Struct composable::dependencies::Dependency

pub struct Dependency<T: 'static> { /* private fields */ }

A wrapper type for accessing dependencies

Implementations

impl<T> Dependency<T>

• The methods of Dependency are very similar to those of std::option::Option, as dependencies are optionally present.
• However, a Dependency on a type with a DependencyDefault also implements the AsRef, Deref and Borrow traits. Event if a value has not been explicitly registered for it, the Dependency will still be able to as_ref, deref and borrow this default value.

pub fn new() -> Self

Creates a optional reference to the dependency of type T.

pub fn is_some(&self) -> bool

Returns true if the dependency is a Some value.

pub fn is_some_and(&self, f: impl FnOnce(&T) -> bool) -> bool

Returns true if the dependency is a Some and the value inside of it matches a predicate.

pub fn is_none(&self) -> bool

Returns true if the dependency is a None value.

pub fn as_slice(&self) -> &[T]

Returns a slice of the dependency value, if any. If this is None, an empty slice is returned.

pub fn iter(&self) -> Iter<'_, T>

Returns an iterator over the dependency value, if any.

pub fn expect(&self, msg: &str) -> &T

Returns the dependency Some value.

Panics

Panics if the dependency is a None with a custom panic message provided by msg.

pub fn unwrap(&self) -> &T

Returns the contained Some value.

Panics

Panics if the dependency value equals None.

pub fn unwrap_or(&self, default: T) -> Ref<'_, T>

Returns the dependency Some value or a provided default.

pub fn unwrap_or_else<F>(&self, f: F) -> Ref<'_, T>

where F: FnOnce() -> T,

Returns the dependency Some value or computes it from a closure.

pub fn unwrap_or_default(&self) -> Ref<'_, T>

where T: Default,

Returns the dependency Some value or a default.

pub fn map<U, F>(&self, f: F) -> Option<U>

where F: FnOnce(&T) -> U,

Maps to Option<U> by applying a function to a dependency value (if Some) or returns None (if None).

pub fn inspect<F>(&self, f: F) -> Option<&T>

where F: FnOnce(&T),

Calls the provided closure with a reference to the dependency value (if Some).

pub fn map_or<U, F>(&self, default: U, f: F) -> U

where F: FnOnce(&T) -> U,

Returns the provided default result (if None), or applies a function to the dependency value (if Some).

pub fn map_or_else<U, D, F>(&self, default: D, f: F) -> U

where D: FnOnce() -> U, F: FnOnce(&T) -> U,

Computes a default function result (if None), or applies a different function to the dependency value (if Some).

pub fn ok_or<E>(&self, err: E) -> Result<&T, E>

Transforms into a Result<&T, E>, mapping Some to Ok and None to Err.

pub fn ok_or_else<E, F>(&self, err: F) -> Result<&T, E>

where F: FnOnce() -> E,

Transforms into a Result<&T, E>, mapping Some to Ok and None to Err.

pub fn as_deref(&self) -> Option<&T>

Converts into a Option<&T>.

Note

This is the preferred method for producing an Option to use with the question mark operator.¹

---

1. Once the Try trait is stabilized it will be implemented for Dependency. ↩

pub fn and<U>(&self, rhs: Option<U>) -> Option<U>

Returns None if the dependency is None, otherwise returns rhs.

pub fn and_then<U, F: FnOnce(&T) -> Option<U>>(&self, f: F) -> Option<U>

Returns None if the dependency is None, otherwise calls f with the dependency value and returns the result.

pub fn filter<P>(&self, predicate: P) -> Option<&T>

where P: FnOnce(&T) -> bool,

Returns None if the dependency is None, otherwise calls predicate with the dependency value and returns:

pub fn or(&self, rhs: Option<T>) -> Option<Ref<'_, T>>

Returns the dependency if it is Some, otherwise returns rhs.

pub fn or_else<F>(&self, f: F) -> Option<Ref<'_, T>>

where F: FnOnce() -> Option<T>,

Returns the dependency if it is Some, otherwise calls f and returns the result.

pub fn xor(&self, rhs: Option<T>) -> Option<Ref<'_, T>>

Returns Some if only one of

• the dependency, or
• rhs

is Some, otherwise returns None.

pub fn copied(&self) -> Option<T>

where T: Copy,

Maps the dependency to an Option<T> by copying the contents of the option.

pub fn cloned(&self) -> Option<T>

where T: Clone,

Maps the dependency to an Option<T> by cloning the contents of the option.

impl<T: DependencyDefault> Dependency<T>

pub fn static_ref() -> &'static T

SAFETY

A DependencyDefault, once fetched, will last for the life of the process.

Holding this reference is not advised as it will not reflect further overrides of this dependency.

Trait Implementations

impl<T: DependencyDefault> AsRef<T> for Dependency<T>

fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.

impl<T: DependencyDefault> Borrow<T> for Dependency<T>

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<T> Default for Dependency<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T: DependencyDefault> Deref for Dependency<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.