Macro impl_field_descriptors 

macro_rules! impl_field_descriptors {
    ($struct_name:ident { $( $field_name:ident : $field_type:ty ),* $(,)? }) => { ... };
}

Macro to implement field descriptors for struct fields

This macro generates FieldDescriptor implementations and static methods for each field, allowing direct struct field access without the need for separate accessor types.

Example

struct TradingMetrics {
    total_volume: u64,
    trade_count: u64,
}

impl_field_descriptors!(TradingMetrics {
    total_volume: u64,
    trade_count: u64
});

// Now you can use:
ctx.get_field(TradingMetrics::total_volume())
ctx.set_field(TradingMetrics::total_volume(), 1000)