Adds copyBoundaryConditionFromFunction() method to BlockFunction

The commit moves the copyBoundaryConditionFromFunction() method up from
the P1CahnHilliardFunction to its base class. Then other children can
also make use of it.

src/hyteg/functions/BlockFunction.hpp

@@ -280,6 +280,16 @@ class BlockFunction
       }
    }
 
+   template < typename OtherType >
+   void copyBoundaryConditionFromFunction( const BlockFunction< OtherType >& other )
+   {
+      WALBERLA_ASSERT_EQUAL( subFunc_.size(), other.getNumberOfBlocks() );
+      for ( uint_t k = 0; k < subFunc_.size(); k++ )
+      {
+         subFunc_[k]->setBoundaryCondition( other.getSubFunction( k ).getBoundaryCondition() );
+      }
+   }
+
  protected:
    const std::string                                            functionName_;
    std::vector< std::shared_ptr< GenericFunction< value_t > > > subFunc_;

tutorials/08_CahnHilliard/CahnHilliard.cpp

@@ -552,16 +552,6 @@ class P1CahnHilliardFunction : public BlockFunction< value_t >
    {
       return this->getSubFunction( 1 ).template unwrap< P1Function< value_t > >();
    }
-
-   // TODO: Move this into BlockFunction
-   template < typename OtherFunctionValueType >
-   void copyBoundaryConditionFromFunction( const P1CahnHilliardFunction< OtherFunctionValueType >& other )
-   {
-      for ( uint_t k = 0; k < BlockFunction< value_t >::getNumberOfBlocks(); ++k )
-      {
-         BlockFunction< value_t >::getSubFunction( k ).setBoundaryCondition( other.getSubFunction( k ).getBoundaryCondition() );
-      }
-   }
 };
 /// [CahnHilliardFunction definition]