Enum SumDynType

pub enum SumDynType<Type = (), S = ConstU32<0>>
where
    Type: Delimited,
    S: Get<u32> + Clone + Debug + 'static,
{
    None,
    Some(Type),
    Many(BoundedVec<Type, S>),
}

A concrete representation of field cardinality: zero, one, or many values.

SumDynType unifies the possible shapes of a field into a single type:

• absence (None)
• a single value (Some)
• multiple values (Many)

Context

In the virtual field system:

• VirtualDynField defines field behavior abstractly (type-level)
• SumDynType provides a concrete, value-level representation

It is commonly used as the backing representation (Repr) for dynamically shaped fields.

Representation Model

The Many variant is backed by a [BoundedVec], giving it vector-like semantics:

• dynamically sized (up to a bound)
• growable and shrinkable
• capacity enforced via a type-level limit

This makes SumDynType suitable for:

• flexible schemas
• deferred structure
• abstraction across boundaries where size is not fixed

Variants

• None: no value
• Some(Type): exactly one value
• Many(BoundedVec<Type, S>): multiple values with vector semantics

Type Parameters

• Type: element type
• S: type-level capacity bound

Key Property

This is a concrete (non-virtual) representation using bounded vector semantics, allowing flexible cardinality within a constrained capacity.

Default Generics

• Type = (): no meaningful value (unit type)
• S = ConstU32<0>: zero capacity, Many cannot store elements

Together, this yields a no-op, zero-capacity representation, useful as a placeholder in generic contexts.

Variants

None

Some(Type)

Many(BoundedVec<Type, S>)

Trait Implementations

impl<Type, S> Clone for SumDynType<Type, S>

where Type: Delimited + Clone, S: Get<u32> + Clone + Debug + 'static + Clone,

fn clone(&self) -> SumDynType<Type, S>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Type, S> Debug for SumDynType<Type, S>

where Type: Delimited + Debug, S: Get<u32> + Clone + Debug + 'static + Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<Type, S> Decode for SumDynType<Type, S>

where Type: Delimited + Decode, S: Get<u32> + Clone + Debug + 'static, BoundedVec<Type, S>: Decode,

fn decode<__CodecInputEdqy: Input>( __codec_input_edqy: &mut __CodecInputEdqy, ) -> Result<Self, Error>

Attempt to deserialise the value from input.

fn decode_into<I>( input: &mut I, dst: &mut MaybeUninit<Self>, ) -> Result<DecodeFinished, Error>

where I: Input,

Attempt to deserialize the value from input into a pre-allocated piece of memory.

fn skip<I>(input: &mut I) -> Result<(), Error>

where I: Input,

Attempt to skip the encoded value from input.

fn encoded_fixed_size() -> Option<usize>

Returns the fixed encoded size of the type.

impl<Type, S> Default for SumDynType<Type, S>

where Type: Delimited, S: Get<u32> + Clone + Debug + 'static,

fn default() -> SumDynType<Type, S>

Returns the “default value” for a type.

impl<Type, S> Encode for SumDynType<Type, S>

where Type: Delimited + Encode, S: Get<u32> + Clone + Debug + 'static, BoundedVec<Type, S>: Encode,

fn size_hint(&self) -> usize

If possible give a hint of expected size of the encoding.

fn encode_to<__CodecOutputEdqy: Output + ?Sized>( &self, __codec_dest_edqy: &mut __CodecOutputEdqy, )

Convert self to a slice and append it to the destination.

fn encode(&self) -> Vec<u8>

Convert self to an owned vector.

fn using_encoded<R, F>(&self, f: F) -> R

where F: FnOnce(&[u8]) -> R,

Convert self to a slice and then invoke the given closure with it.

fn encoded_size(&self) -> usize

Calculates the encoded size.

impl<Type, S> FromTag<(), NoneTag> for SumDynType<Type, S>

where Type: Delimited, S: Get<u32> + Clone + Debug + 'static,

fn from_tag(_t: ()) -> Self

impl<Type, S> FromTag<Type, SomeTag> for SumDynType<Type, S>

where Type: Delimited, S: Get<u32> + Clone + Debug + 'static,

fn from_tag(t: Type) -> Self

impl<Type, S> IntoTag<Vec<Type>, ManyTag> for SumDynType<Type, S>

where Type: Delimited, S: Get<u32> + Clone + Debug + 'static,

fn into_tag(self) -> Vec<Type>

impl<Type, S> MaxEncodedLen for SumDynType<Type, S>

where Type: Delimited + MaxEncodedLen, S: Get<u32> + Clone + Debug + 'static, BoundedVec<Type, S>: MaxEncodedLen,

fn max_encoded_len() -> usize

Upper bound, in bytes, of the maximum encoded size of this item.

impl<Type, S> PartialEq for SumDynType<Type, S>

where Type: Delimited, S: Get<u32> + Clone + Debug,

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<Type, S> TryFromTag<Vec<Type>, ManyTag> for SumDynType<Type, S>

where Type: Delimited, S: Get<u32> + Clone + Debug + 'static,

type Error = ()

fn try_from_tag(t: Vec<Type>) -> Result<Self, Self::Error>

impl<Type, S> TryIntoTag<(), NoneTag> for SumDynType<Type, S>

where Type: Delimited, S: Get<u32> + Clone + Debug + 'static,

type Error = ()

fn try_into_tag(self) -> Result<(), Self::Error>

impl<Type, S> TryIntoTag<Type, SomeTag> for SumDynType<Type, S>

where Type: Delimited, S: Get<u32> + Clone + Debug + 'static,

type Error = ()

fn try_into_tag(self) -> Result<Type, Self::Error>

impl<Type, S> TypeInfo for SumDynType<Type, S>

where Type: Delimited + TypeInfo + 'static, S: Get<u32> + Clone + Debug + 'static, BoundedVec<Type, S>: TypeInfo + 'static,

type Identity = SumDynType<Type, S>

The type identifying for which type info is provided.

fn type_info() -> Type

Returns the static type identifier for Self.

impl<Type, S> DecodeWithMemTracking for SumDynType<Type, S>

where Type: Delimited + DecodeWithMemTracking, S: Get<u32> + Clone + Debug + 'static, BoundedVec<Type, S>: DecodeWithMemTracking,

impl<Type, S> EncodeLike for SumDynType<Type, S>

where Type: Delimited + Encode, S: Get<u32> + Clone + Debug + 'static, BoundedVec<Type, S>: Encode,

impl<Type, S> Eq for SumDynType<Type, S>

where Type: Delimited, S: Get<u32> + Clone + Debug,