Rust : 关于*const () 与type erase

*const () 可以替代泛型，更加灵活。

一、 代码

struct Foo(String);impl Work for Foo {fn process(&self) {println!("process work  from Foo :  {}", self.0);}
}
struct Bar(String);
impl Work for Bar {fn process(&self) {println!("process work  from Bar : {}", self.0);}
}
fn fn_foo(foo: &Foo){println!("call fn_foo, output ->{}", foo.0);
}
fn fn_bar(bar: &Bar){println!("call fn_bar, output ->{}", bar.0);
}
fn main() {let foo = Foo("foo".into());let bar = Bar("bar".into());let unsafe_fn_foo: unsafe fn(*const ()) = unsafe {std::mem::transmute(fn_foo as fn(&Foo))};process_method::<Foo>( unsafe_fn_foo,&foo,);let unsafe_fn_bar: unsafe fn(*const ()) = unsafe {std::mem::transmute(fn_bar as fn(&Bar))};process_method::<Bar>(unsafe_fn_bar,&bar,);let foo_ptr: *const () = &foo as *const Foo as _;let bar_ptr: *const () = &bar as *const Bar as _;process_data::<Foo>(foo_ptr);process_data::<Bar>(bar_ptr);
}
trait Work {fn process(&self);
}
// 泛型化数据
fn process_data<T: Work>(data: *const ()) {let obj: *const T = data.cast::<T>();unsafe{(*obj).process()};
}
// 泛型化函数
fn process_method<T>(f:  unsafe fn(*const ()),data:&T) {let ptr: *const () = data as *const T as _;unsafe{f(ptr)};
}

二、输出结果

PS D:\my_program\type_erase> cargo run --releaseFinished `release` profile [optimized] target(s) in 0.02sRunning `target\release\type_erase.exe`
call fn_foo, output ->foo    
call fn_bar, output ->bar    
process work  from Foo :  foo
process work  from Bar : bar