Trait ibc_core::primitives::prelude::Default

1.0.0 · source ·

pub trait Default: Sized {
    // Required method
    fn default() -> Self;
}

Expand description

A trait for giving a type a useful default value.

Sometimes, you want to fall back to some kind of default value, and don’t particularly care what it is. This comes up often with structs that define a set of options:

struct SomeOptions {
    foo: i32,
    bar: f32,
}

How can we define some default values? You can use Default:

#[derive(Default)]
struct SomeOptions {
    foo: i32,
    bar: f32,
}

fn main() {
    let options: SomeOptions = Default::default();
}

Now, you get all of the default values. Rust implements Default for various primitives types.

If you want to override a particular option, but still retain the other defaults:

fn main() {
    let options = SomeOptions { foo: 42, ..Default::default() };
}

§Derivable

This trait can be used with #[derive] if all of the type’s fields implement Default. When derived, it will use the default value for each field’s type.

§`enum`s

When using #[derive(Default)] on an enum, you need to choose which unit variant will be default. You do this by placing the #[default] attribute on the variant.

#[derive(Default)]
enum Kind {
    #[default]
    A,
    B,
    C,
}

You cannot use the #[default] attribute on non-unit or non-exhaustive variants.

§How can I implement `Default`?

Provide an implementation for the default() method that returns the value of your type that should be the default:

enum Kind {
    A,
    B,
    C,
}

impl Default for Kind {
    fn default() -> Self { Kind::A }
}

§Examples

#[derive(Default)]
struct SomeOptions {
    foo: i32,
    bar: f32,
}

Required Methods§

source

fn default() -> Self

Returns the “default value” for a type.

Default values are often some kind of initial value, identity value, or anything else that may make sense as a default.

§Examples

Using built-in default values:

let i: i8 = Default::default();
let (x, y): (Option<String>, f64) = Default::default();
let (a, b, (c, d)): (i32, u32, (bool, bool)) = Default::default();

Making your own:

enum Kind {
    A,
    B,
    C,
}

impl Default for Kind {
    fn default() -> Self { Kind::A }
}

Object Safety§

This trait is not object safe.

Implementors§

source §

impl Default for &str

1.10.0 · source§

impl Default for ibc_core::channel::types::Version

The default version is empty (unspecified).

Returns Alignment::MIN, which is valid for any type.

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impl Default for core::time::Duration

1.28.0 · source§

impl Default for DefaultHasher

1.7.0 · source§

impl Default for std::io::util::Empty

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impl Default for ExitCode

The default value is ExitCode::SUCCESS

1.73.0 · source§

impl Default for ExitStatus

The default value is one which indicates successful completion.

§Example

use std::hash::BuildHasherDefault;
use ahash::{AHasher, RandomState};
use std::collections::HashMap;

let mut map: HashMap<i32, i32, BuildHasherDefault<AHasher>> = HashMap::default();
map.insert(12, 34);

impl Default for Minute

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impl Default for MonthRepr

Creates a modifier that indicates the value uses the Numerical representation.

Creates a modifier that indicates the value only uses a sign for negative values and is padded with zeroes.

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impl Default for OffsetMinute

Creates a modifier that indicates the value is padded with zeroes.

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impl Default for OffsetSecond

Creates a modifier that indicates the value is padded with zeroes.

impl Default for Subsecond

Creates a modifier that indicates the stringified value contains one or more digits.

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impl Default for SubsecondDigits

Creates a modifier that indicates the stringified value contains one or more digits.

impl Default for UnixTimestampPrecision

Creates a modifier that indicates the value represents the number of seconds since the Unix epoch.

Creates a modifier that indicates that the value is padded with zeroes and uses the Iso representation.

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impl Default for WeekNumberRepr

Creates a modifier that indicates that the value uses the Iso representation.

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impl Default for Weekday

Creates a modifier that indicates the value uses the Long representation and is case-sensitive when parsing. If the representation is changed to a numerical one, the instance defaults to one-based indexing.

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impl Default for WeekdayRepr

Creates a modifier that indicates the value uses the Long representation.

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impl Default for WeightedVoteOption

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impl Default for WeightedVoteOption

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impl Default for Year

Creates a modifier that indicates the value uses the Full representation, is padded with zeroes, uses the Gregorian calendar as its base, and only includes the year’s sign if necessary.

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impl Default for YearRepr

impl<T> Default for (T₁, T₂, …, Tₙ)
where T: Default,

Trait ibc_core::primitives::prelude::Default

§Derivable

§enums

§How can I implement Default?

§Examples

Required Methods§

fn default() -> Self

§Examples

Object Safety§

Implementors§

impl Default for &str

impl Default for &CStr

impl Default for &OsStr

impl Default for &mut str

impl Default for ibc_core::channel::types::channel::Order

impl Default for ibc_core::channel::types::proto::v1::Order

impl Default for ResponseResultType

impl Default for ibc_core::channel::types::proto::v1::State

impl Default for TimeoutHeight

impl Default for HashOp

impl Default for LengthOp

impl Default for ibc_core::connection::types::proto::v1::State

impl Default for Value

§Examples

impl Default for bool

impl Default for char

impl Default for f32

impl Default for f64

impl Default for i8

impl Default for i16

impl Default for i32

impl Default for i64

impl Default for i128

impl Default for isize

impl Default for u8

impl Default for u16

impl Default for u32

impl Default for u64

impl Default for u128

impl Default for ()

impl Default for usize

impl Default for Acknowledgement

impl Default for Channel

impl Default for ibc_core::channel::types::proto::v1::Counterparty

impl Default for ibc_core::channel::types::proto::v1::GenesisState

impl Default for IdentifiedChannel

impl Default for MsgAcknowledgement

impl Default for MsgAcknowledgementResponse

impl Default for MsgChannelCloseConfirm

impl Default for MsgChannelCloseConfirmResponse

impl Default for MsgChannelCloseInit

impl Default for MsgChannelCloseInitResponse

impl Default for MsgChannelOpenAck

impl Default for MsgChannelOpenAckResponse

impl Default for MsgChannelOpenConfirm

impl Default for MsgChannelOpenConfirmResponse

impl Default for MsgChannelOpenInit

impl Default for MsgChannelOpenInitResponse

impl Default for MsgChannelOpenTry

impl Default for MsgChannelOpenTryResponse

impl Default for MsgRecvPacket

impl Default for MsgRecvPacketResponse

impl Default for MsgTimeout

impl Default for MsgTimeoutOnClose

impl Default for MsgTimeoutOnCloseResponse

impl Default for MsgTimeoutResponse

impl Default for ibc_core::channel::types::proto::v1::Packet

impl Default for PacketId

impl Default for PacketSequence

impl Default for PacketState

impl Default for QueryChannelClientStateRequest

impl Default for QueryChannelClientStateResponse

impl Default for QueryChannelConsensusStateRequest

impl Default for QueryChannelConsensusStateResponse

impl Default for QueryChannelRequest

impl Default for QueryChannelResponse

impl Default for QueryChannelsRequest

impl Default for QueryChannelsResponse

impl Default for QueryConnectionChannelsRequest

impl Default for QueryConnectionChannelsResponse

§`enum`s

§How can I implement `Default`?