Generics

Build works with generic structs. Type parameters and where-clause bounds are forwarded to the generated builder type unchanged.

Basic Generic Struct

use moxy::Build;

#[derive(Build, Default)]
struct Wrapper<T: Default> {
    #[moxy(build)]
    pub value: T,
}

let w: Wrapper<u32> = Wrapper::new().value(42u32).build();
assert_eq!(w.value, 42u32);

The generated builder is WrapperBuilder<T, const VALUE: bool> — type parameters are forwarded and const bool parameters track required fields. Wrapper::new() returns a WrapperBuilder<T> with all const generics defaulted to false. All generics are inferred from the call site.

With Defaults

Generic fields can have defaults too, as long as the default expression is compatible with the type parameter’s bounds:

use moxy::Build;

#[derive(Build, Default)]
struct Container<T: Default + Clone> {
    #[moxy(build)]
    pub value: T,
    pub label: String,   // not in builder — receives Default::default()
}

let c: Container<i32> = Container::new().value(99).build();
assert_eq!(c.value, 99);
assert_eq!(c.label, "");