This change aims to reduce the number of places that need to be changed
when adding or editing a Godot type to the bindings.
Since the addition of `Variant.From<T>/As<T>` and
`VariantUtils.CreateFrom<T>/ConvertTo<T>`, we can now replace a lot of
the previous code in the bindings generator and the source generators
that specify these conversions for each type manually.
The only exceptions are the generic Godot collections (`Array<T>` and
`Dictionary<TKey, TValue>`) which still use the old version, as that
one cannot be matched by our new conversion methods (limitation in the
language with generics, forcing us to use delegate pointers).
The cleanup applies to:
- Bindings generator:
- `TypeInterface.cs_variant_to_managed`
- `TypeInterface.cs_managed_to_variant`
- Source generators:
- `MarshalUtils.AppendNativeVariantToManagedExpr`
- `MarshalUtils.AppendManagedToNativeVariantExpr`
- `MarshalUtils.AppendVariantToManagedExpr`
- `MarshalUtils.AppendManagedToVariantExpr`
This commit replaces most usages of `ConvertManagedObjectToVariant` and
`ConvertVariantToManagedObjectOfType`, by using the `Godot.Variant`
struct instead of `System.Object`.
The most notable change is to the `GetGodotPropertyDefaultValues` method
that's generated for scripts. The dictionary it returns now stores
`Godot.Variant` values.
Remaining usages are:
- The `DelegateUtils` class, for the serialization of closure display
classes during assembly reloading by the editor. These display classes
are compiler generated classes to store values captured by a closure.
Since it's generated by the compiler, the only way we have to access
the fields is through reflection. This leads to using `System.Object`.
- Converting parameters when invoking constructors from the engine.
This will be replaced with source generators in the future.
- Legacy support for old `GetGodotPropertyDefaultValues` return values.
We need to keep supporting the old version of this generated method
for some time. Otherwise, if loading a project built with the previous
version, it could lead to the loss of exported property values.
Ideally, we should remove this legacy support before a stable release.
Its two usages were:
- The Array `ICollection.CopyTo` implementation.
It's possible that this class shouldn't be implementing the
non-generic `ICollection`, but this commit doesn't change that.
The new implementation stores the elements as boxed `Variant` values.
- The `Variant.Obj` property.
I'm not sure if this property's existence is justified, but for now
I rewrote it as a simpler version of `ConvertVariantToManagedObject`.
Update the docs to clarify that the `@icon` annotation does not work
when only attaching a script to a node, and clarify that the script itself
must be a globally accessible script type.
