从另一个静态方法(rust)调用特征静态方法 [英] Calling trait static method from another static method (rust)

问题描述

你能从另一个在 trait 中实现的 trait 静态方法调用一个由类型实现的 trait 静态方法吗?例如:

Can you call a trait static method implemented by types from another trait static method implemented in the trait? For example:

trait SqlTable {
  fn table_name() -> String;

  fn load(id: i32) -> Something {
    ...
    Self::table_name()    // <-- this is not right
    ...
  }
}

感谢 Chris 和 Arjan(请参阅下面的评论/答案)

This is now working thanks to Chris and Arjan (see comments/answers below)

fn main() {
  let kiwibank = SqlTable::get_description(15,None::<Account>);
}

trait SqlTable {
    fn table_name(_: Option<Self>) -> String;

    fn get_description(id: i32, _: Option<Self>) -> String {
        println!("Fetching from {} table", SqlTable::table_name(None::<Self>) );
        String::from_str("dummy result")
    }
}

struct Account {
    id: i32,
    name: String,
}
impl SqlTable for Account {
    fn table_name(_: Option<Account>) -> String { String::from_str("account") }
}

推荐答案

• 是的，您可以从另一个特征静态方法[在特征中实现] 调用特征静态方法[由类型实现].
• 静态方法总是在像 SomeTrait::some_method() 这样的特征上被调用.
• [a trait] 函数签名中没有 Self 或 self 的地方，目前是不可调用的.UFCS 出现之前的标准解决方法是采用参数 _: Option 并将其传递给 None::.
• Yes, you can call a trait static method [implemented by types] from another trait static method [implemented in the trait].
• Static methods are always called on a trait like SomeTrait::some_method().
• Where there is no Self or self in [a trait] function signature, it is not callable at present. The standard workaround until UFCS comes is to take an argument _: Option<Self> and pass it None::<T>.

有关(截至今天)编译的代码的原始问题.

See original question for code that (as of today) compiles.

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