Struct Singleton

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pub struct Singleton<'a, T>{ /* private fields */ }
๐Ÿ‘ŽDeprecated: The crate cosmwasm-storage is unmaintained and will be removed in CosmWasm 2.0. Please consider migrating to cw-storage-plus or simple cosmwasm-std storage calls.
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Singleton effectively combines PrefixedStorage with TypedStorage to work on a single storage key. It performs the to_length_prefixed transformation on the given name to ensure no collisions, and then provides the standard TypedStorage accessors, without requiring a key (which is defined in the constructor)

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impl<'a, T> Singleton<'a, T>

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pub fn new(storage: &'a mut dyn Storage, key: &[u8]) -> Self

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pub fn save(&mut self, data: &T) -> StdResult<()>

save will serialize the model and store, returns an error on serialization issues

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pub fn remove(&mut self)

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pub fn load(&self) -> StdResult<T>

load will return an error if no data is set at the given key, or on parse error

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pub fn may_load(&self) -> StdResult<Option<T>>

may_load will parse the data stored at the key if present, returns Ok(None) if no data there. returns an error on issues parsing

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pub fn update<A, E>(&mut self, action: A) -> Result<T, E>
where A: FnOnce(T) -> Result<T, E>, E: From<StdError>,

update will load the data, perform the specified action, and store the result in the database. This is shorthand for some common sequences, which may be useful

This is the least stable of the APIs, and definitely needs some usage

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impl<'a, T> Freeze for Singleton<'a, T>

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impl<'a, T> !RefUnwindSafe for Singleton<'a, T>

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impl<'a, T> !Send for Singleton<'a, T>

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impl<'a, T> !Sync for Singleton<'a, T>

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impl<'a, T> Unpin for Singleton<'a, T>
where T: Unpin,

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impl<'a, T> !UnwindSafe for Singleton<'a, T>

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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<U> As for U

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fn as_<T>(self) -> T
where T: CastFrom<U>,

Casts self to type T. The semantics of numeric casting with the as operator are followed, so <T as As>::as_::<U> can be used in the same way as T as U for numeric conversions. 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> Same for T

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type Output = T

Should always be Self
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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.