Trait Length 

pub trait Length {
    type Count: Display + Truthy;

    // Required method
    fn length(&self) -> Self::Count;
}

How many items {{ rows.length }} reports.

This follows handlebars.js, where length is an ordinary property lookup and a JS array carries one. Only lists have it here: a String deliberately does not, because JS counts UTF-16 code units and Rust would count either bytes or chars — all three disagree on the same text, and a quietly different number is exactly what this crate promises never to produce.

Count is an associated type rather than a plain usize so that a list which was never set can report nothing at all, as an undefined value does in handlebars.js, while a list with no items in it reports 0.

Required Associated Types

type Count: Display + Truthy

What the count renders as: a number, or nothing at all when the list was never set.

Required Methods

fn length(&self) -> Self::Count

How many items this holds.

Dyn Compatibility

This trait is dyn compatible.

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

Implementations on Foreign Types

impl<T, const N: usize> Length for [T; N]

type Count = usize

fn length(&self) -> usize

impl<T: Length + ?Sized> Length for &T

type Count = <T as Length>::Count

fn length(&self) -> T::Count

impl<T> Length for Vec<T>

type Count = usize

fn length(&self) -> usize

impl<T> Length for [T]

type Count = usize

fn length(&self) -> usize

Implementors

impl Length for Empty

A variable that was never set is absent, and absent has no count — {{ rows.length }} writes nothing, rather than 0, exactly as it does for an undefined value in handlebars.js.

type Count = Empty

impl<T> Length for Absent<T>

type Count = Empty