The document discusses the Liskov Substitution Principle, a key concept within the SOLID principles of object-oriented design defined by Barbara Liskov in 1987. It states that objects of a superclass should be replaceable with objects of a subclass without affecting the correctness of the program. Additionally, it emphasizes that inheriting classes must maintain expected behavior when instances are substituted.

1. Liscov Substitution
Principle

2. S: Single Responsibility Principle
O: Open/Closed for Principle
L: Liskov Substitution Principle
I: Interface Segregation Principle
D: Dependency Inversion Principle
SOLID
Principles
2
OOD principles
Not design Patterns
By Bob Martin and
Michel Features

3. The principle, that Barbara
Liskov defined in 1987 in her
conference keynote named
"Data abstraction and
hierarchy".
Liscov Substitution
Principle
3

4. Liskov Substitution
Principle
4
Objects in a program
should be replaceable
with instances of their
subtypes without
altering the correctness
of that program.

5. Liskov Substitution
Principle
5
You should be able to
replace any instances of a
parent class with an
instance of one of its
children without creating
any unexpected or incorrect
behaviors.

6. Objects in a program should be replaceable with
instances of their subtypes without altering the
correctness of that program.
You should be able to replace any instances of a
parent class with an instance of one of its children
without creating any unexpected or incorrect
behaviors.
Liskov Substitution
Principle
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If S is a subtype
of T, then objects
of type T may be
replaced with
objects of type S

7. 7
If class Man is inherited
from class Human, then
objects of class Human
may be replaced with
objects of class Man.

8. 8
If class ……….. is inherited
from class ……………., then
objects of class ……... may
be replaced with objects of
class ………....

9. 9
…………...without altering the
correctness of that program.

10. Code Example
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11. 11
If class AdminUser is
inherited from class User,
then objects of class User
may be replaced with
objects of class AdminUser

12. Thank You
12