Hi, I had some code which worked using CINT and when loading with gROOT->ProcessLine(“mycode.C+”). I am trying to compile it externally using clang++ (or g++), but I get errors about the ROOT::Math::Functor constructors.

Here is my error message:

```
clang++-mp-3.2 -std=c++11 -Wno-c++11-extensions -o ana do_ana.C -I`root-config --incdir` `root-config --glibs`
In file included from do_ana.C:12:
./JFTrackFit.C:294:23: error: no matching constructor for initialization of 'ROOT::Math::Functor'
ROOT::Math::Functor ftor(&jftf,2,"JFTrackFit");
^ ~~~~~~~~~~~~~~~~~~~~
/opt/local/include/root/Math/Functor.h:358:4: note: candidate constructor [with PtrObj = JFTrackFit *, MemFn = int] not viable: no
known conversion from 'const char [11]' to 'unsigned int' for 3rd argument
Functor(const PtrObj& p, MemFn memFn, unsigned int dim )
^
/opt/local/include/root/Math/Functor.h:369:4: note: candidate constructor template not viable: requires 2 arguments, but 3 were
provided
Functor( const Func & f, unsigned int dim ) :
^
/opt/local/include/root/Math/Functor.h:351:4: note: candidate constructor not viable: requires 0 arguments, but 3 were provided
Functor () : fImpl(0) {}
^
/opt/local/include/root/Math/Functor.h:389:4: note: candidate constructor not viable: requires single argument 'rhs', but 3
arguments were provided
Functor(const Functor & rhs) :
^
1 error generated.
```

Indeed it seems (when reading the .h file) that the constructor that I am using is protected by an #if defined(**CINT**) block. Online it is here: http://root.cern.ch/root/html/src/ROOT__Math__Functor.h.html#374

Unfortunately the other constructors at http://root.cern.ch/root/html/ROOT__Math__Functor.html are not clear. What is a MemFn object? In fact, the constructors in the summary list do not match those listed below, and there is no mention that one of the constructors only works in CINT.

What is the workaround? Thanks for any help.

Jean-François