pub trait NoneValue {
type NoneType;
fn null_value() -> Self::NoneType;
}
Expand description
Type that uses a special value to be used as none.
See Optional
documentation for the rationale for this trait’s existence.
Caveats
Since use of default values as none is typical, this trait is implemented for all types that
implement Default
for convenience. Unfortunately, this means you can not implement this
trait manually for types that implement Default
.
Required Associated Types
Required Methods
fn null_value() -> Self::NoneType
fn null_value() -> Self::NoneType
The none-equivalent value.