Macro druid::lens

macro_rules! lens {
    ($ty : ty, [$index : expr]) => { ... };
    ($ty : ty, $($field : tt) *) => { ... };
}

Construct a lens accessing a type’s field

This is a convenience macro for constructing Field lenses for fields or indexable elements.

struct Foo { x: Bar }
struct Bar { y: [i32; 10] }
let lens = druid::lens!(Foo, x);
let lens = druid::lens!((u32, bool), 1);
let lens = druid::lens!([u8], [4]);
let lens = druid::lens!(Foo, x.y[5]);