Java vs Self: What are the differences?

# Key Differences between Java and Self

Java and Self are both object-oriented programming languages, but they have several key differences that set them apart. Below are some of the most significant distinctions between the two languages.

1. **Prototype-based vs. Class-based Inheritance**: One of the primary differences between Java and Self is their approach to inheritance. Java follows a class-based inheritance model, where objects are created based on predefined classes and inherit properties and methods from their parent classes. In contrast, Self implements a prototype-based inheritance model, where objects inherit directly from other objects without the use of classes.

2. **Static vs. Dynamic Typing**: In Java, variables are statically typed, meaning that their data types are explicitly declared at compile time. This allows for type checking and helps catch errors early in the development process. On the other hand, Self is dynamically typed, where variables are not assigned a specific data type until runtime. This flexibility can lead to more concise code but may increase the likelihood of runtime errors.

3. **Reflective vs. Non-reflective**: Self is known for its high level of reflexivity, allowing objects to inspect and manipulate their own structure and behavior at runtime. This feature enables powerful introspection and code modification capabilities. In contrast, Java has limited reflection capabilities, with strict restrictions on what can be inspected and modified at runtime, primarily for security reasons.

4. **Garbage Collection**: Java employs automatic garbage collection, where the runtime environment manages memory deallocation for objects no longer in use. This helps prevent memory leaks and simplifies memory management for developers. Self, on the other hand, relies on manual memory management, requiring programmers to explicitly release memory allocated to objects when they are no longer needed.

5. **Encapsulation and Accessibility**: Java enforces strict access control mechanisms using keywords like private, protected, and public to manage the visibility of class members. This promotes encapsulation and helps maintain code integrity by preventing unintended access to object state. In Self, there are no built-in access modifiers, and all object members are inherently accessible from anywhere in the program, promoting a more flexible but potentially less secure coding style.

6. **Compilation and Execution**: Java code is typically compiled into bytecode, which is then executed by the Java Virtual Machine (JVM). This provides platform independence and allows Java programs to run on any system with a compatible JVM. Self, on the other hand, uses a just-in-time (JIT) compiler to translate the code into machine language at runtime, offering potentially faster execution but lacking the portability of Java bytecode.

In Summary, Java and Self differ in their approach to inheritance, typing, reflection, memory management, access control, and compilation, making them suited for different programming paradigms and use cases.