Trait objc2::foundation::NSCopying
source · pub unsafe trait NSCopying: Message {
type Ownership: Ownership;
type Output: Message;
// Provided method
fn copy(&self) -> Id<Self::Output, Self::Ownership> { ... }
}Required Associated Types§
sourcetype Ownership: Ownership
type Ownership: Ownership
Indicates whether the type is mutable or immutable.
This can be Owned if and only if copy creates a new instance,
see the following example:
ⓘ
let x: Id<MyObject, _> = MyObject::new();
// This is valid only if `y` is a new instance. Otherwise `x` and `y`
// would be able to create aliasing mutable references!
let y: Id<MyObject, Owned> = x.copy();Note that for the same reason, you should be careful when defining
new methods on your object; e.g. immutable types like NSString
don’t return Id<NSString, Owned>, because that would allow this
trait to create an aliasing Id<NSString, Shared> (since sending the
copy message (and others) does not create a new instance, but
instead just retains the instance).
Provided Methods§
Implementors§
source§impl NSCopying for NSAttributedString
impl NSCopying for NSAttributedString
source§impl NSCopying for NSException
impl NSCopying for NSException
This is implemented as a shallow copy.
As such, it is only possible when the array’s contents are Shared.