Trait Layer 

pub trait Layer: for<'de> Deserialize<'de> {
    // Required methods
    fn empty() -> Self;
    fn default_values() -> Self;
    fn from_env() -> Result<Self, Error>;
    fn with_fallback(self, fallback: Self) -> Self;
    fn is_empty(&self) -> bool;
    fn is_complete(&self) -> bool;
}

A configuration layer: all fields are optional. Can be directly deserialized via serde.

Required Methods

fn empty() -> Self

Returns Self where all fields/values are None or empty.

fn default_values() -> Self

Returns an object containing all default values (i.e. set via #[config(default = ...)] when deriving Config) with all remaining values/fields set to None/being empty.

fn from_env() -> Result<Self, Error>

Loads values from environment variables. This is only relevant for fields annotated with #[config(env = "...")]: all fields not annotated env will be None.

If the env variable corresponding to a field is not set, that field is None. If it is set and non-empty, but it failed to deserialize into the target type, an error is returned. If set to an empty string and if it fails to deserialize, it’s treated as not set.

fn with_fallback(self, fallback: Self) -> Self

Combines two layers. self has a higher priority; missing values in self are filled with values in fallback, if they exist. The semantics of this method is basically like in Option::or.

fn is_empty(&self) -> bool

Returns true if all values are unspecified/None.

fn is_complete(&self) -> bool

Returns true if all required (non-optional) values in this configuration are set. If this returns true, Config::from_layer will not return an error.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors