How do I disambiguate traits in Rust?

Question

I want to use the write_fmt method on two different types of object:

use std::fmt::Write;
use std::io::Write;

fn main() {
    let mut a = Strin         


        

Answer 1

You can call the trait method directly:

fn main() {
    let mut a = String::new();
    let mut b = std::fs::File::create("test").unwrap();

    std::fmt::Write::write_fmt(&mut a, format_args!("hello"));
    std::io::Write::write_fmt(&mut b, format_args!("hello"));
}

You can also choose to only import the trait in a smaller scope:

fn main() {
    let mut a = String::new();
    let mut b = std::fs::File::create("test").unwrap();

    {
        use std::fmt::Write;
        a.write_fmt(format_args!("hello"));
    }

    {
        use std::io::Write;
        b.write_fmt(format_args!("hello"));
    }
}

---

Note that if you choose to use a smaller scope, you can also use the write! macro directly:

fn main() {
    let mut a = String::new();
    let mut b = std::fs::File::create("test").unwrap();

    {
        use std::fmt::Write;
        write!(a, "hello");
    }

    {
        use std::io::Write;
        write!(b, "hello");
    }
}

In either case, you should handle the Result return value.

See also:

• How to call a method when a trait and struct use the same name?