Modeling Polymorphism and Its Various Forms
Definition
Polymorphism
Polymorphism means “many forms” - the ability of objects to take on different forms depending on context.
- The same method name or operator can behave differently based on the object or arguments involved.
- Promotes flexibility, reusability, and cleaner code in OOP.
Think of polymorphism as a single interface with multiple behaviours.
Confusing polymorphism with inheritance: inheritance is the mechanism, polymorphism is the behaviour.
Forms of Polymorphism
- Compile-time (Static):
- Decided at compile time.
- Achieved by method overloading or operator overloading (Python supports operator overloading but not true method overloading).
- Runtime (Dynamic):
- Decided at runtime.
- Achieved by method overriding in subclasses.
- Static = overloading, decided early
- Dynamic = overriding, decided late.
Saying Python supports method overloading in the same way as Java: it does not.
Method Overloading (Static Polymorphism)
- Definition Reminder: Same method name, different parameter lists (different number or type of parameters).
- Return type alone is NOT enough to distinguish overloaded methods in Java, the compiler needs different parameters.
- Compile-time resolution: The method to execute is chosen at compile-time based on the arguments passed.
- Default parameters in Python: Since Python doesn’t support true overloading, default parameters and *args / **kwargs are often used to mimic it.
Python:
class MathOps:
def add(self, a, b=0):
return a + bJava:
class MathOps {
int add(int a, int b) {
return a + b;
}
double add(double a, double b) {
return a + b;
}
}- In Java: Stress that signature = method name + parameter list.
- In Python: Show how flexible arguments simulate overloading since Python only keeps the last defined method.
