Instance methods in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an instance method in Ruby?

An instance method is a function defined inside a class that can be called on objects (instances) created from that class. It operates on the data contained in the specific object.

beginner

How do you define an instance method in a Ruby class?

You define an instance method inside a class using the <code>def</code> keyword followed by the method name. For example:<br><pre>class Dog
  def bark
    puts "Woof!"
  end
end</pre>

beginner

How do you call an instance method in Ruby?

First, create an object (instance) of the class, then call the method on that object using dot notation. For example:<br>

dog = Dog.new
dog.bark  # Calls the bark method

intermediate

What is the role of self inside an instance method?

Inside an instance method, self refers to the current object (instance) on which the method was called. It helps access or modify the object's data.

intermediate

Can instance methods access instance variables? How?

Yes. Instance methods can read or change instance variables using the @ symbol. For example:<br>

def name
  @name
end

accesses the @name variable of the object.

How do you define an instance method in Ruby?

A Using <code>class method_name</code>

B Using <code>def self.method_name</code> inside a class

C Using <code>function method_name()</code>

D Using <code>def method_name</code> inside a class

Instance methods are defined with def method_name inside a class. Option B defines a class method.

What does self refer to inside an instance method?

A The current object (instance)

B A global variable

C The class itself

D The method name

self inside an instance method refers to the object that called the method.

How do you call an instance method named greet on an object person?

A <code>person.greet</code>

B <code>call greet on person</code>

C <code>Person.greet</code>

D <code>greet.person</code>

You call instance methods on objects using dot notation: person.greet.

Can instance methods access instance variables?

A No, only class methods can

B Only if they are global variables

C Yes, using the <code>@</code> symbol

D Only if passed as arguments

Instance methods can access instance variables using the @ symbol, like @name.

Which of these is an instance method definition?

A def self.run

B def run

C def Class.run

D def @run

Instance methods are defined with def method_name. Option A defines a class method.

Explain what an instance method is and how it is used in Ruby.

Think about how methods belong to objects.

Describe how self works inside an instance method and why it is useful.

Consider what 'self' means when you call a method on an object.