ConfigSource

hexcfg::ports::source

Trait ConfigSource 

Source 
pub trait ConfigSource: Send + Sync {
    // Required methods
    fn name(&self) -> &str;
    fn priority(&self) -> u8;
    fn get(&self, key: &ConfigKey) -> Result<Option<ConfigValue>>;
    fn all_keys(&self) -> Result<Vec<ConfigKey>>;
    fn reload(&mut self) -> Result<()>;

    // Provided method
    fn get_str(&self, key: &str) -> Result<Option<ConfigValue>> { ... }
}
Expand description

A trait for configuration sources.

This trait defines the interface that all configuration sources must implement. It provides methods for retrieving configuration values, listing all available keys, and reloading the source if supported.

§Thread Safety

Implementations must be Send + Sync to allow for use in multi-threaded contexts.

§Priority

Each source has a priority value (0-255) that determines the order in which sources are queried. Higher priority values take precedence over lower ones. The typical priority values are:

  • 3 (highest): Command-line arguments
  • 2: Environment variables
  • 1 (lowest): Configuration files and remote services

§Examples

use hexcfg::ports::ConfigSource;
use hexcfg::domain::{ConfigKey, ConfigValue, Result};

struct MySource;

impl ConfigSource for MySource {
    fn name(&self) -> &str {
        "my-source"
    }

    fn priority(&self) -> u8 {
        1
    }

    fn get(&self, key: &ConfigKey) -> Result<Option<ConfigValue>> {
        // Implementation here
        Ok(None)
    }

    fn all_keys(&self) -> Result<Vec<ConfigKey>> {
        Ok(vec![])
    }

    fn reload(&mut self) -> Result<()> {
        Ok(())
    }
}

Required Methods§

Source

fn name(&self) -> &str

Returns the name of this configuration source.

This name is used for logging, error messages, and debugging. It should be a short, descriptive identifier like “env”, “yaml-file”, “etcd”, etc.

§Examples
let source = MySource;
assert_eq!(source.name(), "my-source");
Source

fn priority(&self) -> u8

Returns the priority of this configuration source.

Priority determines the order in which sources are queried. Higher values take precedence over lower values. When multiple sources provide a value for the same key, the value from the source with the highest priority is used.

§Priority Guidelines
  • 3: Command-line arguments (highest priority)
  • 2: Environment variables
  • 1: Files and remote services (lowest priority)
§Examples
let source = MySource;
assert_eq!(source.priority(), 2);
Source

fn get(&self, key: &ConfigKey) -> Result<Option<ConfigValue>>

Retrieves a configuration value for the given key.

Returns Ok(Some(value)) if the key exists in this source, Ok(None) if the key does not exist, or Err if an error occurred while retrieving the value.

§Arguments
  • key - The configuration key to retrieve
§Returns
  • Ok(Some(ConfigValue)) - The value was found
  • Ok(None) - The key does not exist in this source
  • Err(ConfigError) - An error occurred
§Examples
let source = MySource;
let key = ConfigKey::from("app.name");
let value = source.get(&key).unwrap();
assert!(value.is_some());
Source

fn all_keys(&self) -> Result<Vec<ConfigKey>>

Returns all configuration keys available in this source.

This method is useful for discovering available configuration options, debugging, and validation.

§Returns
  • Ok(Vec<ConfigKey>) - A list of all available keys
  • Err(ConfigError) - An error occurred while retrieving keys
§Examples
let source = MySource;
let keys = source.all_keys().unwrap();
assert_eq!(keys.len(), 2);
Source

fn reload(&mut self) -> Result<()>

Reloads the configuration from the source.

This method allows sources to refresh their data from the underlying storage. For sources that don’t support reloading (like command-line arguments), this can be a no-op that returns Ok(()).

§Returns
  • Ok(()) - The source was successfully reloaded (or reloading is not applicable)
  • Err(ConfigError) - An error occurred while reloading
§Examples
let mut source = MySource;
source.reload().unwrap();

Provided Methods§

Source

fn get_str(&self, key: &str) -> Result<Option<ConfigValue>>

Retrieves a configuration value for the given key string.

This is a convenience method that automatically converts a string slice into a ConfigKey. It’s equivalent to calling get(&ConfigKey::from(key)).

§Arguments
  • key - The configuration key as a string slice
§Returns
  • Ok(Some(ConfigValue)) - The value was found
  • Ok(None) - The key does not exist in this source
  • Err(ConfigError) - An error occurred
§Examples
let source = MySource;
// No need to create a ConfigKey manually!
let value = source.get_str("app.name").unwrap();
assert!(value.is_some());

Implementors§