[RF] Avoid implicit creation of normalization set in RooNumRunningInt

Fixes this error when using the RooNumRunningInt class:

```
what():  calling RooAbsReal::getVal() with r-value references to the
normalization set is not allowed, because it breaks RooFits caching
logic and potentially introduces significant overhead. Please
explicitly create the RooArgSet outside the call to getVal().
```

Author: guitargeek

roofit/roofitcore/inc/RooNumRunningInt.h

@@ -24,7 +24,6 @@ class RooNumRunningInt : public RooAbsCachedReal {
   RooNumRunningInt(const char *name, const char *title, RooAbsReal& _func, RooRealVar& _x, const char* binningName="cache");
   RooNumRunningInt(const RooNumRunningInt& other, const char* name=nullptr) ;
   TObject* clone(const char* newname=nullptr) const override { return new RooNumRunningInt(*this,newname); }
-  ~RooNumRunningInt() override ;
 
 protected:
 
@@ -39,7 +38,7 @@ class RooNumRunningInt : public RooAbsCachedReal {
     RooNumRunningInt* _self ;
     std::vector<double> _ax ;
     std::vector<double> _ay ;
-    RooRealVar* _xx ;
+    RooArgSet _xx ;
 
   } ;
 

roofit/roofitcore/src/RooNumRunningInt.cxx

@@ -35,10 +35,6 @@ when any of the parameters of the input p.d.f. has changed.
 #include "RooHistPdf.h"
 #include "RooRealVar.h"
 
-using std::string;
-
-
-
 
 ////////////////////////////////////////////////////////////////////////////////
 /// Construct running integral of function '_func' over x_print from
@@ -71,26 +67,17 @@ RooNumRunningInt::RooNumRunningInt(const RooNumRunningInt& other, const char* na
  }
 
 
-
-////////////////////////////////////////////////////////////////////////////////
-/// Destructor
-
-RooNumRunningInt::~RooNumRunningInt()
-{
-}
-
-
 ////////////////////////////////////////////////////////////////////////////////
 /// Return unique name for RooAbsCachedPdf cache components
 /// constructed from input function name
 
 const char* RooNumRunningInt::inputBaseName() const
 {
-  static string ret ;
+  static std::string ret ;
   ret = func.arg().GetName() ;
   ret += "_NUMRUNINT" ;
   return ret.c_str() ;
-} ;
+}
 
 
 
@@ -100,7 +87,7 @@ const char* RooNumRunningInt::inputBaseName() const
 RooNumRunningInt::RICacheElem::RICacheElem(const RooNumRunningInt &self, const RooArgSet *nset)
    : FuncCacheElem(self, nset),
      _self(&const_cast<RooNumRunningInt &>(self)),
-     _xx(static_cast<RooRealVar *>(hist()->get()->find(self.x.arg().GetName())))
+     _xx(*hist()->get()->find(self.x.arg().GetName()))
 {
   // Instantiate temp arrays
   _ax.resize(hist()->numEntries());
@@ -110,7 +97,7 @@ RooNumRunningInt::RICacheElem::RICacheElem(const RooNumRunningInt &self, const R
 
   for (int i=0 ; i<hist()->numEntries() ; i++) {
     hist()->get(i) ;
-    _ax[i] = _xx->getVal() ;
+    _ax[i] = static_cast<RooRealVar*>(_xx.first())->getVal() ;
     _ay[i] = -1 ;
   }
 
@@ -125,7 +112,7 @@ RooArgList RooNumRunningInt::RICacheElem::containedArgs(Action action)
   RooArgList ret ;
   ret.add(FuncCacheElem::containedArgs(action)) ;
   ret.add(*_self) ;
-  ret.add(*_xx) ;
+  ret.add(_xx) ;
   return ret ;
 }
 
@@ -234,8 +221,8 @@ void RooNumRunningInt::RICacheElem::addRange(Int_t ixlo, Int_t ixhi, Int_t nbins
 void RooNumRunningInt::RICacheElem::addPoint(Int_t ix)
 {
   hist()->get(ix) ;
-  _self->x = _xx->getVal() ;
-  _ay[ix] = _self->func.arg().getVal(*_xx) ;
+  _self->x = static_cast<RooRealVar*>(_xx.first())->getVal() ;
+  _ay[ix] = _self->func.arg().getVal(_xx) ;
 
 }
 
@@ -295,5 +282,3 @@ double RooNumRunningInt::evaluate() const
   std::cout << "RooNumRunningInt::evaluate(" << GetName() << ")" << std::endl ;
   return 0 ;
 }
-
-