1 unstable release
0.1.0 | Mar 16, 2024 |
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#1026 in Procedural macros
34 downloads per month
5KB
76 lines
Yet Another Rust Builder Pattern Derive Macro
Usage
#[derive(Builder)]
struct Foo {
pub a: i32,
pub b: String,
pub c: bool,
pub d: Option<usize>,
}
let foo = Foo::builder()
.a(-3)
.b("Hello, world!".to_string())
.c(true)
.d(Some(2048))
.build();
assert_eq!(-3, foo.a);
assert_eq!("Hello, world!".to_string(), foo.b);
assert_eq!(true, foo.c);
assert_eq!(Some(2048), foo.d);
Note
The macro requires that fields implement the Default
. When a value for the field is not provided it will assign the default value:
#[derive(Builder)]
struct DefaultFoo {
pub a: i32,
pub b: bool,
}
let foo = DefaultFoo::builder()
.build();
assert_eq!(0, foo.a);
assert_eq!(false, foo.b);
Declaring fields that do not implement the Default
trait will result in a compile error:
pub struct NonDefault {}
#[derive(Builder)]
pub struct Foo {
d: NonDefault, // error[E0277]: the trait bound `NonDefault: Default` is not satisfied
}
Dependencies
~260–710KB
~17K SLoC