🎁 [Feature Request]: feature to derive Debug on generated types

[jkneer]

What is the feature you would like to see?

When integrating a builder for a subaspect into another implementation for a larger struct, you may run into the situation where you have to explicitely return or take a stated type generated by state-shift. It would be nice to have Debug derives as a crate feature flag in those cases...

[ozgunozerk]

Instead of that, we can have a simpler solution.

The macro for the struct #[type_state] is able to capture other macro annotations on top of the struct, so it can preserve them and place the other macros on top of the generated struct (type-state version of the struct).

I think this would be a more generalized approach. What do you think @jkneer ?

[jkneer]

Hi,

yes that would be good, as currently the behaviour depends on the order of the annotations

# derive Debug
# type state 

-> Debug is derived on the struct
edit just tested that, rust-analyzer says it is, but in reality it is not for the stated versions of the struct that is annotated.

# type state
# derive Debug

-> Debug is not derived.

Hmm I guess that would be mostly ok, for Debug, Clone, Copy

What if the trait cannot be derived? like Send or Sync?

[ozgunozerk]

What if the trait cannot be derived? like Send or Sync?

The macro does not change the struct name, one can always implement the traits manually.

[jkneer]

The macro does not change the struct name, one can always implement the traits manually.

Wouldn't all State types also need carry those traits?

[ozgunozerk]

Wouldn't all State types also need carry those traits?

Yes. As long as the generic type T implements Trait, it should be ok and we should not need any manual implementation for the variants of T. For example:

#[derive(Debug)]
struct MyStruct<T = bool> {
    value: T,
}

fn main() {
    let int_struct = MyStruct { value: 42 };
    let string_struct = MyStruct { value: String::from("Hello") };

    println!("{:?}", int_struct); // Works because i32 implements Debug
    println!("{:?}", string_struct); // Works because String implements Debug
}