Trait HasField

Source

pub trait HasField<Tag> {
    type Value;

    // Required method
    fn get_field(&self, _tag: PhantomData<Tag>) -> &Self::Value;
}

Expand description

The HasField trait is used to implement getter methods for a type that derives the trait.

When a struct uses #[derive(HasField)], the macro would generate a HasField implementation for each field in the struct, with the field name becoming a type-level string to be used in the generic Tag parameter.

§Example

Given the following struct:

#[derive(HasField)]
pub struct Person {
    pub name: String,
    pub age: u8,
}

The macro would generate the following implementation:

impl HasField<Symbol!("name")> for Person {
    type Value = String;

    fn get_field(&self, _tag: PhantomData<Symbol!("name")>) -> &Self::Value {
        &self.name
    }
}

impl HasField<Symbol!("age")> for Person {
    type Value = u8;

    fn get_field(&self, _tag: PhantomData<Symbol!("age")>) -> &Self::Value {
        &self.age
    }
}