Object oriented programming 1

Question 1

What are attributes?

Answer 1

Attributes are specific properties of an object.

"Matz".length
# ==> 4
Matz is an object
.lenght is a method
4 is an attribute

Question 2

What is a class?

Answer 2

A class is a way to organize and produce objects with similar attributes and methods.

Basically a blueprint.

Question 3

How do you write a class?

Answer 3

class ClassName
   # some code
end

You use CamelCase for the class name

Question 4

What is the initialize method?

Answer 4

The initialize method is used to boost up the class, it gives us attributes that we can start up with.
It will run every time we create the class.

Question 5

What is an instance variable?

Answer 5

An instance variable makes the variable available in other parts of the application

Question 6

What is scope of a variable?

Answer 6

The scope of a variable is where the variable is accessible for the rest of the program. Some variables are not accessible to other parts of the program.

Question 7

What are global variables?

Answer 7

Variables that are available everywhere

Question 8

What are local variables?

Answer 8

Variables that are only available inside certain methods.

Question 9

How do you write instance variables?

Answer 9

you write them with a @

@variable_name

Question 10

How do you write class variables?

Answer 10

You write them with two @@

@@variable_nameHow do yo wr

Question 11

How do you write global variables?

Answer 11

1) You just define the variable outside the method or class.

2) If you are writing the global variable from inside a method or a class just write $ before the variable.

Question 12

How should you create variables?

Answer 12

You should only create them with a limited scope so that they can only be changed from a few places.

Question 13

What is inheritance?

Answer 13

inheritance is the process by which one class takes on the attributes and methods of another.

Question 14

What is the inheritance syntax?

Answer 14

you use the < symbol to show the inheritance.

class DerivedClass < BaseClass
  # Some stuff!
end

This means that DerivedClass inherits from BaseClass.

Question 15

What is override?

Answer 15

If you want a class to not to take the attributes of the baseclass

Question 16

What is the super keyword?

Answer 16

The super keyword is used when you want to accesses the attributes or the methods of a superclass

Question 17

How do you set up a class in ruby?

Answer 17

class SomeName
end

Question 18

What is inheritance?

Answer 18

Inheritance means that a class has access to all methods and behaviors of another class. You use the < to show the inheritance.

Question 19

What can you store in a class in ruby?

Answer 19

You can store both methods and data in a class.

Question 20

What is the getter method in a class?

Answer 20

The getter method allows you to retrieve data or values from a class.

Question 21

What is the setter method in a class?

Answer 21

The setter method allows you to set values in a class.

Question 22

What is the attr_accessor?

Answer 22

The attr_accsessor stands for attribute accessor and is used instead of the getter and setter methods.

Question 23

What does instantiation mean?

Answer 23

When you create a class it’s like creating a blueprint, to instantiate a class means to build the house from a blueprint. To actually use the class to create.

Question 24

What is an initializer method?

Answer 24

An initializer method is a method that will run every time you create a new instance of a class.

Question 25

What are optional values?

Answer 25

When you are not sure that you want to pass on a value as an argument, you can assign the value to be optional. It will only be assigned if you give an argument.

You write value = something if you want it to be optional

Question 26

Why do we use inheritance in ruby?

Answer 26

We use inheritance because repeating code is a bad practice.

Question 27

What is service-based architecture?

Answer 27

It is when you use third party services instead of creating your own.

Question 28

What is a public method?

Answer 28

A public method is a method inside a class that can be used by anyone working with that perticular class. 
These are really important if you are giving access to these methods via an API.

Question 29

What are private methods?

Answer 29

Private methods are methods that can only be called from whitin the class and not by an external service or user.

Question 30

How do you make a method private?

Answer 30

You add the keyword private to a section of your class, and all methods that are added below that keyword will be private.

Ex
class Example

def method_1
some_code
end

private

def method_2
some_code
end

end

Question 31

What is polymorphism in ruby?

Answer 31

Polymorphism is when the behavior from the parent class is overridden by the child class.

Question 32

How do you use Polymorphism?

Answer 32

You use it by defining a new class with the same method name, the method of the child class will be run instead of the method from the parent class.

Question 33

What is the super keyword and when do you use it?

Answer 33

The super keyword allows us to use both methods from parent and child classes instead of polymorphism.

You use it by adding the keyword inside the method you want the parent class to override

Question 34

What is the single responsibility principle?

Answer 34

It means that each class and module in the application should only focus on a single task.