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Rust Ownership Rules
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Flashcards
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In Rust, variables are immutable by default.
True. In Rust, variables are indeed immutable by default. This means that once a variable's value is set, it cannot be changed unless explicitly marked as mutable with the 'mut' keyword.
A variable automatically implements the 'Copy' trait if all of its parts implement the 'Copy' trait.
True. Composite types (like structs or tuples) in Rust will automatically implement the 'Copy' trait if all of their fields implement the 'Copy' trait.
In Rust, borrowing a value temporarily transfers ownership of that value.
False. When you borrow a value in Rust, you are only creating a reference to that value without transferring ownership. Ownership remains with the original variable.
Rust's tuples are subject to the same ownership rules as other types.
True. Tuples in Rust are composite types and they follow the same ownership rules as other types including struct and enums.
Once ownership of a value is transferred, the original owner can no longer use it.
True. When ownership is transferred in Rust, the original variable cannot be used to access the value anymore as it has been 'moved'.
It is possible to have both mutable and immutable references to a value in the same scope.
False. Rust's borrowing rules prevent you from having mutable and immutable references to the same value in the same scope to avoid potential data races.
You can have multiple mutable references to a piece of data in the same scope.
False. Rust's ownership rules enforce that there can only be one mutable reference to a particular piece of data in a particular scope, to prevent data races.
In Rust, reference counting can be used to enable multiple owners of the same data.
True. Reference counting, using types like 'Rc<T>' or 'Arc<T>', allows multiple variables to own the same data, with the count ensuring that the data remains valid while there is at least one owner.
Implementing the Copy trait for a type allows for implicit data copying without moving ownership.
True. By implementing the Copy trait for a type, you're telling Rust that values of that type can be duplicated implicitly, without requiring a 'move'.
Rust's 'Drop' trait is called when an object goes out of scope, to release its owned resources.
True. The 'Drop' trait in Rust is used to specify the cleanup code that runs when an instance of that type is about to be deallocated or 'dropped'.
All types that implement the 'Copy' trait also implement the 'Clone' trait.
True. In Rust, any type that implements the 'Copy' trait must also implement the 'Clone' trait, because 'Copy' is a subset of 'Clone' functionality.
A function in Rust takes ownership of all parameters passed to it by default.
True. Unless parameters are explicitly borrowed (using references), functions in Rust will take ownership of the parameters passed to them.
In Rust, you can circumvent the borrow checker by using unsafe code.
True. Rust's 'unsafe' keyword allows you to write code that can potentially violate ownership rules, bypassing the borrow checker's safety guarantees.
The 'clone' method can be used to create a deep copy, enabling both variables to own the data.
True. The 'clone' method is used to create a deep copy of the data. Both the original and the cloned instance have their own separate ownership of the data.
In Rust, 'Box<T>' is used to allocate values on the stack.
False. 'Box<T>' is a smart pointer that allocates values on the heap, not the stack. It provides a way to store data outside of the stack's strict ownership rules.
You can have as many immutable references to a variable as you want in the same scope.
True. Rust's ownership rules allow for multiple immutable references in the same scope because no data race can occur if the data is not being mutated.
Shadowing in Rust creates a new variable, allowing the mutated value to be assigned to the same name.
True. Shadowing in Rust is a feature that allows you to declare a new variable with the same name as a previous variable, effectively creating a new binding.
It is acceptable for multiple threads to mutate the same data in Rust without synchronization mechanisms in place.
False. When dealing with concurrency, Rust's ownership rules still apply and prevent data races; manual synchronization mechanisms (like mutexes) are required for safe multi-threaded mutable data access.
Values can be returned from functions without transferring ownership if they are borrowed.
True. By returning a reference from a function instead of the value itself, you do not transfer ownership, but you must ensure that the referenced data lives long enough.
The 'borrow checker' is a tool that ensures programs conform to Rust's ownership rules at runtime.
False. The borrow checker is a compile-time feature of Rust that ensures ownership and borrowing rules are followed, preventing unsafe code from being compiled.
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