Why do I not have to implement the Any trait for a type even though it is a required?
When defining a trait, my understanding is that trait names on the right side of the : are required any time the left side is implemented. If so, why does the following compile:
use std::any::Any;
trait Trait: Any
struct Thing
impl Trait for Thing
The following does not compile (which matches my understanding of what is correct)
trait RequiredTrait
trait Trait: RequiredTrait
struct Thing
impl Trait for Thing
rust
edited Nov 15 '18 at 16:07
Shepmaster
154k14306446
asked Nov 14 '18 at 22:56
Aakil FernandesAakil Fernandes
3,58232040
add a comment |
When defining a trait, my understanding is that trait names on the right side of the : are required any time the left side is implemented. If so, why does the following compile:
use std::any::Any;
trait Trait: Any
struct Thing
impl Trait for Thing
The following does not compile (which matches my understanding of what is correct)
trait RequiredTrait
trait Trait: RequiredTrait
struct Thing
impl Trait for Thing
rust
edited Nov 15 '18 at 16:07
Shepmaster
154k14306446
asked Nov 14 '18 at 22:56
Aakil FernandesAakil Fernandes
3,58232040
add a comment |
When defining a trait, my understanding is that trait names on the right side of the : are required any time the left side is implemented. If so, why does the following compile:
use std::any::Any;
trait Trait: Any
struct Thing
impl Trait for Thing
The following does not compile (which matches my understanding of what is correct)
trait RequiredTrait
trait Trait: RequiredTrait
struct Thing
impl Trait for Thing
rust
edited Nov 15 '18 at 16:07
Shepmaster
154k14306446
asked Nov 14 '18 at 22:56
Aakil FernandesAakil Fernandes
3,58232040
When defining a trait, my understanding is that trait names on the right side of the : are required any time the left side is implemented. If so, why does the following compile:
use std::any::Any;
trait Trait: Any
struct Thing
impl Trait for Thing
The following does not compile (which matches my understanding of what is correct)
trait RequiredTrait
trait Trait: RequiredTrait
struct Thing
impl Trait for Thing
rust
rust
edited Nov 15 '18 at 16:07
Shepmaster
154k14306446
asked Nov 14 '18 at 22:56
Aakil FernandesAakil Fernandes
3,58232040
edited Nov 15 '18 at 16:07
Shepmaster
154k14306446
asked Nov 14 '18 at 22:56
Aakil FernandesAakil Fernandes
3,58232040
edited Nov 15 '18 at 16:07
Shepmaster
154k14306446
edited Nov 15 '18 at 16:07
Shepmaster
154k14306446
edited Nov 15 '18 at 16:07
Shepmaster
154k14306446
154k14306446
asked Nov 14 '18 at 22:56
Aakil FernandesAakil Fernandes
3,58232040
asked Nov 14 '18 at 22:56
Aakil FernandesAakil Fernandes
3,58232040
asked Nov 14 '18 at 22:56
Aakil FernandesAakil Fernandes
3,58232040
3,58232040
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
std::any contains the implementation:
impl<T> Any for T
where
T: 'static + ?Sized,
That means that any type implements Any as long as any references it contains are 'static and the type is sized. Your Thing struct meets both of those requirements so it does implement Any and your code compiles.
edited Nov 15 '18 at 16:09
Shepmaster
154k14306446
answered Nov 14 '18 at 23:03
sepp2ksepp2k
296k38596613
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
std::any contains the implementation:
impl<T> Any for T
where
T: 'static + ?Sized,
That means that any type implements Any as long as any references it contains are 'static and the type is sized. Your Thing struct meets both of those requirements so it does implement Any and your code compiles.
edited Nov 15 '18 at 16:09
Shepmaster
154k14306446
answered Nov 14 '18 at 23:03
sepp2ksepp2k
296k38596613
add a comment |
std::any contains the implementation:
impl<T> Any for T
where
T: 'static + ?Sized,
That means that any type implements Any as long as any references it contains are 'static and the type is sized. Your Thing struct meets both of those requirements so it does implement Any and your code compiles.
edited Nov 15 '18 at 16:09
Shepmaster
154k14306446
answered Nov 14 '18 at 23:03
sepp2ksepp2k
296k38596613
add a comment |
std::any contains the implementation:
impl<T> Any for T
where
T: 'static + ?Sized,
That means that any type implements Any as long as any references it contains are 'static and the type is sized. Your Thing struct meets both of those requirements so it does implement Any and your code compiles.
edited Nov 15 '18 at 16:09
Shepmaster
154k14306446
answered Nov 14 '18 at 23:03
sepp2ksepp2k
296k38596613
std::any contains the implementation:
impl<T> Any for T
where
T: 'static + ?Sized,
That means that any type implements Any as long as any references it contains are 'static and the type is sized. Your Thing struct meets both of those requirements so it does implement Any and your code compiles.
edited Nov 15 '18 at 16:09
Shepmaster
154k14306446
answered Nov 14 '18 at 23:03
sepp2ksepp2k
296k38596613
edited Nov 15 '18 at 16:09
Shepmaster
154k14306446
edited Nov 15 '18 at 16:09
Shepmaster
154k14306446
edited Nov 15 '18 at 16:09
Shepmaster
154k14306446
154k14306446
answered Nov 14 '18 at 23:03
sepp2ksepp2k
296k38596613
answered Nov 14 '18 at 23:03
sepp2ksepp2k
296k38596613
answered Nov 14 '18 at 23:03
sepp2ksepp2k
296k38596613
296k38596613
add a comment |
add a comment |
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