No virtual methods in Container class

Either this way, or make all of them virtual

Author: franzpoeschel

include/openPMD/backend/BaseRecord.hpp

@@ -114,12 +114,12 @@ class BaseRecord
 
     virtual ~BaseRecord() = default;
 
-    mapped_type &operator[](key_type const &key) override;
-    mapped_type &operator[](key_type &&key) override;
+    mapped_type &operator[](key_type const &key);
+    mapped_type &operator[](key_type &&key);
     mapped_type &at(key_type const &key);
     mapped_type const &at(key_type const &key) const;
-    size_type erase(key_type const &key) override;
-    iterator erase(iterator res) override;
+    size_type erase(key_type const &key);
+    iterator erase(iterator res);
     //! @todo add also, as soon as added in Container:
     // iterator erase(const_iterator first, const_iterator last) override;
 

include/openPMD/backend/Container.hpp

@@ -283,7 +283,7 @@ class Container : virtual public Attributable
      * @throws  std::out_of_range error if in READ_ONLY mode and key does not
      * exist, otherwise key will be created
      */
-    virtual mapped_type &operator[](key_type const &key)
+    mapped_type &operator[](key_type const &key)
     {
         auto it = container().find(key);
         if (it != container().end())
@@ -318,7 +318,7 @@ class Container : virtual public Attributable
      * @throws  std::out_of_range error if in READ_ONLY mode and key does not
      * exist, otherwise key will be created
      */
-    virtual mapped_type &operator[](key_type &&key)
+    mapped_type &operator[](key_type &&key)
     {
         auto it = container().find(key);
         if (it != container().end())
@@ -382,7 +382,7 @@ class Container : virtual public Attributable
      * @param   key Key of the element to remove.
      * @return  Number of elements removed (either 0 or 1).
      */
-    virtual size_type erase(key_type const &key)
+    size_type erase(key_type const &key)
     {
         if (Access::READ_ONLY == IOHandler()->m_frontendAccess)
             throw std::runtime_error(
@@ -400,7 +400,7 @@ class Container : virtual public Attributable
     }
 
     //! @todo why does const_iterator not work compile with pybind11?
-    virtual iterator erase(iterator res)
+    iterator erase(iterator res)
     {
         if (Access::READ_ONLY == IOHandler()->m_frontendAccess)
             throw std::runtime_error(