use RAII to set and reset temporary loop order for the tower

which is exception safe

templates/standard_model_matching.cpp.in

@@ -39,6 +39,54 @@ namespace flexiblesusy {
 #define SMPARAMETER(p) sm.get_##p()
 #define INPUTPARAMETER(p) model.get_input().p
 
+namespace {
+
+class Loop_order_setter {
+public:
+   Loop_order_setter(
+      Standard_model* sm_, @ModelName@_mass_eigenstates* model_, unsigned loop_order_)
+      : sm(sm_), model(model_), loop_order(loop_order_)
+   {
+      assert(sm);
+      assert(model);
+
+      // store old loop orders
+      model_pole_mass_order = model->get_pole_mass_loop_order();
+      model_ewsb_order      = model->get_ewsb_loop_order();
+      sm_pole_mass_order    = sm->get_pole_mass_loop_order();
+      sm_ewsb_order         = sm->get_ewsb_loop_order();
+
+      // temporarily set loop order to `loop_order'
+      model->set_pole_mass_loop_order(loop_order);
+      model->set_ewsb_loop_order(loop_order);
+      sm->set_pole_mass_loop_order(loop_order);
+      sm->set_ewsb_loop_order(loop_order);
+   }
+
+   ~Loop_order_setter() {
+      // reset loop order
+      model->set_pole_mass_loop_order(model_pole_mass_order);
+      model->set_ewsb_loop_order(model_ewsb_order);
+      sm->set_pole_mass_loop_order(sm_pole_mass_order);
+      sm->set_ewsb_loop_order(sm_ewsb_order);
+
+      model->calculate_DRbar_masses();
+      model->solve_ewsb();
+      sm->calculate_DRbar_masses();
+      sm->solve_ewsb();
+   }
+private:
+   Standard_model* sm;
+   @ModelName@_mass_eigenstates* model;
+   unsigned loop_order;            ///< temporary loop order
+   unsigned model_pole_mass_order; ///< old model pole mass loop order
+   unsigned model_ewsb_order;      ///< old model EWSB loop order
+   unsigned sm_pole_mass_order;    ///< old SM pole mass loop order
+   unsigned sm_ewsb_order;         ///< old SM EWSB loop order
+};
+
+} // anonymous namespace
+
 /**
  * Calculates \f$\lambda(Q)\f$ at the tree level from the lightest
  * CP-even Higgs boson mass of the @ModelName@.
@@ -66,31 +114,12 @@ void @ModelName@_standard_model_matching::match_high_to_low_scale_model(
    }
 
    // temporarily set loop order to `loop_order'
-   const unsigned model_pole_mass_order = model.get_pole_mass_loop_order();
-   const unsigned model_ewsb_order      = model.get_ewsb_loop_order();
-   const unsigned sm_pole_mass_order    = sm.get_pole_mass_loop_order();
-   const unsigned sm_ewsb_order         = sm.get_ewsb_loop_order();
-
-   model.set_pole_mass_loop_order(loop_order);
-   model.set_ewsb_loop_order(loop_order);
-   sm.set_pole_mass_loop_order(loop_order);
-   sm.set_ewsb_loop_order(loop_order);
+   Loop_order_setter los(&sm, &model, loop_order);
 
    match_high_to_low_scale_model(sm, model);
 
    model.get_physical().clear();
    sm.get_physical().clear();
-
-   // reset loop order
-   model.set_pole_mass_loop_order(model_pole_mass_order);
-   model.set_ewsb_loop_order(model_ewsb_order);
-   sm.set_pole_mass_loop_order(sm_pole_mass_order);
-   sm.set_ewsb_loop_order(sm_ewsb_order);
-
-   model.calculate_DRbar_masses();
-   model.solve_ewsb();
-   sm.calculate_DRbar_masses();
-   sm.solve_ewsb();
 }
 
 
@@ -198,31 +227,12 @@ void @ModelName@_standard_model_matching::match_low_to_high_scale_model(
    }
 
    // temporarily set loop order to `loop_order'
-   const unsigned model_pole_mass_order = model.get_pole_mass_loop_order();
-   const unsigned model_ewsb_order      = model.get_ewsb_loop_order();
-   const unsigned sm_pole_mass_order    = sm.get_pole_mass_loop_order();
-   const unsigned sm_ewsb_order         = sm.get_ewsb_loop_order();
-
-   model.set_pole_mass_loop_order(loop_order);
-   model.set_ewsb_loop_order(loop_order);
-   sm.set_pole_mass_loop_order(loop_order);
-   sm.set_ewsb_loop_order(loop_order);
+   Loop_order_setter los(&sm, &model, loop_order);
 
    match_low_to_high_scale_model(model, sm);
 
    model.get_physical().clear();
    sm.get_physical().clear();
-
-   // reset loop order
-   model.set_pole_mass_loop_order(model_pole_mass_order);
-   model.set_ewsb_loop_order(model_ewsb_order);
-   sm.set_pole_mass_loop_order(sm_pole_mass_order);
-   sm.set_ewsb_loop_order(sm_ewsb_order);
-
-   model.calculate_DRbar_masses();
-   model.solve_ewsb();
-   sm.calculate_DRbar_masses();
-   sm.solve_ewsb();
 }
 
 /**