EnvSourceChain

rush_var::env_source

Struct EnvSourceChain 

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pub struct EnvSourceChain<A, B> {
    pub primary: A,
    pub fallback: B,
}
Expand description

链式环境变量源：优先查询 primary，没有再查 fallback。 常用于“临时变量+系统变量”的多层环境方案。

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§primary: A

主查找源（优先）

§fallback: B

备选查找源（兜底）

Trait Implementations§

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impl<A: EnvSource, B: EnvSource> EnvSource for EnvSourceChain<A, B>

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fn get(&self, key: &str) -> Option<String>

获取指定 key 的变量值，如果不存在则返回 None。

Auto Trait Implementations§

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impl<A, B> Freeze for EnvSourceChain<A, B>
where A: Freeze, B: Freeze,

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impl<A, B> RefUnwindSafe for EnvSourceChain<A, B>
where A: RefUnwindSafe, B: RefUnwindSafe,

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impl<A, B> Send for EnvSourceChain<A, B>
where A: Send, B: Send,

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impl<A, B> Sync for EnvSourceChain<A, B>
where A: Sync, B: Sync,

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impl<A, B> Unpin for EnvSourceChain<A, B>
where A: Unpin, B: Unpin,

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impl<A, B> UnwindSafe for EnvSourceChain<A, B>
where A: UnwindSafe, B: 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, 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.