pub unsafe trait DefaultBoxed {
    unsafe fn default_in_place(ptr: *mut Self);

    fn default_boxed() -> Box<Self>
        Self: Sized
, { ... }
fn default_boxed_array<const N: usize>() -> Box<[Self; N]>
        Self: Sized
, { ... } }
Expand description

Helper trait to create a boxed instance of the given type with a default value for each field.

This trait can be derived for structs.

To derive this trait, each field needs to also implement this trait, but all types which implements Default implements this trait via the blanket impl already.

In addition, if a field is an array, only the item type needs to implement this trait, and each item would be initialized separately.


Implementations must ensure that default_in_place initializes the value on the given pointer.

Required methods

Fill the given memory location with default value.


For callers, behavior is undefined if ptr is not valid for writes, or it is not properly aligned.

For impls, behavior is undefined if this method reads from ptr.

Provided methods

Create a boxed instance with default value for each field.

Create a boxed array of the given size with default value of the type.

use default_boxed::DefaultBoxed;
let arr = u32::default_boxed_array::<32>();
assert_eq!(arr, Box::new([0; 32]));