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core: tag is no longer deprecated (close #457)

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This commit is contained in:
Michele Caini
2020-04-06 23:21:17 +02:00
parent 5a8e46a6b8
commit 8151fbcb2e
2 changed files with 27 additions and 10 deletions
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21
docs/md/core.md
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@@ -20,6 +20,7 @@
* [Type traits](#type-traits)
* [Member class type](#member-class-type)
* [Integral constant](#integral-constant)
* [Tag](#tag)
<!--
@endcond TURN_OFF_DOXYGEN
-->
@@ -223,7 +224,7 @@ specializations such as:
```cpp
template<typename Type>
struct entt::type_info<Type, std::void_d<decltype(Type::custom_id())>> {
static constexpr ENTT_ID_TYPE id() ENTT_NOEXCEPT {
static constexpr entt::id_type id() ENTT_NOEXCEPT {
return Type::custom_id();
}
};
@@ -294,7 +295,7 @@ specializations such as:
```cpp
template<typename Type>
struct entt::type_index<Type, std::void_d<decltype(Type::index())>> {
static id_type value() ENTT_NOEXCEPT {
static entt::id_type value() ENTT_NOEXCEPT {
return Type::index();
}
};
@@ -341,3 +342,19 @@ as human-readable _names_ where actual types would be required otherwise:
constexpr auto enemy_tag = entt::integral_constant<"enemy"_hs>;
registry.emplace<enemy_tag>(entity);
```
### Tag
Since `id_type` is very important and widely used in `EnTT`, there is a more
user-friendly shortcut for the creation of integral constants based on it.<br/>
This shortcut is the alias template `entt::tag`.
If used in combination with hashed strings, it helps to use human-readable names
where types would be required otherwise. As an example:
```cpp
registry.assign<entt::tag<"enemy"_hs>>(entity);
```
However, this isn't the only permitted use. Literally any value convertible to
`id_type` is a good candidate, such as the named constants of an unscoped enum.

16
src/entt/core/type_traits.hpp
View File

@@ -21,6 +21,14 @@ template<auto Value>
using integral_constant = std::integral_constant<decltype(Value), Value>;
/**
* @brief Alias template to ease the creation of named values.
* @tparam Value A constant value at least convertible to `id_type`.
*/
template<id_type Value>
using tag = integral_constant<Value>;
/**
* @brief Utility class to disambiguate overloaded functions.
* @tparam N Number of choices available.
@@ -210,14 +218,6 @@ template<typename Member>
using member_class_t = typename member_class<Member>::type;
/**
* @brief Alias template to ease the creation of named values.
* @tparam Value A constant value at least convertible to `id_type`.
*/
template<id_type Value>
using tag [[deprecated("use entt::integral_constant instead")]] = integral_constant<Value>;
}