Mark fields of property non-optional with attribute

[bytesnake]

The following pattern is used to pass states between elements:

#[derive(Props)]
struct ResultsProps {
    current_idx: Option<State<isize>>,
}

#[component]
fn Results(props: &ResultsProps, mut hooks: Hooks) -> impl Into<AnyElement<'static>> {
    let Some(mut current_idx) = props.current_idx else {
        panic!("index is required");
    };

   ...
}

I propose to add an attribute #[iocraft(required)] to mark fields as non-optional when constructing elements

#[derive(Props)]
struct ResultsProps {
    #[iocraft(required)]
    current_idx: State<isize>,
}

#[component]
fn Results(props: &ResultsProps, mut hooks: Hooks) -> impl Into<AnyElement<'static>> {
   ...
}

[ccbrown]

I like the suggestion. The only thing that's unclear to me is what happens when a required field's type doesn't implement Default.

I think to handle that reasonably, we would have to drop the Default implementation on the props like...

#[derive(Props)]
struct ResultsProps {
    optional_thing: Option<OptionalThing>,

    #[iocraft(required)]
    required_thing: RequiredThing
}

Or...

#[derive(Props)]
struct ResultsProps {
    #[iocraft(default)]
    optional_thing: Option<OptionalThing>,

    required_thing: RequiredThing
}

The latter would be more familiar to users of Serde. In fact, we could also extend it to allow for some of Serde's additional features like:

#[derive(Props)]
struct ResultsProps {
    #[iocraft(default = "OptionalThing::foo")]
    optional_thing: OptionalThing,

    required_thing: RequiredThing
}

The downside though is that assuming the majority of fields are optional, you'd have to add attributes to the majority of your fields. So maybe a hybrid approach is best:

#[derive(Props)]
struct ResultsProps {
    // Explicitly specify the default value.
    #[iocraft(default = "OptionalThing::foo")]
    optional_thing: OptionalThing,

    // Default behavior is to use `Default`. Most fields should look like this.
    other_optional_thing: Option<OptionalThing>,

    // Must be provided by user.
    #[iocraft(required)]
    required_thing: RequiredThing
}

[bytesnake]

mh that seems quite boilerplaty, maybe drop the requirements for Default trait on the whole struct and require only that individual fields have to implement default, except for required fields. Then update the assignment to call Default::default for all non-required fields here: https://github.com/ccbrown/iocraft/blob/main/packages/iocraft-macros/src/lib.rs#L124-L125 and fill out the missing (required) from macro invocation

[ccbrown]

mh that seems quite boilerplaty, maybe drop the requirements for Default trait on the whole struct and require only that individual fields have to implement default, except for required fields. Then update the assignment to call Default::default for all non-required fields here: https://github.com/ccbrown/iocraft/blob/main/packages/iocraft-macros/src/lib.rs#L124-L125 and fill out the missing (required) from macro invocation

Yeah I think that's basically my last example, which I edited in right after posting. 👍