# Advanced Traits (Rust)

> Associated types vs generics, GATs, trait objects, dyn keyword, object safety, vtables

- 22 interview questions
- Senior
- [Interview Questions: Rust](https://sharpskill.dev/en/technologies/rust/interview-questions.md)

## 1. What is the main difference between an associated type and a generic parameter in a trait?

**Answer**

An associated type allows only one trait implementation per type, while a generic parameter allows multiple implementations. With an associated type, the type is determined by the implementation itself, which simplifies type inference and avoids specifying the type at each use.

## 2. Which keyword is used to create a trait object in Rust?

**Answer**

The dyn keyword is used to create a trait object in Rust. It indicates that method dispatch will happen dynamically at runtime via a vtable, as opposed to static dispatch with generics which is resolved at compile time.

## 3. What is a vtable in the context of trait objects?

**Answer**

A vtable (virtual table) is a table of pointers to the trait method implementations for a concrete type. It is used for dynamic dispatch of trait objects, allowing the correct method to be called at runtime without knowing the concrete type at compile time.

## 19 more questions available

- What condition must a trait meet to be object-safe?
- Why is the Clone trait not object-safe?

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## Other Rust interview topics

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