pub enum OptionalArg<T> {
    Some(T),
    None,
}
Expand description

A smart contract argument or result that can be missing.

If arguments stop before this argument, None will be returned. As an endpoint result, the contract decides if it produces it or not.

As a principle, optional arguments or results should come last, otherwise there is ambiguity as to how to interpret what comes after.

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Some(T)

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None

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impl<T> OptionalArg<T>

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pub fn into_option(self) -> Option<T>

Trait Implementations§

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impl<T: Clone> Clone for OptionalArg<T>

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

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<T> ContractCallArg for &OptionalArg<T>
where T: ContractCallArg,

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impl<T> ContractCallArg for OptionalArg<T>
where T: ContractCallArg,

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impl<T> DynArg for OptionalArg<T>
where T: DynArg,

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fn dyn_load<I: DynArgInput>(loader: &mut I, arg_id: ArgId) -> Self

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impl<T> EndpointResult for OptionalArg<T>
where T: EndpointResult,

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type DecodeAs = OptionalArg<<T as EndpointResult>::DecodeAs>

Indicates how the result of the endpoint can be interpreted when called via proxy. Self for most types.
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fn finish<FA>(&self)

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impl<T> From<Option<T>> for OptionalArg<T>

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fn from(v: Option<T>) -> Self

Converts to this type from the input type.
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impl<T: TypeAbi> TypeAbi for OptionalArg<T>

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fn type_name() -> String

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fn provide_type_descriptions<TDC: TypeDescriptionContainer>( accumulator: &mut TDC )

A type can provide more than its own description. For instance, a struct can also provide the descriptions of the type of its fields. TypeAbi doesn’t care for the exact accumulator type, which is abstracted by the TypeDescriptionContainer trait.

Auto Trait Implementations§

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impl<T> RefUnwindSafe for OptionalArg<T>
where T: RefUnwindSafe,

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impl<T> Send for OptionalArg<T>
where T: Send,

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impl<T> Sync for OptionalArg<T>
where T: Sync,

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impl<T> Unpin for OptionalArg<T>
where T: Unpin,

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impl<T> UnwindSafe for OptionalArg<T>
where T: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.