Refactor to separate header

src/optimization/CasADiIterCallback.h

@@ -0,0 +1,31 @@
+#include "casadi/casadi.hpp"
+using namespace casadi;
+class CasADiIterCallback : public Callback {
+  // Data members
+  double d;
+public:
+  // Constructor
+  CasADiIterCallback(const std::string& name, double d,
+             const Dict& opts=Dict()) : d(d) {
+    construct(name, opts);
+  }
+
+  // Destructor
+  ~CasADiIterCallback() override {}
+
+  // Number of inputs and outputs
+  casadi_int get_n_in() override { return 1;}
+  casadi_int get_n_out() override { return 1;}
+
+  // Initialize the object
+  void init() override() {
+    std::cout << "initializing object" << std::endl;
+  }
+
+  // Evaluate numerically
+  std::vector<DM> eval(const std::vector<DM>& arg) const override {
+    DM x = arg.at(0);
+    DM f = sin(d*x);
+    return 1;
+  }
+};

src/optimization/CasADiOpti.cpp

@@ -2,6 +2,7 @@
 
 #ifdef OPTIMIZER_BACKEND_CASADI
 #include "optimization/CasADiOpti.h"
+#include "optimization/CasADiIterCallback.h"
 
 #include <casadi/casadi.hpp>
 #include <casadi/core/exception.hpp>

src/optimization/CasADiOpti.h

@@ -10,36 +10,6 @@
 
 namespace trajopt {
 
-class CasADiIterCallback : public Callback {
-  // Data members
-  double d;
-public:
-  // Constructor
-  CasADiIterCallback(const std::string& name, double d,
-             const Dict& opts=Dict()) : d(d) {
-    construct(name, opts);
-  }
-
-  // Destructor
-  ~CasADiIterCallback() override {}
-
-  // Number of inputs and outputs
-  casadi_int get_n_in() override { return 1;}
-  casadi_int get_n_out() override { return 1;}
-
-  // Initialize the object
-  void init() override() {
-    std::cout << "initializing object" << std::endl;
-  }
-
-  // Evaluate numerically
-  std::vector<DM> eval(const std::vector<DM>& arg) const override {
-    DM x = arg.at(0);
-    DM f = sin(d*x);
-    return {f};
-  }
-};
-
 class CasADiOpti {
  private:
   casadi::Opti opti;