[英]how to avoid unconstrained type paramameter error
如果不使用不受約束的類型,我想不出一種方法來獲得以下功能。
struct Things<T> {
thing: T
}
trait ThingActions<D> {//will be implemented for 'D's of different types
fn foo(&self, data: D) {}
fn bar(&self, data: D) {}
}
impl<T: ThingActions<D>, D> Things<T> {
fn do_foos(&self, data: D) {//any D with corresponding foo can be used here
self.thing.foo(data)
}
}
impl<T: ThingActions<D>, D: Send + Sync> Things<T> {
fn do_bars_multithreaded(&self, data: D) {
self.thing.bar(&self.thing, data)//this happens in a different thread
}
}
我的最終目標是讓下面的代碼適用於 foo 和 bar 的任何配置,而對它的更改相對較少。
fn main(){
let number = Things {thing: 5isize};
number.do_foos(2);
number.do_foos('a');
}
impl ThingActions<isize> for isize {
fn foo(&self, data: isize){
println!("{}", data + self)
}
}
impl ThingActions<char> for isize {
fn foo(&self, data: char){
println!("{}, {}", data, self)
}
}
也有可能的情況是除了“事物”之外什么都不使用。
您可以嘗試僅在fn
上綁定D
,而不是在整個結構上:
struct Things<T> {
thing: T
}
trait ThingActions<D> {//will be implemented for 'D's of different types
fn foo(&self, data: D) {}
fn bar(&self, data: D) {}
}
impl<T> Things<T> {
fn do_foos<D>(&self, data: D)
where T: ThingActions<D>
{//any D with corresponding foo can be used here
self.thing.foo(data)
}
}
impl<T> Things<T> {
fn do_bars_multithreaded<D>(&self, data: D)
where T: ThingActions<D>, D: Send + Sync
{
self.thing.bar(data)//this happens in a different thread
}
}
fn main(){
let number = Things {thing: 5isize};
number.do_foos(2);
number.do_foos('a');
}
impl ThingActions<isize> for isize {
fn foo(&self, data: isize){
println!("{}", data + self)
}
}
impl ThingActions<char> for isize {
fn foo(&self, data: char){
println!("{}, {}", data, self)
}
}
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