derive-from-one

Autogeneration of From impls for enums and structs.

Installation

Add to Cargo.toml:

toml derive-from-one = "0.1"

Usage

This macro generates From impls for enum constructors with a single field.

If you don't want some impls to be generated, apply #[from(skip)] to this tag.

Also, the macro would automatically skip ambiguous types, i.e., when a type appears in multiple tags regardless of amount of fields.

Example:

```rust use derivefromone::FromOne;

[derive(FromOne)]

enum Enum { A { a: u32 }, // GENERATES From impl B(bool), // GENERATES From impl #[from(skip)] C(String), // DOES NOT GENERATE From impl due to #[from(skip)] attribute D { // DOES NOT GENERATE From impl due to multiple fields foo: Vec, bar: &'static str, }, E(Vec) // DOES NOT GENERATE From impl due to Vec appears in D tag } ```

Generated code:

```rust enum Enum { A { a: u32 }, B(bool), C(String), D { foo: Vec, bar: &'static str, }, E(Vec) }

impl From for Enum { fn from(x: u32) -> Self { Self::A { a: x } } }

impl From for Enum { fn from(x: bool) -> Self { Self::B(x) } } ```

You can also apply this macro to structs with a single field.

```rust use derivefromone::FromOne;

[derive(FromOne)]

struct StructOne(usize);

[derive(FromOne)]

struct StructTwo { a: usize } ```

License

MIT.