pub trait Decode<'b, C>: Sized {
// Required method
fn decode(d: &mut Decoder<'b>, ctx: &mut C) -> Result<Self, Error>;
// Provided method
fn nil() -> Option<Self> { ... }
}Expand description
A type that can be decoded from CBOR.
Required Methods§
Sourcefn decode(d: &mut Decoder<'b>, ctx: &mut C) -> Result<Self, Error>
fn decode(d: &mut Decoder<'b>, ctx: &mut C) -> Result<Self, Error>
Decode a value using the given Decoder.
In addition to the decoder a user provided decoding context is given
as another parameter. Most implementations of this trait do not need
a decoding context and should be completely generic in the context
type. In cases where a context is needed and the Decode impl type is
meant to be combined with other types that require a different context
type, it is preferrable to constrain the context type variable C with
a trait bound instead of fixing the type.
Provided Methods§
Sourcefn nil() -> Option<Self>
fn nil() -> Option<Self>
If possible, return a nil value of Self.
This method is primarily used by minicbor-derive and allows
creating a special value denoting the absence of a “real” value if
no CBOR value is present. The canonical example of a type where
this is sensible is the Option type, whose Decode::nil method
would return Some(None).
With the exception of Option<_> all types T are considered
mandatory by default, i.e. T::nil() returns None. Missing values
of T therefore cause decoding errors in derived Decode
implementations.
NB: A type implementing Decode with an overriden Decode::nil
method should also override Encode::is_nil if it implements Encode
at all.
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.