Derive Macro druid_derive::Data

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    // Attributes available to this derive:
Expand description

Generates implementations of the Data trait.

This macro supports a data field attribute with the following arguments:

  • #[data(ignore)] makes the generated Data::same function skip comparing this field.
  • #[data(same_fn="foo")] uses the function foo for comparing this field. foo should be the name of a function with signature fn(&T, &T) -> bool, where T is the type of the field.
  • #[data(eq)] is shorthand for #[data(same_fn = "PartialEq::eq")]


use druid_derive::Data;

#[derive(Clone, Data)]
struct State {
    number: f64,
    // `Vec` doesn't implement `Data`, so we need to either ignore it or supply a `same_fn`.
    // same as #[data(same_fn="PartialEq::eq")]
    indices: Vec<usize>,
    // This is just some sort of cache; it isn't important for sameness comparison.
    cached_indices: Vec<usize>,