rust - 如何从 `self`设置关联常量(在rust中)

Question

如果我的特征定义为:

pub trait foo {
  const ID: u32;
  ...

和一个结构定义为:

pub struct fooStruct {
  pub id: u32,
  pub name: vec<u8>,
  ...
}

当我实现 fooStruct的特征时，我想做类似的事情:

impl foo for footStruct {
  const ID: u32 = self.id // self does not work here
}

我的问题是:如何通过读取实现ID的结构来设置ID const(如果可能的话)？
谢谢

Answer 1

How can i set my ID const by reading from the struct that is implementing it (if its possible at all)?

我认为这是不可能的。

Like immutable variables, constants are values that are bound to a name and are not allowed to change, but there are a few differences between constants and variables...

...constants may be set only to a constant expression, not the result of a function call or any other value that could only be computed at runtime.

self.id是在运行时计算的值， const ID: u32 = self.id 将不起作用。
此外， self仅存在于方法中。