strong-type

strong-type is a Rust crate that offers macros to easily create strongly typed and named primitive and string types. Strong typing helps in making code more expressive and less prone to errors, ensuring that each type is used in its intended way.

use strong_type::StrongType;

#[derive(StrongType)]
struct Timestamp(i64);

let timestamp = Timestamp::new(1701620628123456789);
println!("{}", timestamp); // Timestamp(1701620628123456789)

Features

• StrongType: Create a named strong type. The macro automatically implement common traits like Clone, Debug, Default, PartialEq, PartialOrd, Send, Sync, and Display (unless the custom_display attribute is used to override it). Additionally, depending on the underlying data type, strong-typed structs may also implement Copy, Eq, Ord, Hash. For example, if the underlying type is a primitive data type like i32 or bool, these additional traits will be implemented. This allows the strong types to inherit useful behaviors from their underlying types, while still maintaining their distinct identity at the type level.
• StrongNumericType: Extend StrongType with arithmetic/logical operations.
• custom_display: Provides flexibility for users to manually implement Display instead of using the default display format.

Installation

Add strong-type to your Cargo.toml:

[dependencies]
strong-type = "*" # Using the latest version or specify a version number

Supported underlying types:

• Both StrongType and StrongNumericType:
  • Integer types: i8, i16, i32, i64, i128, isize
  • Unsigned integer types: u8, u16, u32, u64, u128, usize
  • Floating-point types: f32, f64
  • Boolean type: bool
• Only StrongType:
  • char
  • String

Examples

Creating a named strong type:

use strong_type::StrongType;

#[derive(StrongType)]
struct Tag(String);

let tag = Tag::new("dev");
let tag: Tag = "dev".into(); // Alternative instantiation

Demonstrating type distinctiveness:

use strong_type::StrongType;
use std::any::Any;

#[derive(StrongType)]
struct Second(i32);

#[derive(StrongType)]
struct Minute(i32);

let x = Second::new(2);
let y = Second::new(3);
let z = Minute::new(3);

assert_eq!(x.type_id(), y.type_id()); // Same type: Second
assert_ne!(y.type_id(), z.type_id()); // Different types: Second versus Minute

Utilizing Hashability:

use std::collections::HashSet;

#[derive(StrongType)]
struct Tag(String);

let mut map = HashSet::<Tag>::new();
map.insert(Tag::new("dev"));
map.insert(Tag::new("prod"));
assert_eq!(map.len(), 2);

Named integer type with arithmetic operations:

use strong_type::StrongNumericType;

#[derive(StrongNumericType)]
struct Second(i32);

let x = Second::new(2);
let y = Second::new(3);
let z = Second::default();

assert_eq!(x.value(), 2);
assert_eq!(y.value(), 3);
assert_eq!(z.value(), 0);
assert!(x < y);
assert!(y >= x);
assert_eq!(x + y, Second(5));

Named bool type with logical operations:

use strong_type::StrongNumericType;

#[derive(StrongNumericType)]
struct IsTrue(bool);

let x = IsTrue::new(true);
let y = IsTrue::new(false);

assert_eq!(x & y, IsTrue::new(false));
assert_eq!(x | y, IsTrue::new(true));
assert_eq!(x ^ y, IsTrue::new(true));
assert_eq!(!x, IsTrue::new(false));

Custom display implementation with custom_display:

use std::fmt::{Display, Formatter, Result};
use strong_type::StrongNumericType;

#[derive(StrongNumericType)]
#[custom_display]
struct Second(f64);

impl Display for Second {
   fn fmt(&self, f: &mut Formatter) -> Result {
      write!(f, "Second({:.2})", &self.0)
   }
}

println!("{}", Second::new(std::f64::consts::E)); // "Second(2.72)"
println!("{:?}", Second::new(std::f64::consts::E)); // "Second { value: 2.718281828459045 }"