Technical Articles

Functions that use references to base classes must be able to use objects of derived classes with out knowing it.

LSP Violation:

Class Product
{
Private :
String name;
String Author;
Public:
string getName();
setName(string name);
string getAuthor();
setAuthor(string author);
};
Class book : public product
{
};
Class movie:public product
{
};

If a author is queried with a product object which is actually a movie object ,the resulting behavior is not correct as the movie doesn’t have any author.

LSP:
Using derived classes should not end up in unexpected results when using derived classes.

The "Liskov's Substitution Principle" is just a way of ensuring that inheritance is used correctly.