Getting Started DI example naive Rust implementation from https://autofac.readthedocs.io/en/latest/getting-started/index.html

AutoFacGettingStarted.rs

#![feature(existential_type)]
use chrono::Local;
use std::io::{self, Write};
type Result<T> = std::result::Result<T, failure::Error>;

trait IOutput {
    fn write(&self, content: &String) -> Result<()>;
}

struct ConsoleOutput {}

impl ConsoleOutput {
    fn new() -> Self { Self {} }
}

impl IOutput for ConsoleOutput {
    fn write(&self, content: &String) -> Result<()> {
        io::stdout().write(content.as_bytes())?;
        Ok(())
    }
}

trait IDateWriter {
    fn write_date(&self) -> Result<()>;
}

struct TodayWriter<O: IOutput> {
    output: O,
}

impl<O: IOutput> TodayWriter<O> {
    fn new(output: O) -> Self {
        Self { output, }
    }
}

impl<O: IOutput> IDateWriter for TodayWriter<O> {
    fn write_date(&self) -> Result<()> {
        self.output.write(&Local::today()
                                 .format("%b %d, %Y").to_string())
    }
}

trait IContainer {
    type IOutputType: IOutput;
    type IDateWriterType: IDateWriter;
    
    fn resolve_i_output() -> Self::IOutputType;
    fn resolve_i_date_writer() -> Self::IDateWriterType;
}

struct Container {}

impl IContainer for Container {
    existential type IOutputType: IOutput;
    existential type IDateWriterType: IDateWriter;
    
    fn resolve_i_output() -> Self::IOutputType { ConsoleOutput::new() }
    fn resolve_i_date_writer() -> Self::IDateWriterType { 
        TodayWriter::new(Container::resolve_i_output())
    }
}


fn main() -> Result<()> {
    let writer = Container::resolve_i_date_writer();
    writer.write_date()
}