Struct Layer 

pub struct Layer { /* private fields */ }

A set of values addressed by dotted path.

Layer::new() is const, so this lives in a static — which is how #[dynamic_config] emits it. Every method takes &self, so a layer can be written to from anywhere without threading a handle around.

Example

use dynamic_config::Layer;

static OVERRIDES: Layer = Layer::new();

assert!(OVERRIDES.is_empty());

OVERRIDES.set("pool.max_size", 32u16).unwrap();
assert!(!OVERRIDES.is_empty());

OVERRIDES.clear();

Implementations

impl Layer

pub const fn new() -> Self

An empty layer.

pub fn set<T: Serialize>(&self, path: &str, value: T) -> Result<(), Error>

Sets path — dotted for nested fields, as in "pool.max_size".

Setting the same path again replaces it. The value is converted once, here, so a type that cannot be represented fails at the call site rather than at the next reload.

Errors

If path is empty or has a blank segment, or if value cannot be serialized.

pub fn set_text(&self, path: &str, text: &str) -> Result<(), Error>

Sets path from text, read the way an environment variable is.

"8080" becomes a number, "true" a boolean, "[a, b]" a list — the same loose reading the environment layer gets, so a value means the same thing whether it arrives as APP_DB_PORT=8080 or --set db.port=8080.

Errors

If path is empty or has a blank segment.

pub fn set_assignments<I, S>(&self, assignments: I) -> Result<(), Error>

where I: IntoIterator<Item = S>, S: AsRef<str>,

Sets every key=value in assignments.

The shape behind a --set key=value flag. A pair with no = is an error naming the offending argument rather than a silently ignored one.

Errors

If an assignment has no =, or its key is not a usable path.

pub fn bind_clap( &self, matches: &ArgMatches, bindings: &[(&str, &str)], ) -> Result<(), Error>

Available on crate feature clap only.

Copies clap arguments into this layer, by (argument id, key path).

Only arguments that came from the command line are taken. clap’s own default_value looks identical to a typed flag in ArgMatches, and letting a clap default outrank a configuration file would invert the whole precedence order — the file would be ignored in favour of a fallback nobody asked for.

Values are read the way environment variables are, so --port 8080 and APP_DB_PORT=8080 mean the same thing whatever type the argument was declared with.

flags.bind_clap(matches, &[("db-host", "host"), ("db-port", "port")])?;

Errors

If a key path is unusable, or an argument’s value is not valid UTF-8.

pub fn unset(&self, path: &str) -> bool

Removes path, reporting whether anything was there.

pub fn clear(&self)

Removes everything.

pub fn is_empty(&self) -> bool

Whether the layer would contribute anything.

Trait Implementations

impl Default for Layer

fn default() -> Layer

Returns the “default value” for a type.