22.7 Using your own Functors in OEChem

While many predefined functors exist it is not difficult to find a situation which calls for a new functor. Acquiring a complete understanding of functors can be daunting, but generating a functor to pass to OEChem functions is less difficult.

The following example shows a user defined functor which screens for atoms whose atomic mass is greater than 15.

#include "oechem.h"
#include "oesystem.h"

#include <iostream>

using namespace OESystem;
using namespace OEChem;
using namespace std;

class WeightGT15 : public OEUnaryPredicate<OEAtomBase>
{
public:
  bool operator()(const OEAtomBase &atom) const
  {
    return OEGetAverageWeight(atom.GetAtomicNum()) > 15;
  }
  OEUnaryFunction<OEAtomBase,bool> *CreateCopy() const
  {
    return new WeightGT15;
  }
protected:
  bool Eval(const OEAtomBase &atom) const { return operator()(atom); }
  bool Eval(const OEAtomBase &)           { return false; }
};

int main()
{
  OEGraphMol mol;
  OEParseSmiles(mol, "c1c(O)c(O)c(Cl)cc1CCCBr");

  OEIter<OEAtomBase> atom;
  for(atom = mol.GetAtoms(WeightGT15());atom;++atom)
    cout << atom->GetName() << " has weight > 15." << endl;

  return 0;
}

				OEChem - C++ Theory Manual Version 1.3.1

				OEChem - C++ Theory Manual Version 1.3.1