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meta: deprecate meta properties in favor of custom data

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This commit is contained in:
Michele Caini
2024-09-10 16:12:28 +02:00
parent 355010df3b
commit e4ba5c31d2
4 changed files with 9 additions and 61 deletions
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1
TODO
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@@ -32,7 +32,6 @@ TODO:
* cleanup common view from tricks to handle single swap-only and in-place, if constexpr branches
* entity based component_traits
* review cmake warning about FetchContent_Populate (need .28 and EXCLUDE_FROM_ALL for FetchContent)
* deprecate meta properties in favor of custom data
* make meta objects safe to use with null nodes
* suppress -Wself-move on CI with g++13
* view and view iterator specializations for multi, single and filtered elements

53
docs/md/meta.md
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@@ -16,7 +16,6 @@
* [Policies: the more, the less](#policies-the-more-the-less)
* [Named constants and enums](#named-constants-and-enums)
* [User defined data](#user-defined-data)
* [Properties and meta objects](#properties-and-meta-objects)
* [Traits](#traits)
* [Custom data](#custom-data)
* [Unregister types](#unregister-types)
@@ -841,15 +840,10 @@ object optimization performed by the `meta_any` class.
## User defined data
Sometimes (for example, when it comes to creating an editor) it might be useful
to attach _properties_, _traits_ or arbitrary _custom data_ to the meta objects
created.
to attach _traits_ or arbitrary _custom data_ to the meta objects created.
The main difference between them is that:
* Properties are usually key-only or key-value pairs with lower access
performance. They are deprecated today but have long been the only way to
bind user data with meta objects.
* Traits are simple user-defined flags with much higher access performance. The
library reserves up to 16 bits for traits, that is 16 flags for a bitmask or
2^16 values otherwise.
@@ -860,51 +854,6 @@ The main difference between them is that:
In all cases, this support is currently available only for meta types, meta data
and meta functions.
### Properties and meta objects
Properties are set via a meta factory and are not editable once created:
```cpp
entt::meta<my_type>().prop("tooltip"_hs, "message");
```
They are always in the key/value form. The key is a numeric identifier, mostly
similar to the identifier used to register meta objects. There are no
restrictions on the type of the value instead, as long as it's movable.<br/>
Key only properties are also supported out of the box:
```cpp
entt::meta<my_type>().prop(my_enum::key_only);
```
To attach multiple properties to a meta object, just invoke `prop` more than
once.<br/>
It's also possible to call `prop` at different times, as long as the factory is
reset to the meta object of interest:
```cpp
entt::meta<my_type>()
.data<&my_type::data_member, entt::as_ref_t>("member"_hs)
.prop("key"_hs, value);
```
Once created, all meta objects offer a couple of member functions named `prop`
to iterate all properties at once or to search a specific property by key:
```cpp
// iterate all properties of a meta type
for(auto &&[id, prop]: entt::resolve<my_type>().prop()) {
// ...
}
// search for a given property by name
auto prop = entt::resolve<my_type>().prop("tooltip"_hs);
```
Meta properties are objects having a fairly poor interface, all in all. They
only provide the `value` member function to retrieve the contained value in the
form of a `meta_any` object.
### Traits
User-defined traits are set via a meta factory:

2
src/entt/meta/factory.hpp
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@@ -498,7 +498,7 @@ public:
* @return A meta factory for the parent type.
*/
template<typename... Value>
meta_factory prop(id_type id, [[maybe_unused]] Value &&...value) {
[[deprecated("use ::custom() instead")]] meta_factory prop(id_type id, [[maybe_unused]] Value &&...value) {
if constexpr(sizeof...(Value) == 0u) {
base_type::prop(internal::meta_prop_node{id, &internal::resolve<void>});
} else {

14
src/entt/meta/meta.hpp
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@@ -765,7 +765,7 @@ private:
};
/*! @brief Opaque wrapper for properties of any type. */
struct meta_prop {
struct [[deprecated("use meta_custom instead")]] meta_prop {
/*! @brief Default constructor. */
meta_prop() noexcept = default;
@@ -938,7 +938,7 @@ struct meta_data {
* @brief Returns a range to visit registered meta properties.
* @return An iterable range to visit registered meta properties.
*/
[[nodiscard]] meta_range<meta_prop, typename decltype(internal::meta_data_node::prop)::const_iterator> prop() const noexcept {
[[nodiscard]] [[deprecated("use ::custom() instead")]] meta_range<meta_prop, typename decltype(internal::meta_data_node::prop)::const_iterator> prop() const noexcept {
return {{*ctx, node->prop.cbegin()}, {*ctx, node->prop.cend()}};
}
@@ -947,7 +947,7 @@ struct meta_data {
* @param key The key to use to search for a property.
* @return The registered meta property for the given key, if any.
*/
[[nodiscard]] meta_prop prop(const id_type key) const {
[[nodiscard]] [[deprecated("use ::custom() instead")]] meta_prop prop(const id_type key) const {
for(auto &&elem: node->prop) {
if(elem.id == key) {
return meta_prop{*ctx, elem};
@@ -1083,7 +1083,7 @@ struct meta_func {
}
/*! @copydoc meta_data::prop */
[[nodiscard]] meta_range<meta_prop, typename decltype(internal::meta_func_node::prop)::const_iterator> prop() const noexcept {
[[nodiscard]] [[deprecated("use ::custom() instead")]] meta_range<meta_prop, typename decltype(internal::meta_func_node::prop)::const_iterator> prop() const noexcept {
return {{*ctx, node->prop.cbegin()}, {*ctx, node->prop.cend()}};
}
@@ -1092,7 +1092,7 @@ struct meta_func {
* @param key The key to use to search for a property.
* @return The registered meta property for the given key, if any.
*/
[[nodiscard]] meta_prop prop(const id_type key) const {
[[nodiscard]] [[deprecated("use ::custom() instead")]] meta_prop prop(const id_type key) const {
for(auto &&elem: node->prop) {
if(elem.id == key) {
return meta_prop{*ctx, elem};
@@ -1562,7 +1562,7 @@ public:
* @brief Returns a range to visit registered top-level meta properties.
* @return An iterable range to visit registered top-level meta properties.
*/
[[nodiscard]] meta_range<meta_prop, typename decltype(internal::meta_type_descriptor::prop)::const_iterator> prop() const noexcept {
[[nodiscard]] [[deprecated("use ::custom() instead")]] meta_range<meta_prop, typename decltype(internal::meta_type_descriptor::prop)::const_iterator> prop() const noexcept {
using range_type = meta_range<meta_prop, typename decltype(internal::meta_type_descriptor::prop)::const_iterator>;
return node.details ? range_type{{*ctx, node.details->prop.cbegin()}, {*ctx, node.details->prop.cend()}} : range_type{};
}
@@ -1572,7 +1572,7 @@ public:
* @param key The key to use to search for a property.
* @return The registered meta property for the given key, if any.
*/
[[nodiscard]] meta_prop prop(const id_type key) const {
[[nodiscard]] [[deprecated("use ::custom() instead")]] meta_prop prop(const id_type key) const {
const auto *elem = internal::look_for<&internal::meta_type_descriptor::prop>(internal::meta_context::from(*ctx), node, key);
return elem ? meta_prop{*ctx, *elem} : meta_prop{};
}