use {MultiDeciderImpl, TypedDecider, ImpliedDeciderImpl, MultiDecider, Decider, Decision, Result};

use std::time::Instant;

impl Decider for Allower {}
impl MultiDecider for Allower {}

#[derive(Default, Copy, Clone)]
/// The most naive implementation of a rate-limiter ever: Always
/// allows every cell through.
/// # Example
/// ```
/// use ratelimit_meter::{Decider};
/// use ratelimit_meter::example_algorithms::Allower;
/// let mut allower = Allower::new();
/// assert!(allower.check().unwrap().is_compliant());
/// ```
pub struct Allower {}

impl Allower {
    pub fn new() -> Allower {
        Allower::default()
    }
}

impl TypedDecider for Allower {
    /// Allower never returns a negative answer, so negative answers
    /// don't carry information.
    type T = ();
}

impl MultiDeciderImpl for Allower {
    /// Allows all cells through unconditionally.
    fn test_n_and_update(&mut self, _n: u32, _t0: Instant) -> Result<Decision<()>> {
        Ok(Decision::Yes)
    }
}

impl ImpliedDeciderImpl for Allower {}

use {MultiDeciderImpl, TypedDecider, ImpliedDeciderImpl, MultiDecider, Decider, Decision, Result};

use std::time::Instant;

impl Decider for Allower {}
impl MultiDecider for Allower {}

#[derive(Copy, Clone)]
/// The most naive implementation of a rate-limiter ever: Always
/// allows every cell through.
/// # Example
/// ```
/// use ratelimit_meter::{Decider};
/// use ratelimit_meter::example_algorithms::Allower;
/// let mut allower = Allower::new();
/// assert!(allower.check().unwrap().is_compliant());
/// ```
pub struct Allower {}

impl Allower {
    pub fn new() -> Allower {
        Allower {}
    }
}

impl TypedDecider for Allower {
    /// Allower never returns a negative answer, so negative answers
    /// don't carry information.
    type T = ();
}

impl MultiDeciderImpl for Allower {
    /// Allows all cells through unconditionally.
    fn test_n_and_update(&mut self, _n: u32, _t0: Instant) -> Result<Decision<()>> {
        Ok(Decision::Yes)
    }
}

impl ImpliedDeciderImpl for Allower {}

--- 
+++ 
@@ -5,7 +5,7 @@
 impl Decider for Allower {}
 impl MultiDecider for Allower {}
 
-#[derive(Copy, Clone)]
+#[derive(Default, Copy, Clone)]
 /// The most naive implementation of a rate-limiter ever: Always
 /// allows every cell through.
 /// # Example
@@ -19,7 +19,7 @@
 
 impl Allower {
     pub fn new() -> Allower {
-        Allower {}
+        Allower::default()
     }
 }
 
Make clippy happy: Derive Default for Allower
