compile-time and runtime

Compile-Time

• Happens before the program runs (during code compilation).

• Errors like syntax errors, type mismatches, or method overloading are checked here.

• Polymorphism Example → Method Overloading
  ↳ Same method name, different parameters
  ↳ Resolved at compile time

Example:

Copyclass Test {
    void show(int a) {}
    void show(String b) {}
}

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⚡ Runtime

• Happens while the program is running.

• Errors like null pointer, array out of bounds, etc., occur here.

• Polymorphism Example → Method Overriding
  ↳ Subclass method replaces parent method
  ↳ Resolved at runtime using object type

Example:

Copyclass A {
    void show() { System.out.println("A"); }
}
class B extends A {
    void show() { System.out.println("B"); }
}
A obj = new B();
obj.show(); // Output: B

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what about self. is this run or compile?

Arre nice question 👌

🧩 self in Python → runtime concept

• self refers to the current instance of the class.

• It is not a keyword like this in Java/C++ → just a naming convention.

• Gets passed automatically when calling instance methods.

• Exists only when the object is created at runtime, not during compilation.

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💡 So?

• self is resolved at runtime

• Python is dynamically typed → no compile-time type checks like Java or C++

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Quick example:

Copyclass Test:
    def show(self):
        print("Address of object:", self)

obj = Test()
obj.show()

• self here → refers to obj, and obj is created at runtime