feat: more compile-time interface checking

nest · Dec 1, 2023 · 25352a8 · 25352a8
1 parent 50c00b8
commit 25352a8
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Showing 3 changed files with 33 additions and 18 deletions.
diff --git a/nestkernel/connection.h b/nestkernel/connection.h
@@ -128,14 +128,6 @@ class Connection
   Connection( const Connection< targetidentifierT >& rhs ) = default;
   Connection& operator=( const Connection< targetidentifierT >& rhs ) = default;
 
-  /**
-   * Get a pointer to an instance of a SecondaryEvent if this connection supports secondary events.
-   *
-   * To prevent erronous calls of this function on primary connections, the base class implementation
-   * below just contains `assert(false)`.
-   */
-  SecondaryEvent* get_secondary_event();
-
   /**
    * Get all properties of this connection and put them into a dictionary.
    */
@@ -398,13 +390,6 @@ Connection< targetidentifierT >::trigger_update_weight( const size_t,
   throw IllegalConnection( "Connection does not support updates that are triggered by a volume transmitter." );
 }
 
-template < typename targetidentifierT >
-SecondaryEvent*
-Connection< targetidentifierT >::get_secondary_event()
-{
-  assert( false );
-}
-
 } // namespace nest
 
 #endif /* CONNECTION_H */
diff --git a/nestkernel/connector_model.h b/nestkernel/connector_model.h
@@ -59,6 +59,26 @@ enum class ConnectionModelProperties : unsigned
   REQUIRES_CLOPATH_ARCHIVING = 1 << 6,
   REQUIRES_URBANCZIK_ARCHIVING = 1 << 7
 };
+}
+
+namespace
+{ // FIXME: utils namespace?
+
+template < typename, typename = void >
+struct has_get_secondary_event_t : std::false_type
+{};
+
+template < typename ConnectionT >
+struct has_get_secondary_event_t<
+    ConnectionT,
+    std::void_t<
+        decltype( std::declval< ConnectionT >().get_secondary_event( ) ) > > : public std::true_type
+{};
+
+} // end of FIXME
+
+namespace nest
+{
 
 template <>
 struct EnableBitMaskOperators< ConnectionModelProperties >
@@ -199,7 +219,16 @@ class GenericConnectorModel : public ConnectorModel
   SecondaryEvent*
   get_secondary_event() override
   {
-    return default_connection_.get_secondary_event();
+    constexpr bool is_primary = flag_is_set( ConnectionT::properties, nest::ConnectionModelProperties::IS_PRIMARY );
+    constexpr bool has_get_secondary_event = has_get_secondary_event_t< ConnectionT >::value;
+    static_assert( is_primary xor has_get_secondary_event,
+      "Non-primary connections have to provide get_secondary_event()" );
+    if constexpr ( ( not is_primary ) and has_get_secondary_event ) {
+      return default_connection_.get_secondary_event();
+    } else {
+      // unreachable code
+      return nullptr;
+    }
   }
 
   ConnectionT const&

diff --git a/nestkernel/connector_model_impl.h b/nestkernel/connector_model_impl.h
@@ -68,8 +68,9 @@ GenericConnectorModel< ConnectionT >::clone( std::string name, synindex syn_id )
   ConnectorModel* new_cm = new GenericConnectorModel( *this, name ); // calls copy construtor
   new_cm->set_syn_id( syn_id );
 
-  const bool is_primary = new_cm->has_property( ConnectionModelProperties::IS_PRIMARY );
-  if ( not is_primary )
+  constexpr bool is_primary = flag_is_set( ConnectionT::properties, nest::ConnectionModelProperties::IS_PRIMARY );
+  constexpr bool has_get_secondary_event = has_get_secondary_event_t< ConnectionT >::value;
+  if constexpr ( ( not is_primary ) and has_get_secondary_event )
   {
     new_cm->get_secondary_event()->add_syn_id( syn_id );
   }