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* meta_any: convert -> allow_cast
* support for const references
* as_cref_t policy
This commit is contained in:
Michele Caini
2020-12-23 09:42:04 +01:00
parent 3dac65a012
commit c52f16f5b8
11 changed files with 178 additions and 160 deletions
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docs/md/meta.md
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@@ -215,9 +215,9 @@ const bool equal = (any == other);
Also, `meta_any` adds support for containers and pointer-like types (see the
following sections for more details).<br/>
Similar to `any`, this class can also be used to create _aliases_ for unmanaged
objects either upon construction using `std::ref` or from an existing instance
by means of the `as_ref` function. However, unlike `any`,` meta_any` treats an
empty instance and one initialized with `void` differently:
objects either upon construction using `std::ref` and `std::cref` or from an
existing instance by means of the `as_ref` function. However, unlike `any`,
`meta_any` treats an empty instance and one initialized with `void` differently:
```cpp
entt::meta_any empty{};
@@ -228,9 +228,10 @@ While `any` treats both objects as empty, `meta_any` treats objects initialized
with `void` as if they were _valid_ ones. This allows to differentiate between
failed function calls and function calls that are successful but return
nothing.<br/>
Finally, the member functions `try_cast`, `cast` and `convert` are used to know
if the underlying object has a given type as a base or if it can be converted
implicitly to it. There is in fact no `any_cast` equivalent for `meta_any`.
Finally, the member functions `try_cast`, `cast` and `allow_cast` are used to
cast the underlying object to a given type (either a reference or a value type)
or to _convert_ a `meta_any` in such a way that a cast becomes viable for the
resulting object. There is in fact no `any_cast` equivalent for `meta_any`.
## Enjoy the runtime
@@ -684,13 +685,14 @@ There are a few alternatives available at the moment:
entt::meta<my_type>().func<&my_type::member_function, entt::as_void_t>("member"_hs);
```
* The _as-ref_ policy, associated with the type `entt::as_ref_t`.<br/>
It allows to build wrappers that act as references to unmanaged objects.
Modifying the object contained in the wrapper for which the _reference_ was
requested will make it possible to directly modify the instance used to
* The _as-ref_ and _as-cref_ policies, associated with the types
`entt::as_ref_t` and `entt::as_cref_t`.<br/>
They allow to build wrappers that act as references to unmanaged objects.
Accessing the object contained in the wrapper for which the _reference_ was
requested will make it possible to directly access the instance used to
initialize the wrapper itself.<br/>
This policy works with constructors (for example, when objects are taken from
an external container rather than created on demand), data members and
These policies work with constructors (for example, when objects are taken
from an external container rather than created on demand), data members and
functions in general (as long as their return types are lvalue references).
As an example of use: