Derive macros for the from_as crate

This crate is meant to be used as part of the from_as crate and may work as intended by itself.

Please use https://crates.io/crates/from_as

from_as

Rust derive macros for reading and writing files for types that implement serde. The derive macros implement the fromasfile traits.

The fromasfile crate provides two traits: FromFile and AsFile. FromFile is used for getting types from a file. AsFile is used for writing a types to a file.

The derivefromas crate provides derive macros for these traits with the same names.

Currently, the only files types that can be used are json, yaml, and toml.

Example

```rust #[macrouse] extern crate serdederive; use std::io::{Read, Write}; use std::convert::TryFrom; use from_as::*;

#[derive(Debug, Deserialize, Serialize, AsFile, FromFile)]
struct Attribute {
    name: String,
}

fn main() {
    let attr = Attribute { 
        name: "attr_name".into()
    };

    // Write to the example directory.
    attr.as_file("./examples/attr.json").unwrap();

    let attr = Attribute::from_file("./examples/attr.json").unwrap();
    println!("{:#?}", attr);

    // For writing a prettified version.
    attr.as_file_pretty("./examples/attr.json").uwnrap();
}

```