How to create a vector of generic functions in Rust

Question

fn render_task_enter_field<W>(stdout: &mut W)
where
    W: Write,
{
    ...
}

I need to add this function to vector. I will iterate it and call each function.

I have tried Vec<fn(&mut impl Write)>, but it does not work

How can I call my function? I want to pass the variable described below to this function.

let mut stdout = stdout()
        .into_raw_mode()
        .expect("Cannot run raw mode")
        .into_alternate_screen()
        .expect("Cannot run alternate screen");

I use termion crate

Answer 1

You want this:

Vec<Box<dyn Fn(&mut dyn Write)>>

A vector of boxes containing a dynamic type of function that takes a dynamic object that implement write.

You can't add generic functions to an array since it's really just a whole bunch of separate function, but you can just make it take a trait object as an argument to get the same effect.

Full example:

use std::io::Write;

fn render_task_enter_field(stdout: &mut dyn Write)
{
}


fn main() {
    let mut k:Vec<Box<dyn Fn(&mut dyn Write)>> = vec![];

    k.push(Box::new(render_task_enter_field));
   
    for m in k {
        m(&mut std::io::stdout());
    }
}