diff --git a/libs/ecs/include/psemek/ecs/entity_container.hpp b/libs/ecs/include/psemek/ecs/entity_container.hpp
index 0e751bc7..a86c7a24 100644
--- a/libs/ecs/include/psemek/ecs/entity_container.hpp
+++ b/libs/ecs/include/psemek/ecs/entity_container.hpp
@@ -15,93 +15,37 @@ namespace psemek::ecs
 
 	struct entity_container
 	{
+		// Create an entity with the specified components
+		// NB: equivalent to create() followed by a
+		// series of attach() calls, but faster
 		template <typename ... Components>
-		entity_handle create(Components && ... components)
-		{
-			detail::component_uuid_holder<Components...> uuids;
-			detail::component_mask mask = component_index_.make_component_mask(uuids.get());
+		entity_handle create(Components && ... components);
 
-			auto insert_result = table_container_.insert<Components...>(mask, uuids.get());
-			auto table = insert_result.first;
-			bool created = insert_result.second;
+		// Check if an entity handle refers to an active entity
+		// UB if the handle wasn't obtained by a create() call
+		bool alive(entity_handle const & entity) const;
 
-			if (created)
-			{
-				query_cache_container_.apply([table](detail::query_cache & cache){
-					cache.add(table);
-				}, mask);
-			}
+		// Destroy an entity
+		// UB if the handle wasn't obtained by a create() call
+		// or if the entity was already destroyed
+		void destroy(entity_handle const & entity);
 
-			auto id = entity_list_.create(table, table->row_count());
-			entity_handle handle{id, entity_list_.get_entities()[id].epoch};
-			[[maybe_unused]] entity_accessor accessor = get(handle);
-
-			table->push_row(id);
-			((accessor.get<Components>() = std::move(components)), ...);
-
-			return handle;
-		}
-
-		bool alive(entity_handle const & entity) const
-		{
-			return entity_list_.get_entities()[entity.id].epoch == entity.epoch;
-		}
-
-		void destroy(entity_handle const & entity)
-		{
-			// Swap with the last row in that table
-			auto entities = entity_list_.get_entities();
-			auto & data = entities[entity.id];
-			auto table_entity_ids = data.table->get_entity_ids();
-			data.table->swap_rows(data.row, table_entity_ids.size() - 1);
-			data.table->pop_row();
-			auto swap_id = table_entity_ids[data.row];
-			auto & swap_data = entities[swap_id];
-			swap_data.row = data.row;
-			entity_list_.destroy(entity.id);
-		}
+		// Get an entity accessor for an entity
+		// UB if the handle wasn't obtained by a create() call
+		// or if the entity isn't active
+		entity_accessor get(entity_handle const & entity);
 
+		// Create a query cache that can be used for the
+		// apply() call to speed it up
 		template <typename ... Components>
-		query_cache cache()
-		{
-			detail::component_uuid_holder<Components...> uuids;
-			detail::component_mask mask = component_index_.make_component_mask(uuids.get());
-
-			auto result = query_cache_container_.create(mask, uuids.get());
-
-			table_container_.apply([&](detail::table & table){
-				result->add(&table);
-			}, mask);
-
-			return result;
-		}
+		query_cache cache();
 
+		// Apply a function to all entities having the specified
+		// components. The function signature is void(entity_handle, components...)
+		// An optional query cache can be supplied to speed up the call
+		// UB if the cache wasn't created with the exact same component sequence
 		template <typename ... Components, typename Function>
-		void apply(Function && function, query_cache cache = {})
-		{
-			if (!cache)
-				cache = this->cache<Components...>();
-
-			for (auto const & entry : cache->tables)
-			{
-				detail::static_apply_helper<Components...> apply_helper(entry.table->get_entity_ids(), entity_list_.get_entities());
-
-				for (std::size_t i = 0; i < sizeof...(Components); ++i)
-					apply_helper.pointers[i] = entry.table->get_component_pointers()[entry.column_ids[i]];
-
-				for (std::size_t i = 0; i < apply_helper.size(); ++i)
-				{
-					apply_helper.apply(function);
-					apply_helper.advance();
-				}
-			}
-		}
-
-		entity_accessor get(entity_handle const & entity)
-		{
-			auto const & data = entity_list_.get_entities()[entity.id];
-			return {data.table, data.row};
-		}
+		void apply(Function && function, query_cache cache = {});
 
 	private:
 		detail::entity_list entity_list_;
@@ -110,4 +54,66 @@ namespace psemek::ecs
 		detail::query_cache_container query_cache_container_;
 	};
 
+	template <typename ... Components>
+	entity_handle entity_container::create(Components && ... components)
+	{
+		detail::component_uuid_holder<Components...> uuids;
+		detail::component_mask mask = component_index_.make_component_mask(uuids.get());
+
+		auto insert_result = table_container_.insert<Components...>(mask, uuids.get());
+		auto table = insert_result.first;
+		bool created = insert_result.second;
+
+		if (created)
+		{
+			query_cache_container_.apply([table](detail::query_cache & cache){
+				cache.add(table);
+			}, mask);
+		}
+
+		auto id = entity_list_.create(table, table->row_count());
+		entity_handle handle{id, entity_list_.get_entities()[id].epoch};
+		[[maybe_unused]] entity_accessor accessor = get(handle);
+
+		table->push_row(id);
+		((accessor.get<Components>() = std::move(components)), ...);
+
+		return handle;
+	}
+
+	template <typename ... Components>
+	query_cache entity_container::cache()
+	{
+		detail::component_uuid_holder<Components...> uuids;
+		detail::component_mask mask = component_index_.make_component_mask(uuids.get());
+
+		auto result = query_cache_container_.create(mask, uuids.get());
+
+		table_container_.apply([&](detail::table & table){
+			result->add(&table);
+		}, mask);
+
+		return result;
+	}
+
+	template <typename ... Components, typename Function>
+	void entity_container::apply(Function && function, query_cache cache)
+	{
+		if (!cache)
+			cache = this->cache<Components...>();
+
+		for (auto const & entry : cache->tables)
+		{
+			detail::static_apply_helper<Components...> apply_helper(entry.table->get_entity_ids(), entity_list_.get_entities());
+
+			for (std::size_t i = 0; i < sizeof...(Components); ++i)
+				apply_helper.pointers[i] = entry.table->get_component_pointers()[entry.column_ids[i]];
+
+			for (std::size_t i = 0; i < apply_helper.size(); ++i)
+			{
+				apply_helper.apply(function);
+				apply_helper.advance();
+			}
+		}
+	}
 }
diff --git a/libs/ecs/source/entity_container.cpp b/libs/ecs/source/entity_container.cpp
new file mode 100644
index 00000000..94324933
--- /dev/null
+++ b/libs/ecs/source/entity_container.cpp
@@ -0,0 +1,31 @@
+#include <psemek/ecs/entity_container.hpp>
+
+namespace psemek::ecs
+{
+
+	bool entity_container::alive(entity_handle const & entity) const
+	{
+		return entity_list_.get_entities()[entity.id].epoch == entity.epoch;
+	}
+
+	void entity_container::destroy(entity_handle const & entity)
+	{
+		// Swap with the last row in that table
+		auto entities = entity_list_.get_entities();
+		auto & data = entities[entity.id];
+		auto table_entity_ids = data.table->get_entity_ids();
+		data.table->swap_rows(data.row, table_entity_ids.size() - 1);
+		data.table->pop_row();
+		auto swap_id = table_entity_ids[data.row];
+		auto & swap_data = entities[swap_id];
+		swap_data.row = data.row;
+		entity_list_.destroy(entity.id);
+	}
+
+	entity_accessor entity_container::get(entity_handle const & entity)
+	{
+		auto const & data = entity_list_.get_entities()[entity.id];
+		return {data.table, data.row};
+	}
+
+}