# Vessel
`vessel::Vessel` is a simple, immutable value bag for Rust – inspired by Go's `context.Context`, but focused solely on storing and propagating context in a simple manner.
## ✨ Features
- Immutable: setting a value returns a new `Vessel`.
- Ordered: uses a `BTreeMap` internally for deterministic iteration.
- Ergonomic: fluent API with zero dependencies (aside from the standard library).
- Useful for threading context-like metadata (e.g., request IDs, tenant info) through application layers.
## 📦 Example
```rust
use vessel::Vessel;
let vessel = Vessel::new();
let vessel = vessel.with_value("request_id", "abc-123");
assert_eq!(vessel.get_value("request_id"), Some(&"abc-123".to_string()));
````
## 📚 API
```rust
pub fn new() -> Self;
pub fn with_value(&self, key: &str, value: &str) -> Self;
pub fn get_value(&self, key: &str) -> Option<&String>;
pub fn get_values(&self) -> &BTreeMap<String, String>;
```
* `with_value`: Adds a key-value pair to the vessel, returning a new instance.
* `get_value`: Retrieves a value for a given key.
* `get_values`: Returns all key-value pairs.
## 🧪 Tests
Run tests with:
```bash
cargo test
```
## 📜 License
MIT