core::nullable::NullableTrait

Signature

pub trait NullableTrait

Trait functions

deref

Wrapper for Deref::deref. Prefer using Deref::deref directly. This function exists for backwards compatibility.

Signature

fn deref(nullable: Nullable) -> T

Examples

Preferred way:

let value: Nullable = NullableTrait::new(42);
let unwrapped = value.deref();

This function method does the same thing:

use core::nullable::NullableTrait;
let also_unwrapped = NullableTrait::deref(value);

deref_or

Returns the contained value if not null, or returns the provided default value.

Signature

fn deref_or>(self: Nullable, default: T) -> T

Examples

let value: Nullable = NullableTrait::new(42);
assert!(value.deref_or(0) == 42);

let null_value: Nullable = Default::default();
assert!(null_value.deref_or(0) == 0);

deref_or_else

Returns the contained value if not null, or computes it from a closure.

Signature

fn deref_or_else, impl func: FnOnce, +Drop>(
    self: Nullable, f: F,
) -> T

Examples

let value: Nullable = NullableTrait::new(42);
assert!(value.deref_or_else(|| 0) == 42);

let null_value: Nullable = Default::default();
assert!(null_value.deref_or_else(|| 0) == 0);

new

Creates a new non-null Nullable with the given value.

Signature

fn new(value: T) -> Nullable

Examples

let value: Nullable = NullableTrait::new(42);
assert!(!value.is_null());

is_null

Returns true if the value is null.

Signature

fn is_null(self: @Nullable) -> bool

Examples

let value: Nullable = NullableTrait::new(42);
assert!(!value.is_null());

let null_value: Nullable = Default::default();
assert!(null_value.is_null());

as_snapshot

Creates a new Nullable containing a snapshot of the value. This is useful when working with non-copyable types inside a Nullable. This allows you to keep using the original value while also having access to a snapshot of it, preventing the original value from being moved.

Signature

fn as_snapshot(self: @Nullable) -> Nullable

Examples

let value: Nullable> = NullableTrait::new(array![1, 2, 3]);
let res = (@value).as_snapshot();
assert!(res.deref() == @array![1, 2, 3]);
assert!(value.deref() == array![1, 2, 3]);