Struct scale_info::Field

pub struct Field<T: Form = MetaForm> { /* fields omitted */ }

A field of a struct-like data type.

Name is optional so it can represent both named and unnamed fields.

This can be a named field of a struct type or an enum struct variant, or an unnamed field of a tuple struct.

Type name

The type_name field contains a string which is the name of the type of the field as it appears in the source code. The exact contents and format of the type name are not specified, but in practice will be the name of any valid type for a field e.g.

• Concrete types e.g "u32", "bool", "Foo" etc.
• Type parameters e.g "T", "U"
• Generic types e.g "Vec<u32>", "Vec<T>"
• Associated types e.g. "T::MyType", "<T as MyTrait>::MyType"
• Type aliases e.g. "MyTypeAlias", "MyTypeAlias<T>"
• Other built in Rust types e.g. arrays, references etc.

Note that the type name doesn't correspond to the underlying type of the field, unless using a concrete type directly. Any given type may be referred to by multiple field type names, when using generic type parameters and type aliases.

This is intended for informational and diagnostic purposes only. Although it is possible to infer certain properties e.g. whether a type name is a type alias, there are no guarantees provided, and the type name representation may change.

Implementations

impl Field

pub fn new(
    name: Option<&'static str>,
    ty: MetaType,
    type_name: &'static str
) -> Self

Creates a new field.

Use this constructor if you want to instantiate from a given meta type.

pub fn named_of<T: ?Sized>(name: &'static str, type_name: &'static str) -> Field where
    T: TypeInfo + 'static, 

Creates a new named field.

Use this constructor if you want to instantiate from a given compile-time type.

pub fn unnamed_of<T: ?Sized>(type_name: &'static str) -> Field where
    T: TypeInfo + 'static, 

Creates a new unnamed field.

Use this constructor if you want to instantiate an unnamed field from a given compile-time type.

impl<T> Field<T> where
    T: Form, 

pub fn name(&self) -> Option<&T::String>

Returns the name of the field. None for unnamed fields.

pub fn ty(&self) -> &T::Type

Returns the type of the field.

pub fn type_name(&self) -> &T::String

Returns a string which is the name of the type of the field as it appears in the source code. The exact contents and format of the type name are not specified, but in practice will be the name of any valid type for a field. This is intended for informational and diagnostic purposes only.

Trait Implementations

impl<T: Clone + Form> Clone for Field<T> where
    T::String: Clone,
    T::Type: Clone,
    T::String: Clone, 

fn clone(&self) -> Field<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Debug + Form> Debug for Field<T> where
    T::String: Debug,
    T::Type: Debug,
    T::String: Debug, 

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

Formats the value using the given formatter.

impl<T: Form> Decode for Field<T> where
    Option<T::String>: Decode,
    Option<T::String>: Decode,
    T::Type: Decode,
    T::Type: Decode,
    T::String: Decode,
    T::String: Decode, 

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

Attempt to deserialise the value from input.

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

Attempt to skip the encoded value from input.

pub fn encoded_fixed_size() -> Option<usize>

Returns the fixed encoded size of the type.

impl<T: Form> Encode for Field<T> where
    Option<T::String>: Encode,
    Option<T::String>: Encode,
    T::Type: Encode,
    T::Type: Encode,
    T::String: Encode,
    T::String: Encode, 

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

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

pub fn size_hint(&self) -> usize

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

pub fn encode(&self) -> Vec<u8, Global>

Convert self to an owned vector.

pub 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.

pub fn encoded_size(&self) -> usize

Calculates the encoded size.

impl<T: Form> EncodeLike<Field<T>> for Field<T> where
    Option<T::String>: Encode,
    Option<T::String>: Encode,
    T::Type: Encode,
    T::Type: Encode,
    T::String: Encode,
    T::String: Encode, 

impl<T: Eq + Form> Eq for Field<T> where
    T::String: Eq,
    T::Type: Eq,
    T::String: Eq, 

impl IntoPortable for Field

type Output = Field<PortableForm>

The portable version of Self.

fn into_portable(self, registry: &mut Registry) -> Self::Output

Convert self to the portable form by using the registry for caching.

impl<T: Ord + Form> Ord for Field<T> where
    T::String: Ord,
    T::Type: Ord,
    T::String: Ord, 

fn cmp(&self, other: &Field<T>) -> Ordering

This method returns an Ordering between self and other.

#[must_use]pub fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]pub fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]pub fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<T: PartialEq + Form> PartialEq<Field<T>> for Field<T> where
    T::String: PartialEq,
    T::Type: PartialEq,
    T::String: PartialEq, 

fn eq(&self, other: &Field<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Field<T>) -> bool

This method tests for !=.

impl<T: PartialOrd + Form> PartialOrd<Field<T>> for Field<T> where
    T::String: PartialOrd,
    T::Type: PartialOrd,
    T::String: PartialOrd, 

fn partial_cmp(&self, other: &Field<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Field<T>) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Field<T>) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Field<T>) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Field<T>) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: Form> StructuralEq for Field<T>

impl<T: Form> StructuralPartialEq for Field<T>