Trait scrypto_test::prelude::radix_engine_common::prelude::rust::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 struct
s
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 derive
d, 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§
sourcefn default() -> Self
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§
Implementors§
impl Default for &str
impl Default for &CStr
impl Default for &OsStr
impl Default for &mut str
impl Default for OnApplyCost
impl Default for BlueprintType
impl Default for FunctionAuth
impl Default for Level
impl Default for MessageV1
impl Default for MethodAuthTemplate
impl Default for NodeStateUpdates
impl Default for OuterObjectInfo
impl Default for OwnerRole
impl Default for PackageRoyaltyConfig
impl Default for PartitionDatabaseUpdates
impl Default for PartitionStateUpdates
impl Default for PrimaryRoleBadgeWithdrawAttemptState
impl Default for PrimaryRoleLockingState
impl Default for PrimaryRoleRecoveryAttemptState
impl Default for RecoveryRoleBadgeWithdrawAttemptState
impl Default for RecoveryRoleRecoveryAttemptState
impl Default for SystemLockData
impl Default for WithdrawStrategy
impl Default for Value
The default value is Value::Null
.
This is useful for handling omitted Value
fields when deserializing.
§Examples
use serde_json::Value;
#[derive(Deserialize)]
struct Settings {
level: i32,
#[serde(default)]
extras: Value,
}
let data = r#" { "level": 42 } "#;
let s: Settings = serde_json::from_str(data)?;
assert_eq!(s.level, 42);
assert_eq!(s.extras, Value::Null);
impl Default for PathArguments
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 AccountFeatureSet
impl Default for MetadataFeatureSet
impl Default for RoleAssignmentFeatureSet
impl Default for ComponentRoyaltyFeatureSet
impl Default for ComponentRoyaltyDatabaseChecker
impl Default for ResourceCounter
impl Default for ResourceDatabaseChecker
impl Default for ResourceDatabaseCheckerResults
impl Default for ResourceEventChecker
impl Default for ResourceEventCheckerResults
impl Default for RoleAssignmentDatabaseChecker
impl Default for NodeCounts
impl Default for FungibleResourceType
impl Default for FeeReserveFinalizationSummary
impl Default for SystemLoanFeeReserve
impl Default for GenericArgs
impl Default for AccessControllerFeatureSet
impl Default for AuthConfig
impl Default for AuthZone
impl Default for AuthZoneParams
impl Default for BlueprintDefinitionInit
impl Default for BlueprintEventSchemaInit
impl Default for BlueprintFunctionsSchemaInit
impl Default for BlueprintHooksInit
impl Default for BlueprintSchemaInit
impl Default for BlueprintStateSchemaInit
impl Default for BlueprintTypeSchemaInit
impl Default for BlueprintVersion
impl Default for BurnRoles<Option<AccessRule>>
impl Default for CallFrameMessage
impl Default for ComponentRoyaltyConfig
impl Default for ConsensusManagerFeatureSet
impl Default for CostingParameters
impl Default for DatabaseUpdates
impl Default for DepositRoles<Option<AccessRule>>
impl Default for EpochChangeCondition
impl Default for FeeDestination
impl Default for FeeLocks
impl Default for FeeSource
impl Default for FreezeRoles<Option<AccessRule>>
impl Default for FungibleResourceManagerFeatureSet
impl Default for FungibleResourceRoles
impl Default for FungibleVaultFeatureSet
impl Default for LegacyStateUpdates
impl Default for ManifestBuilder
impl Default for MintRoles<Option<AccessRule>>
impl Default for NodeDatabaseUpdates
impl Default for NonFungibleDataUpdateRoles<Option<AccessRule>>
impl Default for NonFungibleResourceManagerFeatureSet
impl Default for NonFungibleResourceRoles
impl Default for NonFungibleVaultFeatureSet
impl Default for PackageDefinition
impl Default for PackageFeatureSet
impl Default for PreviewFlags
impl Default for ProposalStatistic
impl Default for RecallRoles<Option<AccessRule>>
impl Default for ResourcesUsage
impl Default for RoleAssignmentInit
impl Default for RoleList
impl Default for StateUpdateSummary
impl Default for StateUpdates
impl Default for StaticRoleDefinition
impl Default for SystemStructure
impl Default for TransactionCostingParameters
impl Default for TransactionExecutionTrace
impl Default for TransactionFeeDetails
impl Default for TransactionFeeSummary
impl Default for ValidatorFeatureSet
impl Default for VaultFrozenFlag
impl Default for VmVersion
impl Default for WithdrawRoles<Option<AccessRule>>
impl Default for MultiResourcePoolFeatureSet
impl Default for OneResourcePoolFeatureSet
impl Default for TwoResourcePoolFeatureSet
impl Default for InstructionWeights
impl Default for ScryptoV1WasmValidator
impl Default for WasmiEngine
impl Default for scrypto_test::prelude::radix_engine_common::prelude::fmt::Error
impl Default for scrypto_test::prelude::radix_engine_common::prelude::prelude::Box<str>
impl Default for scrypto_test::prelude::radix_engine_common::prelude::prelude::Box<CStr>
impl Default for scrypto_test::prelude::radix_engine_common::prelude::prelude::Box<OsStr>
impl Default for LengthValidation
impl Default for String
impl Default for Decimal
impl Default for I192
impl Default for I256
impl Default for I320
impl Default for I384
impl Default for I448
impl Default for I512
impl Default for I768
impl Default for PreciseDecimal
impl Default for U192
impl Default for U256
impl Default for U320
impl Default for U384
impl Default for U448
impl Default for U512
impl Default for U768
impl Default for Global
impl Default for System
impl Default for DefaultHasher
impl Default for scrypto_test::prelude::radix_engine_common::prelude::rust::hash::RandomState
impl Default for SipHasher
impl Default for PhantomPinned
impl Default for RangeFull
impl Default for Alignment
Returns Alignment::MIN
, which is valid for any type.
impl Default for AtomicBool
impl Default for AtomicI8
impl Default for AtomicI16
impl Default for AtomicI32
impl Default for AtomicI64
impl Default for AtomicIsize
impl Default for AtomicU8
impl Default for AtomicU16
impl Default for AtomicU32
impl Default for AtomicU64
impl Default for AtomicUsize
impl Default for scrypto_test::prelude::radix_engine_common::prelude::rust::sync::Condvar
impl Default for CString
impl Default for Duration
impl Default for proc_macro::TokenStream
impl Default for OsString
impl Default for FileTimes
impl Default for std::io::util::Empty
impl Default for Sink
impl Default for PathBuf
impl Default for ExitCode
The default value is ExitCode::SUCCESS
impl Default for ExitStatus
The default value is one which indicates successful completion.
impl Default for anyhow::Chain<'_>
impl Default for CompressedEdwardsY
impl Default for EdwardsPoint
impl Default for MontgomeryPoint
impl Default for CompressedRistretto
impl Default for RistrettoPoint
impl Default for Scalar
impl Default for itoa::Buffer
impl Default for BigInt
impl Default for BigUint
impl Default for proc_macro2::TokenStream
TokenStream::default()
returns an empty stream,
i.e. this is equivalent with TokenStream::new()
.
impl Default for ryu::buffer::Buffer
impl Default for BuildMetadata
impl Default for Prerelease
impl Default for VersionReq
The default VersionReq is the same as VersionReq::STAR
.
impl Default for IgnoredAny
impl Default for Map<String, Value>
impl Default for BoundLifetimes
impl Default for Generics
impl Default for Abstract
impl Default for Add
impl Default for AddEq
impl Default for And
impl Default for AndAnd
impl Default for AndEq
impl Default for As
impl Default for Async
impl Default for At
impl Default for Auto
impl Default for Await
impl Default for Bang
impl Default for Become
impl Default for syn::token::Box
impl Default for Brace
impl Default for Bracket
impl Default for Break
impl Default for Caret
impl Default for CaretEq
impl Default for Colon2
impl Default for Colon
impl Default for Comma
impl Default for Const
impl Default for Continue
impl Default for Crate
impl Default for Default
impl Default for Div
impl Default for DivEq
impl Default for Do
impl Default for Dollar
impl Default for Dot2
impl Default for Dot3
impl Default for Dot
impl Default for DotDotEq
impl Default for Dyn
impl Default for Else
impl Default for Enum
impl Default for Eq
impl Default for EqEq
impl Default for Extern
impl Default for FatArrow
impl Default for Final
impl Default for Fn
impl Default for For
impl Default for Ge
impl Default for Group
impl Default for Gt
impl Default for If
impl Default for Impl
impl Default for In
impl Default for LArrow
impl Default for Le
impl Default for Let
impl Default for Loop
impl Default for Lt
impl Default for Macro
impl Default for Match
impl Default for Mod
impl Default for Move
impl Default for MulEq
impl Default for Mut
impl Default for Ne
impl Default for Or
impl Default for OrEq
impl Default for OrOr
impl Default for Override
impl Default for Paren
impl Default for Pound
impl Default for Priv
impl Default for Pub
impl Default for Question
impl Default for RArrow
impl Default for Ref
impl Default for Rem
impl Default for RemEq
impl Default for Return
impl Default for SelfType
impl Default for SelfValue
impl Default for Semi
impl Default for Shl
impl Default for ShlEq
impl Default for Shr
impl Default for ShrEq
impl Default for Star
impl Default for Static
impl Default for Struct
impl Default for Sub
impl Default for SubEq
impl Default for Super
impl Default for Tilde
impl Default for Trait
impl Default for Try
impl Default for Type
impl Default for Typeof
impl Default for Underscore
impl Default for Union
impl Default for Unsafe
impl Default for Unsized
impl Default for Use
impl Default for Virtual
impl Default for Where
impl Default for While
impl Default for Yield
impl Default for B0
impl Default for B1
impl Default for Z0
impl Default for Equal
impl Default for Greater
impl Default for Less
impl Default for UTerm
impl Default for Braced
impl Default for Hyphenated
impl Default for Simple
impl Default for Urn
impl Default for Uuid
impl Default for NoContext
impl Default for EntropyRng
impl Default for ThreadRng
impl Default for OsRng
impl Default for AHasher
Provides a default Hasher with fixed keys. This is typically used in conjunction with BuildHasherDefault to create [AHasher]s in order to hash the keys of the map.
Generally it is preferable to use [RandomState] instead, so that different hashmaps will have different keys. However if fixed keys are desireable this may be used instead.
§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 AlignedType
impl Default for Backoff
impl Default for BigEndian
impl Default for BlobProvider
impl Default for Builder
impl Default for Builder
impl Default for ByteClasses
impl Default for CanonicalFunctionSection
impl Default for ClassBytesRange
impl Default for ClassUnicodeRange
impl Default for CodeSection
impl Default for Collector
impl Default for ColoredString
impl Default for Component
impl Default for ComponentAliasSection
impl Default for ComponentExportSection
impl Default for ComponentImportSection
impl Default for ComponentInstanceSection
impl Default for ComponentNameSection
impl Default for ComponentType
impl Default for ComponentTypeSection
impl Default for Condvar
impl Default for Config
impl Default for Config
impl Default for Config
impl Default for Config
impl Default for Config
impl Default for Configuration
impl Default for ConfigurationBuilder
impl Default for ConstantCostRules
impl Default for CoreDumpSection
impl Default for CoreDumpStackSection
impl Default for CoreTypeSection
impl Default for DataSection
impl Default for DeliveryMode
impl Default for Eager
impl Default for ElementSection
impl Default for Engine
impl Default for Error
impl Default for ExportSection
impl Default for ExtractKind
impl Default for Extractor
impl Default for FuncValidatorAllocations
impl Default for FuncValidatorAllocations
impl Default for FunctionSection
impl Default for GlobalSection
impl Default for GroupInfo
impl Default for ImportSection
impl Default for IndirectNameMap
impl Default for InstanceSection
impl Default for InstanceType
impl Default for InvalidBufferSize
impl Default for InvalidOutputSize
impl Default for InvalidOutputSize
impl Default for Keccak224Core
impl Default for Keccak256Core
impl Default for Keccak256FullCore
impl Default for Keccak384Core
impl Default for Keccak512Core
impl Default for Lazy
impl Default for LinkingSection
impl Default for LittleEndian
impl Default for LookMatcher
impl Default for LookSet
impl Default for LookSet
impl Default for MacError
impl Default for ManifestIdAllocator
impl Default for ManifestObjectNames
impl Default for ManifestValidator
impl Default for MatchKind
impl Default for MemorySection
impl Default for MessageValidationConfig
impl Default for MockBlobProvider
impl Default for Module
impl Default for ModuleInfo
impl Default for ModuleType
impl Default for NameMap
impl Default for NameResolver
impl Default for NameSection
impl Default for Null
impl Default for Once
impl Default for OnceBool
impl Default for OnceNonZeroUsize
impl Default for Pages
impl Default for Parker
impl Default for Parser
impl Default for Parser
impl Default for ParserBuilder
impl Default for ParserBuilder
impl Default for PatternID
impl Default for ProducersField
impl Default for ProducersSection
impl Default for PublicKey
impl Default for PublicKey
impl Default for PublicKey
impl Default for RandomState
impl Default for RecoverableSignature
impl Default for RegexSet
impl Default for RegexSet
impl Default for Secp256k1<All>
impl Default for SecretKey
impl Default for SecretKey
impl Default for Sha3_224Core
impl Default for Sha3_256Core
impl Default for Sha3_384Core
impl Default for Sha3_512Core
impl Default for Sha224
impl Default for Sha256
impl Default for Sha384
impl Default for Sha512
impl Default for Sha512Trunc224
impl Default for Sha512Trunc256
impl Default for Shake128Core
impl Default for Shake256Core
impl Default for ShouldColorize
impl Default for SmallIndex
impl Default for SpinWait
impl Default for StackLimits
impl Default for StateID
impl Default for SymbolTable
impl Default for TableSection
impl Default for TagSection
impl Default for ThreadPool
Create a thread pool with one thread per CPU. On machines with hyperthreading, this will create one thread per hyperthread.
impl Default for TranslatorBuilder
impl Default for TypeSection
impl Default for UnparkResult
impl Default for UntypedValue
impl Default for Validator
impl Default for Validator
impl Default for WaitGroup
impl Default for WasmFeatures
impl Default for WasmFeatures
impl Default for WhichCaptures
impl Default for blst_fp
impl Default for blst_fp2
impl Default for blst_fp6
impl Default for blst_fp12
impl Default for blst_fr
impl Default for blst_p1
impl Default for blst_p1_affine
impl Default for blst_p2
impl Default for blst_p2_affine
impl Default for blst_pairing
impl Default for blst_scalar
impl Default for blst_uniq
impl Default for u5
impl Default for vec128_storage
impl Default for vec256_storage
impl Default for vec512_storage
impl<'a> Default for TransactionReceiptDisplayContext<'a>
impl<'a> Default for ManifestValueDisplayContext<'a>
impl<'a> Default for ScryptoValueDisplayContext<'a>
impl<'a> Default for PrettyFormatter<'a>
impl<'a> Default for DecompilationContext<'a>
impl<'a> Default for ManifestDecompilationDisplayContext<'a>
impl<'a> Default for Select<'a>
impl<'a, K, V> Default for scrypto_test::prelude::radix_engine_common::prelude::btree_map::Iter<'a, K, V>where
K: 'a,
V: 'a,
impl<'a, K, V> Default for scrypto_test::prelude::radix_engine_common::prelude::btree_map::IterMut<'a, K, V>where
K: 'a,
V: 'a,
impl<'a, T> Default for OnceRef<'a, T>
impl<'m> Default for ArrayData<'m>
impl<'m> Default for MapData<'m>
impl<'s> Default for EnumVariantData<'s>
impl<'s> Default for TupleData<'s>
impl<A> Default for SystemDatabaseChecker<A>where
A: ApplicationChecker + Default,
impl<A> Default for SmallVec<A>where
A: Array,
impl<A, B> Default for scrypto_test::prelude::radix_engine_common::prelude::rust::iter::Chain<A, B>
impl<B> Default for Cow<'_, B>
impl<BlockSize> Default for BlockBuffer<BlockSize>
impl<BlockSize, Kind> Default for BlockBuffer<BlockSize, Kind>
impl<H> Default for BuildHasherDefault<H>
impl<I> Default for Cloned<I>where
I: Default,
impl<I> Default for Copied<I>where
I: Default,
impl<I> Default for Enumerate<I>where
I: Default,
impl<I> Default for Flatten<I>
impl<I> Default for Fuse<I>where
I: Default,
impl<I> Default for Rev<I>where
I: Default,
impl<Idx> Default for scrypto_test::prelude::radix_engine_common::prelude::rust::ops::Range<Idx>where
Idx: Default,
impl<Idx, T> Default for Arena<Idx, T>
impl<Idx, T> Default for ComponentVec<Idx, T>
impl<Idx, T> Default for DedupArena<Idx, T>
impl<K, V> Default for &scrypto_test::prelude::radix_engine_common::prelude::indexmap::map::Slice<K, V>
impl<K, V> Default for &Slice<K, V>
impl<K, V> Default for &mut scrypto_test::prelude::radix_engine_common::prelude::indexmap::map::Slice<K, V>
impl<K, V> Default for &mut Slice<K, V>
impl<K, V> Default for KeyValueStoreInit<K, V>
impl<K, V> Default for scrypto_test::prelude::radix_engine_common::prelude::btree_map::Keys<'_, K, V>
impl<K, V> Default for scrypto_test::prelude::radix_engine_common::prelude::btree_map::Range<'_, K, V>
impl<K, V> Default for scrypto_test::prelude::radix_engine_common::prelude::btree_map::Values<'_, K, V>
impl<K, V> Default for BTreeMap<K, V>
impl<K, V> Default for scrypto_test::prelude::radix_engine_common::prelude::prelude::Box<Slice<K, V>>
impl<K, V> Default for scrypto_test::prelude::radix_engine_common::prelude::prelude::Box<Slice<K, V>>
impl<K, V> Default for NonIterMap<K, V>
impl<K, V> Default for CacheBuilder<K, V, Cache<K, V>>
impl<K, V> Default for CacheBuilder<K, V, Cache<K, V>>
impl<K, V> Default for IndexMap<K, V>
impl<K, V> Default for IntoIter<K, V>
impl<K, V> Default for IntoKeys<K, V>
impl<K, V> Default for IntoValues<K, V>
impl<K, V> Default for Iter<'_, K, V>
impl<K, V> Default for IterMut<'_, K, V>
impl<K, V> Default for Keys<'_, K, V>
impl<K, V> Default for Values<'_, K, V>
impl<K, V> Default for ValuesMut<'_, K, V>
impl<K, V, A> Default for scrypto_test::prelude::radix_engine_common::prelude::btree_map::IntoIter<K, V, A>
impl<K, V, A> Default for scrypto_test::prelude::radix_engine_common::prelude::btree_map::IntoKeys<K, V, A>
impl<K, V, A> Default for scrypto_test::prelude::radix_engine_common::prelude::btree_map::IntoValues<K, V, A>
impl<K, V, S> Default for scrypto_test::prelude::radix_engine_common::prelude::hash_map::ext_HashMap<K, V, S>where
S: Default,
impl<K, V, S> Default for scrypto_test::prelude::radix_engine_common::prelude::indexmap::IndexMap<K, V, S>where
S: Default,
impl<K, V, S> Default for indexmap::map::IndexMap<K, V, S>where
S: Default,
impl<K, V, S> Default for IndexMap<K, V, S>where
S: Default,
impl<K, V, S, A> Default for HashMap<K, V, S, A>
impl<K, V, S, A> Default for HashMap<K, V, S, A>
impl<K, V, S, A> Default for HashMap<K, V, S, A>
impl<R, G, T> Default for ReentrantMutex<R, G, T>
impl<R, T> Default for Mutex<R, T>
impl<R, T> Default for RwLock<R, T>
impl<S> Default for VersionedSchema<S>where
S: CustomSchema,
impl<S> Default for SchemaV1<S>where
S: CustomSchema,
impl<T> Default for &[T]
impl<T> Default for &scrypto_test::prelude::radix_engine_common::prelude::indexmap::set::Slice<T>
impl<T> Default for &Slice<T>
impl<T> Default for &mut [T]
impl<T> Default for Option<T>
impl<T> Default for [T; 0]
impl<T> Default for [T; 1]where
T: Default,
impl<T> Default for [T; 2]where
T: Default,
impl<T> Default for [T; 3]where
T: Default,
impl<T> Default for [T; 4]where
T: Default,
impl<T> Default for [T; 5]where
T: Default,
impl<T> Default for [T; 6]where
T: Default,
impl<T> Default for [T; 7]where
T: Default,
impl<T> Default for [T; 8]where
T: Default,
impl<T> Default for [T; 9]where
T: Default,
impl<T> Default for [T; 10]where
T: Default,
impl<T> Default for [T; 11]where
T: Default,
impl<T> Default for [T; 12]where
T: Default,
impl<T> Default for [T; 13]where
T: Default,
impl<T> Default for [T; 14]where
T: Default,
impl<T> Default for [T; 15]where
T: Default,
impl<T> Default for [T; 16]where
T: Default,
impl<T> Default for [T; 17]where
T: Default,
impl<T> Default for [T; 18]where
T: Default,
impl<T> Default for [T; 19]where
T: Default,
impl<T> Default for [T; 20]where
T: Default,
impl<T> Default for [T; 21]where
T: Default,
impl<T> Default for [T; 22]where
T: Default,
impl<T> Default for [T; 23]where
T: Default,
impl<T> Default for [T; 24]where
T: Default,
impl<T> Default for [T; 25]where
T: Default,
impl<T> Default for [T; 26]where
T: Default,
impl<T> Default for [T; 27]where
T: Default,
impl<T> Default for [T; 28]where
T: Default,
impl<T> Default for [T; 29]where
T: Default,
impl<T> Default for [T; 30]where
T: Default,
impl<T> Default for [T; 31]where
T: Default,
impl<T> Default for [T; 32]where
T: Default,
impl<T> Default for (T₁, T₂, …, Tₙ)where
T: Default,
This trait is implemented for tuples up to twelve items long.