Structs

Question 1

What is a struct?

Answer 1

A type this is composed of other types.

Question 2

How are structs different then tuples?

Answer 2

Each value in a struct is named.

Question 3

What keyword is used to create a struct?

Answer 3

struct.

Question 4

What is the syntax for creating a struct?

Answer 4

struct struct_name {
field_name: type,
}

Question 5

How do we create an instance of a struct?

Answer 5

State the name of the struct and then add curly brackets containing key: value pairs, where the keys are the names of the fields and the values are the data we want to store in those fields.

Question 6

How do we access a specific value from a struct?

Answer 6

dot notation. e.g. user.email

Question 7

What is the field init short hand

Answer 7

Pattern that allows for only writing the variable name when assigning it to a struct field if they share the same name. email: email can be written as just email.

Question 8

What is the struct update syntax?

Answer 8

Any fields not explicitly set can be set from another struct instance with ..  e.g. 
let user2 = User {
    email
    foo: String::from("bar"),
    ..user1
};

Question 9

What is a tuple struct

Answer 9

A tuple that is named. Individual fields are not named.

Question 10

When are tuple structs useful?

Answer 10

When you want to give the whole tuple a name and make the tuple be a different type from other tuples, and naming each field as in a regular struct would be verbose or redundant.

Question 11

What are unit-like structs

Answer 11

structs without any fields.

Question 12

When are unit-like structs useful?

Answer 12

Situations in which you need to implement a trait on some type but don’t have any data that you want to store in the type itself.

Question 13

How are methods different than functions?

Answer 13

They are declared within the context of a struct, enum, or trait object and their first parameter is always self.

Question 14

How do we define a function within the context of a struct?

Answer 14

We start an impl (implementation) block. e.g. 
impl Rectangle {
    fn area(&self) -> u32 {
        self.width * self.height
    }
}

Question 15

What is the first parameter to a method?

Answer 15

self.

Question 16

Describe how automatic referencing and dereferencing works?

Answer 16

When you call a method with object.something(), Rust automatically adds in &, &mut, or * so object matches the signature of the method.

Question 17

What is an associated function?

Answer 17

A function that does not take self as the first parameter. They often associated with a struct and used as a Constructor.

Question 18

What is the syntax of an associated function

Answer 18

:: with struct name. e.g. let sq = Rectangle::square(3);

Question 19

How many impl blocks is a struct allowed to have?

Answer 19

Multiple.