Struct Witness

pub struct Witness<WitnessData>(/* private fields */);

The Witness strategy is an inspect strategy, which gets the specified WitnessData from the asset.

The WitnessData can be anything descriptive about the asset that helps perform a related operation. For instance, a witness could be required to destroy an NFT collection because the corresponding extrinsic’s weight couldn’t be known ahead of time without providing, for example, the number of items within the collection. In this case, the number of items is the witness data. The said extrinsic, in turn, could use the destroy operation with the WithWitness strategy, which will compare the provided witness with the actual chain state before attempting the collection destruction.

Trait Implementations

impl<WitnessData: Clone> Clone for Witness<WitnessData>

fn clone(&self) -> Witness<WitnessData>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<WitnessData> Debug for Witness<WitnessData>

where WitnessData: Debug,

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

Formats the value using the given formatter.

impl<WitnessData> Decode for Witness<WitnessData>

where PhantomData<WitnessData>: 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<WitnessData> Default for Witness<WitnessData>

fn default() -> Self

Returns the “default value” for a type.

impl<WitnessData> Encode for Witness<WitnessData>

where PhantomData<WitnessData>: 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<__CodecOutputReturn, __CodecUsingEncodedCallback: FnOnce(&[u8]) -> __CodecOutputReturn>( &self, f: __CodecUsingEncodedCallback, ) -> __CodecOutputReturn

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

fn encoded_size(&self) -> usize

Calculates the encoded size.

impl<WitnessData> InspectStrategy for Witness<WitnessData>

type Value = WitnessData

The value representing the asset’s state related to this InspectStrategy.

impl<WitnessData> MaxEncodedLen for Witness<WitnessData>

where PhantomData<WitnessData>: MaxEncodedLen,

fn max_encoded_len() -> usize

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

impl<WitnessData: PartialEq> PartialEq for Witness<WitnessData>

fn eq(&self, other: &Witness<WitnessData>) -> 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<WitnessData> TypeInfo for Witness<WitnessData>

where PhantomData<WitnessData>: TypeInfo + 'static, WitnessData: TypeInfo + 'static,

type Identity = Witness<WitnessData>

The type identifying for which type info is provided.

fn type_info() -> Type

Returns the static type identifier for Self.

impl<WitnessData> EncodeLike for Witness<WitnessData>

where PhantomData<WitnessData>: Encode,

impl<WitnessData: Eq> Eq for Witness<WitnessData>

impl<WitnessData> StructuralPartialEq for Witness<WitnessData>