Using Cow in Rust for efficient memory utilization
Clone-on-write — or Cow for short — is a convenient wrapper that allows us to express the idea of optional ownership in Rust. In this article, we will learn what it exactly is, what problem it aims to solve, and how we can use it in our Rust code.
As a note, you should be comfortable with basic Rust to follow along with this tutorial, including control statements, structs, and enums.
Consider a case where you have a Vec of some elements. For the purposes of this example, consider that an Element has an ID that can uniquely identify it, and is large enough in size that duplicating it would require considerable memory.
In this case, we need to make sure the vector only has unique elements and does not contain any duplicates. To ensure this, we have a function that can filter the Vec. The code below demonstrates a simple way to implement this function:
As you can see, this simply keeps the IDs in a HashSet. When a new ID is encountered, it pushes the element into the Vec we return.
