我正在尝试创建一个通用结构来包装isize
or an AtomicIsize
,但是当我尝试为该结构的两种可能实现实现一个特征时,我遇到了错误。我创建了一个最小的示例来演示我的问题如下。
use std::sync::atomic::{AtomicIsize, Ordering};
use std::ops::Deref;
use std::marker::PhantomData;
pub trait Counted {
fn inc(&self, value: isize);
}
pub type PlainCounter = isize;
pub type AtomicCounter = AtomicIsize;
pub struct Counter<'a, T: 'a> {
counter: T,
phantom: PhantomData<&'a T>,
}
impl<'a, T> Counter<'a, T>
where T: Deref<Target = PlainCounter>
{
pub fn new(counter: T) -> Self {
Counter {
counter: counter,
phantom: PhantomData,
}
}
}
impl<'a, T> Counted for Counter<'a, T>
where T: Deref<Target = PlainCounter>
{
fn inc(&self, value: isize) {
self.counter += 1;
}
}
impl<'a, T> Counter<'a, T>
where T: Deref<Target = AtomicCounter>
{
pub fn new(counter: T) -> Self {
Counter {
counter: counter,
phantom: PhantomData,
}
}
}
impl<'a, T> Counted for Counter<'a, T>
where T: Deref<Target = AtomicCounter>
{
fn inc(&self, value: isize) {
self.counter.fetch_add(value, Ordering::SeqCst);
}
}
()
我得到的错误是编译器发现conflicting implementations of trait `Counted` for type `Counter<'_, _>`
。编译器似乎无法确定实现是针对两种不同类型的T
,即T: Deref<Target = PlainCounter>
and T: Deref<Target = AtomicCounter>
。也许有一种方法可以向编译器提供附加信息,以便它可以区分这两种情况,或者我完全走错了路?