Returned from Serializer::serialize_seq.

Example use

# use std::marker::PhantomData;
#
# struct Vec<T>(PhantomData<T>);
#
# impl<T> Vec<T> {
#     fn len(&self) -> usize {
#         unimplemented!()
#     }
# }
#
# impl<'a, T> IntoIterator for &'a Vec<T> {
#     type Item = &'a T;
#     type IntoIter = Box<dyn Iterator<Item = &'a T>>;
#     fn into_iter(self) -> Self::IntoIter {
#         unimplemented!()
#     }
# }
#
use serde::ser::{Serialize, SerializeSeq, Serializer};

impl<T> Serialize for Vec<T>
where
    T: Serialize,
{
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        let mut seq = serializer.serialize_seq(Some(self.len()))?;
        for element in self {
            seq.serialize_element(element)?;
        }
        seq.end()
    }
}

Example implementation

The example data format presented on the website demonstrates an implementation of SerializeSeq for a basic JSON data format.