EnTT v3.7.0 changelog preview

[skypjack]

Changelog

• core:
  • Added support for non-copyable types to any.
  • Standard containers friendly is_equality_comparable trait.
  • Added type_list_diff[_t] trait.
  • Added any::reset().
  • Copying an any always returns a copy of the contained object, even in case of references to external elements.
  • Added is_std_hashable[_v] trait.
  • type_id<T>() is a [[nodiscard]] function now.
  • any::as_ref is a member function rather than an in-class friend function exported in the global namespace.
  • basic_any supports configurable sbo size, any is an alias for basic_any<sizeof(double[2])>.
  • Added eventually constexpr conversion operator to underlying type to type_seq.
  • Added eventually constexpr conversion operator to underlying type to type_hash.
  • Added eventually constexpr conversion operator to underlying type to type_name.
  • basic_any takes now in consideration implicit alignment requirements for in_situ tests.
  • Added an extra parameter to basic_any to specify desired alignment requirements for the SBO storage.
• entity:
  • Avoid UB with sparse_set::clear and component-less registry::clear.
  • Use entt::any to store context variables in a registry.
  • registry::storage returns actual references (eventually const) to the poly storage objects.
  • Added basic_sparse_set<E>::at to get entities at given positions.
  • Stable virtual remove for sparse sets.
  • Poly storage no longer has a remove member function by default.
  • Faster registry::clear that delegates to pools.
  • Added optional user data to basic_sparse_set<E>::remove and basic_sparse_set<E>::clear.
  • Simplified sigh_storage_mixin, less instantiations, less code, same functionalities.
  • Added unchecked basic_sparse_set<E>::operator[](pos).
  • Added support to aliased context variables (externally managed objects attached to a registry by reference).
  • Added an operator| to views for piping that creates a new view rather than a view pack.
  • Non-allocating non-const registry::try_get.
• meta:
  • Implicitly generated default meta constructors for default constructible types.
  • Pointer-like to void support (dereference to invalid meta_any).
  • All overloads of meta_type::base return instances of meta_type now.
  • User defined getters are detected as are data members (is_invocable<F, [const] T &> instead of is_invocable<F, [const] T *>).
  • as_ref_t adapts to the constness of the underlying object/return type, as_cref_t always returns by const reference.
  • Added meta_any::reset().
  • Internal utilities (like meta_function_descriptor and meta_invoke) are now public for use as needed.
  • Support for std::vector<bool> and the like as meta containers.
  • Added support for self-pointers and proxy pointers to meta_any when used as pointer-like types.
  • Added explicit const meta_handle::operator bool().
  • Copying a meta_any always returns a copy of the contained object, even in case of references to external elements.
  • Added minimal customizable class template detection support to meta_type (see for example is_template_specialization).
  • meta_any::operator== is now consistent across boundaries.
  • meta_any::as_ref is a member function rather than an in-class friend function exported in the global namespace.
  • Re-registering meta objects is safe in all cases unless the meta objects has a name and the id is already used by a different element (hard user error).
  • A meta_prop key is now returned by const reference rather than by copy.
  • Removed has_meta_sequence_container_traits[_v] and has_meta_associative_container_traits[_v].
  • Meta destructors are no longer invoked for non-owning meta_any objects.
• resource:
  • Removed the requirement for shared_ptr<T> from the loader/cache.
• poly:
  • Added poly::reset().
  • Copying a poly always returns a copy of the contained object, even in case of references to external elements.
  • poly<T>::as_ref is a member function rather than an in-class friend function exported in the global namespace.
  • poly supports configurable sbo size with a default of sizeof(double[2]).
  • Added an extra parameter to poly to specify desired alignment requirements for the underlying storage.
• signal:
  • Made dispatcher class work fine with std::is_copy_constructible.
• Build system:
  • Updated Bazel configuration.
  • Added pkg-config support upon installation.
  • Use lcov for code coverage on the CI.

Bug fixes

• entity:
  • Fixed an issue with registry::clear. There are two ways to get around it in v3.6.x:
    • registry.each([&](auto entity) { registry.destroy(entity); }); if interested in signals.
    • registry = {}; if not interested in signals.

Breaking changes

• core:
  • In-place construction of references in any requires the argument to be an actual lvalue reference and not a pointer.
  • Copying an any always returns a copy of the contained object, even in case of references to external elements. Move the any object, pass it by reference or use as_ref to propagate elements without copying them.
  • Free function as_ref no longer exists for any, use any::as_ref() instead.
  • ENTT_PAGE_SIZE sets the number of elements of a page, not the size in bytes.
• entity:
  • Removed registry::raw<T>(), use registry.view<T>().raw() instead.
  • Removed registry::data<T>(), use registry.view<T>().data() instead.
  • Updated precondition of registry::assign (all pools empty -> no entities still alive).
  • Renamed registry::has<T...> to registry::all_of<T...> and registry::any<T...> to registry::any_of<T...>.
  • Renamed handle::has<T...> to handle::all_of<T...> and handle::any<T...> to handle::any_of<T...>.
  • registry::storage returns poly storage objects by reference rather than by copy. Capture them by reference before using.
  • Poly storage no longer has a remove member function by default.
  • Const registry::view is no longer thread safe.
• meta:
  • Removed meta_conv, it's used internally when needed (eg meta_any::allow_cast).
  • Removed meta_base, it's used internally when needed (eg meta_any::cast).
  • All overloads of meta_type::base return instances of meta_type now.
  • Meta iterators for associative containers return keys as const references and no longer by copy.
  • meta_handle::operator* isn't available anymore, no alternatives provided.
  • Copying a meta_any always returns a copy of the contained object, even in case of references to external elements. Move the meta_any object, pass it by reference or use as_ref to propagate elements without copying them.
  • Renamed meta_ctor::size and meta_func::size to meta_ctor::arity and meta_func::arity.
  • Deleted meta_handle copy constructor. No alternatives provided. Meta handles should never be copied.
  • Free function as_ref no longer exists for meta_any, use meta_any::as_ref() instead.
  • Removed has_meta_sequence_container_traits[_v] , use entt::is_complete_v<entt::meta_sequence_container_traits<T>> instead.
  • Removed has_meta_associative_container_traits[_v], use entt::is_complete_v<entt::meta_sequence_associative_traits<T>> instead.
• poly:
  • Copying a poly always returns a copy of the contained object, even in case of references to external elements. Move the poly object, pass it by reference or use as_ref to propagate elements without copying them.
  • Free function as_ref no longer exists for poly<T>, use poly<T>::as_ref() instead.

Any other business

The documentation is up-to-date and the library is battle-tested with 100% coverage as usual.
I've also updated the section EnTT in Action with more and more examples.

I started a long term process to reduce the number of instantiations and therefore speed up the compilation.
This release contains some more changes in this regard. Still a work in progress though.

[LiliumAtratum]

There is nothing to see here yet. 🙂

Troll! 😄

[skypjack]

Well, it's the weekend, gimme the time to start adding some lines there. 😄

Any suggestions in the meantime? A short list of the first things on which I plan to work:

• Default constructors automatically registered in meta (so that ie we don't have to reflect primitive types explicitly).
• Storage pagination, so that component additions won't invalidate references anymore.
• Documentation for the custom storage (it could help actually 😄).
• Finish the work to decouple sequential identifiers and component identifiers, so that working across boundaries won't require anymore the user to write the code for that.
• Make groups a custom storage and remove the group class as well as the registry::group* functions.
• More on multi-threading. It's something on which I'm working and many things will change in future in this sense.
• Optional destroy chain (to speed up the destroy of an entity, it's an already tested feature that I've to port to the public repo but it's admittedly not top priority at the moment).

Comments or feedback?

[LiliumAtratum]

multi-threading is definetely something that picks my interest. But I think it is big, not only on the implementation side, but also on the general application architecture when using ECS, and it deserves its own topic.

[Green-Sky]

Documentation for the custom storage

yes please 😄

[skypjack]

Release available upstream. 👍 🥳