Default method implementations in Rust - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a trait with a default method implementation.

Rust

trait Greet {
    fn say_hello(&self) {
        println!("[1]!");
    }
}

Drag options to blanks, or click blank then click option'

A"Hello"

B"Hi"

C"Hey"

D"Greetings"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the quotes around the string.

Using a method signature without a body.

The default method say_hello prints "Hello!" using println!.

2fill in blank

medium

Complete the code to override the default method in the struct implementation.

Rust

struct Person;

impl Greet for Person {
    fn say_hello(&self) {
        println!("[1]!");
    }
}

Drag options to blanks, or click blank then click option'

A"Welcome"

B"Good morning"

C"Hello"

D"Hi there"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the default greeting instead of overriding.

Missing the impl Greet for Person block.

The Person struct overrides the default say_hello method to print "Hi there!".

3fill in blank

hard

Fix the error in the trait method signature to allow a default implementation.

Rust

trait Farewell {
    fn say_goodbye(&self) -> [1] {
        println!("Goodbye!");
    }
}

Drag options to blanks, or click blank then click option'

Abool

Bi32

C()

DString

Attempts:

3 left

💡 Hint

Common Mistakes

Specifying a return type but not returning a value.

Using a non-unit return type without a return statement.

The method returns nothing, so the return type should be () (unit type) to allow a default implementation with println!.

4fill in blank

hard

Fill both blanks to define a trait with a default method that returns a string slice.

Rust

trait Describe {
    fn description(&self) -> [1] {
        [2]
    }
}

Drag options to blanks, or click blank then click option'

A&str

B"No description"

CString

D"Default description"

Attempts:

3 left

💡 Hint

Common Mistakes

Using String instead of &str as return type.

Returning a string literal without quotes.

The method returns a string slice &str and the default return value is "Default description".

5fill in blank

hard

Fill all three blanks to implement a trait with a default method that uses a generic type and returns a formatted string.

Rust

trait Info {
    fn info<T: ToString>(&self, value: T) -> [1] {
        format!("Value: [2]", value[3])
    }
}

Drag options to blanks, or click blank then click option'

AString

B{}

C.to_string()

D&str

Attempts:

3 left

💡 Hint

Common Mistakes

Using &str as return type but returning a formatted string.

Forgetting to convert the generic value to string.

Using incorrect format placeholders.

The method returns a String. The format string uses {} as placeholder, and value.to_string() converts the generic value to a string.