.size() != numberOfExpectedEtaBins){
         ATH_MSG_ERROR("Configuration issue :  cutSCT expected size " << numberOfExpectedEtaBins <<
                       " input size " << m_cutSCT.size());
@@ -178,7 +178,7 @@ StatusCode AsgElectronSelectorTool::initialize()
       }
     }
 
-    if (m_cutPi.size()){
+    if (!m_cutPi.empty()){
       if (m_cutPi.size() != numberOfExpectedEtaBins){
         ATH_MSG_ERROR("Configuration issue :  cutPi expected size " << numberOfExpectedEtaBins <<
                       " input size " << m_cutPi.size());
@@ -186,7 +186,7 @@ StatusCode AsgElectronSelectorTool::initialize()
       }
     }
 
-    if (m_cutBL.size()){
+    if (!m_cutBL.empty()){
       if (m_cutBL.size() != numberOfExpectedEtaBins){
         ATH_MSG_ERROR("Configuration issue :  cutBL expected size " << numberOfExpectedEtaBins <<
                       " input size " << m_cutBL.size());
@@ -194,7 +194,7 @@ StatusCode AsgElectronSelectorTool::initialize()
       }
     }
 
-    if (m_cutAmbiguity.size()){
+    if (!m_cutAmbiguity.empty()){
       if (m_cutAmbiguity.size() != numberOfExpectedEtaBins){
         ATH_MSG_ERROR("Configuration issue :  cutAmbiguity expected size " << numberOfExpectedEtaBins <<
                       " input size " << m_cutAmbiguity.size());
@@ -364,7 +364,7 @@ asg::AcceptData AsgElectronSelectorTool::accept( const EventContext& ctx, const
   if (!passKine){return acceptData;}
 
   // ambiguity bit
-  if (m_cutAmbiguity.size()){
+  if (!m_cutAmbiguity.empty()){
     if (!ElectronSelectorHelpers::passAmbiguity((xAOD::AmbiguityTool::AmbiguityType)ambiguityBit, m_cutAmbiguity[etaBin])){
       ATH_MSG_DEBUG("MVA macro: ambiguity Bit Failed.");
       passAmbiguity = false;
@@ -372,21 +372,21 @@ asg::AcceptData AsgElectronSelectorTool::accept( const EventContext& ctx, const
   }
 
   // blayer cut
-  if (m_cutBL.size()) {
+  if (!m_cutBL.empty()) {
     if(m_cutBL[etaBin] == 1 && !passBLayerRequirement){
       ATH_MSG_DEBUG("MVA macro: Blayer cut failed.");
       passNBlayer = false;
     }
   }
   // pixel cut
-  if (m_cutPi.size()){
+  if (!m_cutPi.empty()){
     if (nPixHitsPlusDeadSensors < m_cutPi[etaBin]){
       ATH_MSG_DEBUG("MVA macro: Pixels Failed.");
       passNPixel = false;
     }
   }
   // SCT cut
-  if (m_cutSCT.size()){
+  if (!m_cutSCT.empty()){
     if (nSiHitsPlusDeadSensors < m_cutSCT[etaBin]){
       ATH_MSG_DEBUG( "MVA macro: Silicon Failed.");
       passNSilicon = false;
@@ -396,7 +396,7 @@ asg::AcceptData AsgElectronSelectorTool::accept( const EventContext& ctx, const
   double cutDiscriminant;
   unsigned int ibin_combinedMVA = etBin*s_fnDiscEtaBins+etaBin; // Must change if number of eta bins changes!.
 
-  if (m_cutSelector.size()){
+  if (!m_cutSelector.empty()){
     // To protect against a binning mismatch, which should never happen
     if (ibin_combinedMVA >= m_cutSelector.size()){
       throw std::runtime_error("AsgElectronSelectorTool: The desired eta/pt bin is outside of the range specified by the input. This should never happen! This indicates a mismatch between the binning in the configuration file and the tool implementation." );
diff --git a/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/Root/ElectronDNNCalculator.cxx b/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/Root/ElectronDNNCalculator.cxx
index 82ff89af492f6ff9cb06b92677c3aacc25e28ec0..4397863948ed5e4fa49d5f2e11e894c2e5bb6706 100644
--- a/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/Root/ElectronDNNCalculator.cxx
+++ b/PhysicsAnalysis/ElectronPhotonID/ElectronPhotonSelectorTools/Root/ElectronDNNCalculator.cxx
@@ -31,7 +31,7 @@ ElectronDNNCalculator::ElectronDNNCalculator(AsgElectronSelectorTool* owner,
 {
   ATH_MSG_INFO("Initializing ElectronDNNCalculator...");
 
-  if (modelFileName.size() == 0){
+  if (modelFileName.empty()){
     throw std::runtime_error("No file found at '" + modelFileName + "'");
   }
 
@@ -56,7 +56,7 @@ ElectronDNNCalculator::ElectronDNNCalculator(AsgElectronSelectorTool* owner,
   m_graph = std::make_unique<lwt::generic::FastGraph<float>>(parsedGraph, order);
 
 
-  if (quantileFileName.size() == 0){
+  if (quantileFileName.empty()){
     throw std::runtime_error("No file found at '" + quantileFileName + "'");
   }
 
@@ -150,7 +150,7 @@ int ElectronDNNCalculator::readQuantileTransformer( TTree* tree, const std::vect
   sc = tree->SetBranchAddress("references", &references) == -5 ? 0 : 1;
 
   std::map<std::string, double> readVars;
-  for ( auto var : variables ){
+  for ( const auto& var : variables ){
       sc = tree->SetBranchAddress(TString(var), &readVars[var]) == -5 ? 0 : 1;
   }
   for (int i = 0; i < tree->GetEntries(); i++){