Instance methods in Ruby - Step-by-Step Execution

Concept Flow - Instance methods

Create Object

↓

Call Instance Method

↓

Method Uses Object's Data

↓

Return or Print Result

↓

End

An instance method is called on an object and can use that object's data to perform actions or return values.

Execution Sample

Ruby

class Dog
  def bark
    "Woof!"
  end
end

dog = Dog.new
puts dog.bark

This code creates a Dog object and calls its instance method bark, which returns 'Woof!'.

Execution Table

Step	Action	Object State	Method Called	Output
1	Define class Dog with method bark	No objects yet	None	None
2	Create dog object with Dog.new	dog: instance of Dog	None	None
3	Call dog.bark	dog: instance of Dog	bark	"Woof!"
4	Print output of dog.bark	dog: instance of Dog	None	Woof!
5	End of program	dog: instance of Dog	None	None

💡 Program ends after printing 'Woof!' from dog.bark method

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
dog	undefined	Dog instance created	Dog instance unchanged	Dog instance unchanged

Key Moments - 2 Insights

Why do we call bark on dog and not on Dog class?

Instance methods belong to objects, not the class itself. The execution_table row 3 shows dog.bark calls bark on the dog object.

What does the bark method return?

The bark method returns the string "Woof!" as shown in execution_table row 3 and printed in row 4.

Visual Quiz - 3 Questions

Look at the execution table, what is the output when dog.bark is called at step 3?

A dog object

B nil

C "Woof!"

D Error

💡 Hint

Check the Output column at step 3 in the execution_table

At which step is the dog object created?

A Step 2

B Step 3

C Step 1

D Step 4

💡 Hint

Look at the Action and Object State columns in the execution_table

If we add a method that uses dog’s data, when would that method be called?

A After calling dog.bark

B Only on the dog object after it is created

C Before creating the dog object

D On the Dog class itself

💡 Hint

Instance methods work on objects, see concept_flow and execution_table steps

Concept Snapshot

Instance methods belong to objects.
Call them on an object, not the class.
They can use the object's data.
Syntax: def method_name inside class.
Call: object.method_name
Returns value or performs action.

Full Transcript

This example shows how instance methods work in Ruby. First, a class Dog is defined with an instance method bark that returns "Woof!". Then, a dog object is created using Dog.new. The instance method bark is called on this dog object, returning the string "Woof!" which is then printed. Instance methods belong to objects, so you call them on an instance like dog, not on the class Dog itself. The execution table traces each step: defining the class, creating the object, calling the method, printing the output, and ending the program. The variable tracker shows the dog variable starting undefined, then holding the Dog instance after creation, and unchanged after method calls. Key moments clarify why methods are called on objects and what the method returns. The visual quiz tests understanding of these steps and concepts. This helps beginners see how instance methods run step-by-step.