This crate requires a nightly (unstable, experimental) compiler version. To switch to it, you must have Rust installed via Rustup, and run:

rustup default nightly

Run rustup default stable to switch back.

Adding `derive_from` library as a dependency

Run this command in a terminal, in your project's directory:

cargo add derive_from

To add it manually, edit your project's Cargo.toml file and add to the [dependencies] section:

derive_from = "0.1.1"

The derive_from library will be automatically available globally.

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Readme

derive_from

Rust derive(From) macro

It only works for tuple structs with one element (newtypes) or enums containing these tuple structs. The types wrapped by these tuple structs can than simply be converted by using the .into() method.

For enums no from code will be generated for types that occur multiple times since this would be ambiguous.

It can simply be used like this:

#[derive(From)]
struct MyInt(i32);

#[derive(From)]
enum MyIntEnum{
    Int(i32),
    Bool(bool),
    UnsignedOne(u32),
    UnsignedTwo(u32),
    Nothing,
}

The resulting code that will be compiled will look like this:

struct MyInt(i32);
impl ::std::convert::From<i32> for MyInt {
    fn from(a: i32) -> MyInt { MyInt(a) }
}


enum MyIntEnum {
    Int(i32),
    Bool(bool),
    UnsignedOne(u32),
    UnsignedTwo(u32),
    Nothing,
}
impl ::std::convert::From<i32> for MyIntEnum {
    fn from(a: i32) -> MyIntEnum { MyIntEnum::Int(a) }
}
impl ::std::convert::From<bool> for MyIntEnum {
    fn from(a: bool) -> MyIntEnum { MyIntEnum::Bool(a) }
}

Because of this and Rust its built in type inference the following can be done now:

fn main() {
    let my_enum_val = MyIntEnum::Int(5);

    if en_enum_val == 5.into() {
        println!("The content of my_enum_val is 5")
    }
}

Adding derive_from library as a dependency

Adding `derive_from` library as a dependency