Struct Var 

pub(super) struct Var<'env, 'lookup, T, C = fn(&'static str, T) -> Result<T>> {
    lookup: &'lookup (dyn Fn(&str) -> Option<String> + 'env),
    read_file: &'lookup (dyn Fn(&Path) -> Result<String> + 'env),
    key: &'static str,
    check: C,
    aliases: Vec<&'static str>,
    file_source: Option<FileSource>,
    value: PhantomData<fn(T) -> T>,
}

Parses the first present key and validates its value in check order.

Checks may transform values and capture other settings. They receive the supplying key, including aliases. Defaults use the primary key and pass through the same checks. Missing optional values bypass parsing and checks.

Fields

lookup: &'lookup (dyn Fn(&str) -> Option<String> + 'env)

read_file: &'lookup (dyn Fn(&Path) -> Result<String> + 'env)

key: &'static str

check: C

aliases: Vec<&'static str>

file_source: Option<FileSource>

value: PhantomData<fn(T) -> T>

Implementations

impl<'env, 'lookup, T, C> Var<'env, 'lookup, T, C>

where T: EnvParse, C: Fn(&'static str, T) -> Result<T>,

pub(super) fn check( self, check: impl Fn(&'static str, T) -> Result<T>, ) -> Var<'env, 'lookup, T, impl Fn(&'static str, T) -> Result<T>>

Appends a check that runs only after all preceding checks succeed.

pub(super) fn alias(self, alias: &'static str) -> Self

pub(super) fn or_load_from_file(self, alias: &'static str) -> Self

pub(super) fn exclusive_file(self, alias: &'static str) -> Self

Loads the file only when no direct source is configured.

Reading a direct source together with this file source returns an anyhow::Error without reading the file or disclosing the direct value.

pub(super) fn required(self) -> Result<T>

Returns the parsed and checked value of the first present key.

Errors

Returns anyhow::Error when every key is absent or parsing or a check fails.

pub(super) fn default(self, default: T) -> Result<T>

Uses the typed default only when every key is absent.

Errors

Returns anyhow::Error when parsing or a check fails, including checks of the default value.

pub(super) fn optional(self) -> Result<Option<T>>

Returns None only when every key is absent.

Errors

Returns anyhow::Error when parsing or a check of a present value fails.

fn load(&self) -> Result<Option<EnvValue>>

fn parse(&self, value: EnvValue) -> Result<T>