Enum Setting 

pub enum Setting<T> {
    Unset,
    Set {
        value: T,
        origin: Option<OriginId>,
    },
}

An atomic merge boundary in the configuration tree.

A set setting also records where its value came from if it has been set. Because parsing logic does not understand origins, they are attached separately.

Variants

Unset

Set

Fields

value: T

origin: Option<OriginId>

Implementations

impl<T> Setting<T>

pub fn value(value: T) -> Self

Create a set setting whose origin is not (yet) known.

pub fn value_from(value: T, origin: OriginId) -> Self

Create a set setting originating from origin.

pub fn is_unset(&self) -> bool

Return true if this setting is unset.

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

Return the value in this setting, if it is set.

pub fn default_to(&mut self, value: impl FnOnce() -> T)

Set this setting to its built-in default if no document supplied a value. The default is only produced when it is needed, so a setting a document supplied never pays for computing one it will not use.

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

Consume this setting, returning the value in it, if it is set.

pub fn require(self, path: &ConfigPath) -> Result<T, ConfigError>

Consume this setting, returning the value in it. If no value is set, returns an error naming the setting.

Trait Implementations

impl<T: Clone> Clone for Setting<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for Setting<T>

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

Formats the value using the given formatter.

impl<T> Default for Setting<T>

fn default() -> Self

Returns the “default value” for a type.

impl<'de, T> Deserialize<'de> for Setting<T>

where T: Deserialize<'de>,

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<T> Eq for Setting<T>

where T: Eq,

impl<T> Merge for Setting<T>

A setting is a leaf node, so we don’t need to bother too much about merging.

fn merge( &mut self, incoming: Self, context: &mut MergeContext<'_>, ) -> Result<(), ConfigError>

impl<T> PartialEq for Setting<T>

where T: PartialEq,

Two settings are equal when they carry equal values.

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<T> PartialValue for Setting<T>

where T: PartialValue,

fn attribute(&mut self, origin: OriginId)

A setting records its own origin, and visits its nested values.

fn apply_defaults(&mut self)

A setting holds no default of its own, since the field it belongs to supplies that; it only lets nested values be defaulted. Note that if this setting itself should have been defaulted, that should have happened at the parent level.

fn resolve(self, path: &mut ConfigPath) -> Result<Self::Resolved, ConfigError>

A setting resolves to whatever its value is, and is missing if no document and no default supplied one.

type Resolved = <T as PartialValue>::Resolved

What this becomes once the configuration is complete.

impl<T> Serialize for Setting<T>

where T: Serialize,

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.