What is the real significance(use) of polymorphism

Question

I am new to OOP. Though I understand what polymorphism is, but I can\'t get the real use of it. I can have functions with different name. Why should I try to implement polym

Answer 1

In a strictly typed language, polymorphism is important in order to have a list/collection/array of objects of different types. This is because lists/arrays are themselves typed to contain only objects of the correct type.

Imagine for example we have the following:

// the following is pseudocode M'kay:
class apple;
class banana;
class kitchenKnife;

apple foo;
banana bar;
kitchenKnife bat;

apple *shoppingList = [foo, bar, bat]; // this is illegal because bar and bat is
                                       // not of type apple.

To solve this:

class groceries;
class apple inherits groceries;
class banana inherits groceries;
class kitchenKnife inherits groceries;

apple foo;
banana bar;
kitchenKnife bat;

groceries *shoppingList = [foo, bar, bat]; // this is OK

Also it makes processing the list of items more straightforward. Say for example all groceries implements the method price(), processing this is easy:

int total = 0;
foreach (item in shoppingList) {
    total += item.price();
}

These two features are the core of what polymorphism does.