Struct ConfigBag

pub struct ConfigBag { /* private fields */ }

Layered configuration structure

See the module docs for more documentation.

Implementations

impl ConfigBag

pub fn base() -> Self

Create a new config bag “base”.

pub fn of_layers(layers: impl IntoIterator<Item = Layer>) -> Self

Create a ConfigBag consisting of the given layers.

pub fn push_layer(&mut self, layer: Layer) -> &mut Self

Add the given layer to the config bag.

pub fn push_shared_layer(&mut self, layer: FrozenLayer) -> &mut Self

Add a frozen/shared layer to the config bag.

pub fn interceptor_state(&mut self) -> &mut Layer

Return a reference to the mutable interceptor state.

pub fn load<T: Storable>(&self) -> <T::Storer as Store>::ReturnedType<'_>

Load a value (or values) of type T depending on how T implements Storable

pub fn get_mut<T>(&mut self) -> Option<&mut T>

where T: Storable<Storer = StoreReplace<T>> + Send + Sync + Debug + Clone + 'static,

Return a mutable reference to T if it is stored in the top layer of the bag

pub fn get_mut_or_default<T>(&mut self) -> &mut T

where T: Storable<Storer = StoreReplace<T>> + Send + Sync + Debug + Clone + Default + 'static,

Returns a mutable reference to T if it is stored in the top layer of the bag

• If T is in a deeper layer of the bag, that value will be cloned and inserted into the top layer
• If T is not present in the bag, the Default implementation will be used.

pub fn get_mut_or_else<T>(&mut self, default: impl Fn() -> T) -> &mut T

where T: Storable<Storer = StoreReplace<T>> + Send + Sync + Debug + Clone + 'static,

Returns a mutable reference to T if it is stored in the top layer of the bag

• If T is in a deeper layer of the bag, that value will be cloned and inserted into the top layer
• If T is not present in the bag, default will be used to construct a new value

pub fn with_fn( self, name: impl Into<Cow<'static, str>>, next: impl Fn(&mut Layer), ) -> ConfigBag

Add another layer to this configuration bag

Hint: If you want to re-use this layer, call freeze first.

Examples

use aws_smithy_types::config_bag::{ConfigBag, Layer, Storable, StoreReplace};

#[derive(Debug, Eq, PartialEq)]
struct ExampleStr(&'static str);
impl Storable for ExampleStr {
    type Storer = StoreReplace<Self>;
}

#[derive(Debug, Eq, PartialEq)]
struct ExampleInt(i32);
impl Storable for ExampleInt {
    type Storer = StoreReplace<Self>;
}

let mut bag = ConfigBag::base();
bag = bag.with_fn("first", |layer: &mut Layer| { layer.store_put(ExampleStr("a")); });

// We can now load the example string out
assert_eq!(bag.load::<ExampleStr>(), Some(&ExampleStr("a")));

// But there isn't a number stored in the bag yet
assert_eq!(bag.load::<ExampleInt>(), None);

// Add a layer with an example int
bag = bag.with_fn("second", |layer: &mut Layer| { layer.store_put(ExampleInt(1)); });

// Now the example int can be retrieved
assert_eq!(bag.load::<ExampleInt>(), Some(&ExampleInt(1)));

pub fn add_layer(self, name: impl Into<Cow<'static, str>>) -> ConfigBag

Add a new layer with name after freezing the top layer so far

pub fn sourced_get<T: Store>(&self) -> T::ReturnedType<'_>

Return a value (or values) of type T depending on how it has been stored in a ConfigBag

It flexibly chooses to return a single value vs. an iterator of values depending on how T implements a Store trait.

Trait Implementations

impl Debug for ConfigBag

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.