Purposes

CowArc can be useful for decreasing memory allocations by sharing immutable memory.

It saves some RAM by sharing immutable values between CowArc clones. Memory allocates only in case of changing value.

CowArc can be usefull for creating builders.

Examples

```rust let source = CowArc::new(vec![1, 2, 3]);

// Still shared memory let mut changed = cloned.clone(); assert!(std::ptr::eq(source.deref(), changed.deref()) == true); assert!(changed.eq(&vec![1, 2, 3]));

// New memory allocation changed.set_val(vec![1, 2, 3, 4]); assert!(std::ptr::eq(source.deref(), changed.deref()) == false); assert!(changed.eq(&vec![1, 2, 3, 4])); ```

```rust let source = CowArc::new(vec![1, 2, 3]);

// Still shared memory let mut updated = source.clone(); assert!(std::ptr::eq(source.deref(), updated.deref()) == true); assert!(changed.eq(&vec![1, 2, 3]));

// New memory allocation updated.update_val(|val|{ val.push(4); }); assert!(std::ptr::eq(source.deref(), updated.deref()) == false); assert!(updated.eq(&vec![1, 2, 3, 4])); ```