Trait Len 

pub trait Len {
    // Required method
    fn len(&self) -> usize;

    // Provided method
    fn is_empty(&self) -> bool { ... }
}

A trait for types that have a notion of length or size.

This trait provides a standard interface for determining the number of elements in a collection or the size of an object. It defines both a required len() method and a default implementation of is_empty() which relies on len().

Types implementing this trait can be checked for emptiness using the is_empty() method without requiring a separate implementation, as long as they provide a way to determine their length.

Required Methods

fn len(&self) -> usize

Returns the number of elements in the collection or the size of the object.

Returns

A usize representing the length or size.

Provided Methods

fn is_empty(&self) -> bool

Returns true if the collection contains no elements or the object has zero size.

Returns

A boolean indicating whether the object is empty.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors