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36 lines
1.3 KiB
Markdown
36 lines
1.3 KiB
Markdown
# TryFromInt - A convenient derive macro for converting an integer to an enum
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## Quick Start
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To use this crate, first add this crate to your `Cargo.toml`.
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```toml
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[dependencies]
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int-to-c-enum = "0.1.0"
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```
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You can use this macro for a [C-like enum](https://doc.rust-lang.org/stable/rust-by-example/custom_types/enum/c_like.html).
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```rust
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use int_to_c_enum::TryFromInt;
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#[repr(u8)]
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#[derive(TryFromInt, Debug)]
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pub enum Color {
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Red = 1,
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Blue = 2,
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Green = 3,
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}
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```
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Then, you can use `try_from` function for this enum.
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```rust
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fn main() {
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let color = Color::try_from(1).unwrap();
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println!("color = {color:?}"); // color = Red;
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}
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```
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## Introduction
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This crate provides a derive procedural macro named `TryFromInt`. This macro will automatically implement [TryFrom](https://doc.rust-lang.org/core/convert/trait.TryFrom.html) trait for enums that meet the following requirements:
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1. The enum must have a primitive repr, i.e., the enum should have attribute like #[repr(u8)], #[repr(u32)], etc. The type parameter of TryFrom will be the repr, e.g., in the `QuickStart` example, the macro will implement `TryFrom<u8>` for `Color`.
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2. The enum must consist solely of unit variants, which is called [units only enum](https://doc.rust-lang.org/reference/items/enumerations.html#unit-only-enum). Each field should have an **explicit discriminant**.
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