Trait Meter 

pub trait Meter<K, V> {
    type Measure: Default + Copy + Ord + Display + Add<Output = Self::Measure> + Sub<Output = Self::Measure>;

    // Required method
    fn measure<Q: ?Sized>(&self, key: &Q, value: &V) -> Self::Measure
       where K: Borrow<Q>;
}

A trait for measuring the size of a cache item.

Meter is used to provide the cache an additional method to track the resource usage, other than counting cache items. This is useful when the cache items differ in size.

In most cases, using usize as Measure would be good enough.

Required Associated Types

type Measure: Default + Copy + Ord + Display + Add<Output = Self::Measure> + Sub<Output = Self::Measure>

The type used to store measurements.

Required Methods

fn measure<Q: ?Sized>(&self, key: &Q, value: &V) -> Self::Measure

where K: Borrow<Q>,

Calculate the size of key and value.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<K, V> Meter<K, V> for Count

type Measure = usize