Key Points to Ownership and Borrow Checking in Rust < Part 2 >

Rust is a modern systems programming language that provides powerful memory management features to ensure memory safety without compromising performance. In this blog post, we will explore two key concepts in Rust: ownership and borrow checking. Understanding these concepts is crucial for writing safe and efficient Rust code.

Borrow Checking

Borrow checking is a mechanism in Rust that regulates how variables are accessed. It ensures that there are no data races or dangling references, leading to safer code. Here are some important points to know about borrow checking:

1. Means of accessing a variable: In Rust, variables can be accessed by borrowing them. Borrowing allows multiple references to access a value without taking ownership.

2. Rebinding with the same variable name until borrowed is legit: Rust allows rebinding a variable with the same name until it is borrowed. This enables flexible and intuitive code organization.

3. Only one mutable borrow can exist per object: Rust enforces a strict rule that only one mutable borrow (read-write access) can exist for a particular object at a time. This rule prevents data races and ensures thread safety.

Ownership

Ownership is a fundamental concept in Rust that governs how memory is managed. It prevents common memory-related bugs such as use-after-free and double-free. Here's what you need to know about ownership in Rust:

1. Two ways to shift ownership: Ownership can be transferred in Rust through assignment or by passing values as arguments or return values to functions.

2. Avoiding ownership issues: To avoid unnecessary ownership transfers, Rust provides the following alternatives:

   • Use references when full ownership is not required:

     • &T denotes a read-only reference.

     • &mut T denotes a mutable reference for read-write access.

   • Duplicate values:

     • Cloning: Create a new object by cloning parts of an existing object using the .clone() method. Cloning can be slow and expensive.

     • Copying: Certain types that implement the Copy trait can be copied efficiently. Copying is fast and cheap.

     • Derive traits automatically: Use #[derive(Copy, Clone, Debug)] to add the required traits automatically. However, custom implementations are also possible.

   • Wrap data with special types: Rust provides special types that can affect runtime performance but offer specific benefits:

     • Rc (Reference Count): A reference-counted smart pointer from the standard library (std::rc::Rc). Use it when mutation is not required. For mutation, use Rc<RefCell<T>>.

     • Arc (Atomic Reference Count): Similar to Rc, but with thread-safe atomic operations.

   • Reduce the lifetime of objects: By limiting the scope or lifetime of objects, you can ensure that they are dropped and their resources are freed in a timely manner.

Other Key Points

1. Primitive types have the Copy trait, allowing them to be efficiently copied.

2. Non-primitive types have the Move trait, which transfers ownership instead of copying.

3. Custom destructors can be implemented using the Drop trait. It is used in conjunction with the unsafe keyword.

4. Inner mutability can be achieved using RefCell to mutate an immutable item. This allows mutable access within an immutable reference.

<Part 1 >

https://utsavchindalia.hashnode.dev/key-points-to-get-started-with-rust-part-1