ace_it

Auto Convert Enums

Description

Just a small proc_macro to automatically generate From trait impls for each unnamed variant of an enum

Usage

Cargo.toml:

[dependencies]
ace_it = "0.1"

Example

#[macro_use]
extern crate ace_it;

#[derive(Debug)]
#[ace_it]
enum Error {
  Io(std::io::Error),
  ParseInt(std::num::ParseIntError),
  ParseFloat(std::num::ParseFloatError),
}

use std::io::Read;

fn read_int<R: Read>(reader: &mut R) -> Result<i32, Error> {
    let mut buf = String::new();
    reader.read_to_string(&mut buf)?;
    Ok(buf.parse()?)
}

Future features

• Attribute for ignoring a variant

lib.rs:

Auto Convert Enums

This crate provides a proc macro that generates [From] impls for unnamed enum fields that have a type.

Ever get tired of writing the same From impls to enable using ? on some [Result] types? This crate is for you!

This is useful for enums that are used as a wrapper for a collecting multiple errors into one big enum.

Example

#[macro_use] extern crate ace_it;

#[derive(Debug)]
#[ace_it]
enum Error {
  Io(std::io::Error),
  ParseInt(std::num::ParseIntError),
  ParseFloat(std::num::ParseFloatError),
}

After this, Error has three [From] impls:

• [From]<std::io::Error> for Error
• [From]<std::num::ParseIntError> for Error
• [From]<std::num::ParseFloatError> for Error

Now you can use ? on any of these types and get an Error back.

use std::io::Read;

fn read_int<R: Read>(reader: &mut R) -> Result<i32, Error> {
    let mut buf = String::new();
    reader.read_to_string(&mut buf)?;
    Ok(buf.parse()?)
}