Crate derive_getters

source ·
Expand description

This library provides two derive macros. One, Getters for autogenerating getters and Dissolve for consuming a struct returning a tuple of all fields. They can only be used on named structs.

Derives

Only named structs can derive Getters or Dissolve.

Getter methods generated

The getter methods generated shall bear the same name as the struct fields and be publicly visible. The methods return an immutable reference to the struct field of the same name. If there is already a method defined with that name there’ll be a collision. In these cases one of two attributes can be set to either skip or rename the getter.

Getters Usage

In lib.rs or main.rs;

ⓘ
use derive_getters::Getters;

#[derive(Getters)]
struct Number {
    num: u64,    
}

fn main() {
    let number = Number { num: 655 };
    assert!(number.num() == &655);
}

Here, a method called num() has been created for the Number struct which gives a reference to the num field.

This macro can also derive on structs that have simple generic types. For example;

ⓘ
#[derive(Getters)]
struct Generic<T, U> {
    gen_t: T,
    gen_u: U,
}

The macro can also handle generic types with trait bounds. For example;

ⓘ
#[derive(Getters)]
struct Generic<T: Clone, U: Copy> {
    gen_t: T,
    gen_u: U,
}

The trait bounds can also be declared in a where clause.

Additionaly, simple lifetimes are OK too;

ⓘ
#[derive(Getters)]
struct Annotated<'a, 'b, T> {
    stuff: &'a T,
    comp: &'b str,
    num: u64,
}

Getter Attributes

Getters can be further configured to either skip or rename a getter.

  • #[getter(skip)] Will skip generating a getter for the field being decorated.

  • #[getter(rename = “name”)] Changes the name of the getter (default is the field name) to “name”.

ⓘ
 #[derive(Getters)]
 struct Attributed {
     keep_me: u64,

     #[getter(skip)]
     skip_me: u64,

     #[getter(rename = "number")]
     rename_me: u64,
 }

Dissolve method generated

Deriving Dissolve on a named struct will generate a method dissolve(self) which shall return a tuple of all struct fields in the order they were defined. Calling this method consumes the struct. The name of this method can be changed with an attribute.

Dissolve usage

ⓘ
#[derive(Dissolve)]
struct Stuff {
    name: String,
    price: f64,
    count: usize,
}

fn main() {
    let stuff = Stuff {
        name: "Hogie".to_owned(),
        price: 123.4f64,
        count: 100,
    };

    let (n, p, c) = stuff.dissolve();
    assert!(n == "Hogie");
    assert!(p == 123.4f64);
    assert!(c == 100);
}

Dissolve Attributes

You can rename the dissolve function by using a struct attribute.

  • #[dissolve(rename = “name”)]
ⓘ
#[derive(Dissolve)]
#[dissolve(rename = "shatter")]
struct Numbers {
    a: u64,
    b: i64,
    c: f64,
}

Panics

If Getters or Dissolve are derived on unit or unnamed structs, enums or unions.

Cannot Do

Const generics aren’t handled by this macro nor are they tested.

Derive Macros

  • Dissolve
    Produce a dissolve method that consumes the named struct returning a tuple of all the the struct fields.
  • Getters
    Generate getter methods for all named struct fields in a seperate struct impl block. Getter methods share the name of the field they’re ‘getting’. Methods return an immutable reference to the field.