pub trait FieldCount {
fn field_count() -> usize;
}
pub use field_count_derive::*;
#[cfg(test)]
mod tests {
use super::FieldCount;
#[test]
fn test_derive_field_count_for_struct() {
assert_eq!(MyStruct::field_count(), 3);
}
#[test]
fn test_derive_field_count_for_generic_struct() {
assert_eq!(MyGenericStruct::<u32>::field_count(), 1);
}
#[test]
fn test_derive_field_count_as_trait() {
assert_eq!(field_count::<MyStruct>(), 3);
}
fn field_count<T: FieldCount>() -> usize {
T::field_count()
}
#[derive(FieldCount)]
struct MyStruct {
_first_field: i32,
_second_field: String,
_third_field: u16,
}
#[derive(FieldCount)]
struct MyGenericStruct<T> {
_generic_field: T,
}
}