Struct Impossible

Helper type for implementing a Serializer that does not support serializing one of the compound types.

This type cannot be instantiated, but implements every one of the traits corresponding to the Serializer compound types: SerializeSeq, SerializeTuple, SerializeTupleStruct, SerializeTupleVariant, SerializeMap, SerializeStruct, and SerializeStructVariant.

# use serde::ser::{Serializer, Impossible};
# use serde_core::__private::doc::Error;
#
# struct MySerializer;
#
impl Serializer for MySerializer {
    type Ok = ();
    type Error = Error;

    type SerializeSeq = Impossible<(), Error>;
    /* other associated types */

    /// This data format does not support serializing sequences.
    fn serialize_seq(self,
                     len: Option<usize>)
                     -> Result<Self::SerializeSeq, Error> {
        // Given Impossible cannot be instantiated, the only
        // thing we can do here is to return an error.
#         stringify! {
        Err(...)
#         };
#         unimplemented!()
    }

    /* other Serializer methods */
#     serde_core::__serialize_unimplemented! {
#         bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str bytes none some
#         unit unit_struct unit_variant newtype_struct newtype_variant
#         tuple tuple_struct tuple_variant map struct struct_variant
#     }
}