Struct SourceChain 

pub struct SourceChain<'src>(/* private fields */);

An ordered chain of ConfigSources. Assembly walks the chain in order; within one source its env var is checked before its TOML value; the first source to answer either wins for that field. Build one with SourceChain::new and SourceChain::push, then pass it to EnvConfig::assemble.

Implementations

impl<'src> SourceChain<'src>

pub fn new() -> Self

Creates an empty chain.

pub fn push(self, source: &'src dyn ConfigSource) -> Self

Appends source to the end of the chain (lowest priority so far).

pub fn iter(&self) -> impl Iterator<Item = &'src dyn ConfigSource> + '_

Iterates the chain in priority order (first pushed, checked first).

pub fn toml_value(&self, key: &str) -> Option<&Value>

The first source in the chain that has a TOML value for key, if any. A default_fn uses this to derive its field from a sibling field’s raw value (for example deriving auth_url from api_url) without duplicating the chain-walk resolve_field already does.

pub fn env_name(&self) -> Option<&str>

The environment name of the first source in the chain that has one (see ConfigSource::env_name), if any. A default_fn uses this to derive its field from the environment’s own identity (for example account.{name}.example.com).

Trait Implementations

impl Debug for SourceChain<'_>

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

Formats the value using the given formatter.

impl<'src> Default for SourceChain<'src>

fn default() -> SourceChain<'src>

Returns the “default value” for a type.