OOP – init Method

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Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. What does __init__ do?

A Deletes the object

B Initializes a new object automatically

2. When does __init__ run?

A When an object is created

B When an object is deleted

3. What must be the first parameter of __init__?

A self

B this

4. class Dog:\n def __init__(self, name):\n self.name = name\nDog('Rex') what is self.name?

A 'Rex'

B 'name'

5. Do you pass 'self' when creating an object?

A Yes

B No Python passes it automatically

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1class Dog: def __init__(name): self.name = name		AOutput: 3
2class Dog: def __init__(self, name): self.name = name Dog()		BValid: __init__ with parameter
3class Dog: def __init__(self, name): self.name = name		COutput: Rex
4d = Dog('Rex') print(d.name)		DError: Missing required arg 'name'
5class Dog: def __init__(self,n): self.name=n d=Dog('Rex') print(d.name)		EError: First param must be 'self'
6class Point: def __init__(self,x,y): self.x=x self.y=y p=Point(3,4) print(p.x)		FOk: Access attribute after creation

Definitions

__init__

Fill in the Blanks

Complete each line of code by filling in the missing parts.

class Dog: def ________(self, name): self.name = name

class Dog: def ________(self): self.name = name

class Dog: def ________(self, name): ____.name = name

dog = Dog(_____) print(dog.name)

class Person: def __init__(self, name, age): self.___ = age

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A class Dog:

B def __init__(name):

C self.name = name

Question 2

A class Dog:

B def _init_(self, name):

C self.name = name

Question 3

A class Dog:

B def __init__(self, name):

C name = name

Question 4

A class Dog:

B def __init__(self, name):

C self.name = name

E dog = Dog()

F print(dog.name)

Question 5

A class Dog:

B def __init__(self, name):

C self.name = name

E dog = Dog('Rex', self)

Answer Key

OOP – __init__ Method

Section A: Quick Questions

B — Initializes a new object automatically

A — When an object is created

A — self

A — 'Rex'

B — No Python passes it automatically

Section B: Match the Pairs

class Dog: def __init__(name): self.name = name → Error: First param must be 'self'

class Dog: def __init__(self, name): self.name = name Dog() → Error: Missing required arg 'name'

class Dog: def __init__(self, name): self.name = name → Valid: __init__ with parameter

d = Dog('Rex') print(d.name) → Ok: Access attribute after creation

class Dog: def __init__(self,n): self.name=n d=Dog('Rex') print(d.name) → Output: Rex

class Point: def __init__(self,x,y): self.x=x self.y=y p=Point(3,4) print(p.x) → Output: 3

Section C: Definitions

__init__ — Constructor method that runs automatically when an object is created.~~self

Section D: Fill in the Blanks

class Dog:
    def __init__(self, name):
        self.name = name

class Dog:
    def __init__(self):
        self.name = name

class Dog:
    def __init__(self, name):
        self.name = name

dog = Dog('Rex')
print(dog.name)

class Person:
    def __init__(self, name, age):
        self.age = age

Section E: Spot the Error

B — Missing self as the first parameter

B — Need DOUBLE underscores: __init__ not _init_

C — Must use self.name to save on the object. name alone is just a local variable.

E — __init__ expects a name argument Dog() without it causes TypeError

E — Don't pass self Python does it automatically