Self is an object-oriented programming language designed for writing efficient, dynamic, and self-modifying software. It was developed in the 1980s at Xerox PARC as an experimental research project in the field of programming language design. The language was later used to develop several real-world applications, including the Self web browser and the Morphic user interface framework. In this guide, we will introduce the Self programming language, explain how to write programs in Self with an example, and discuss the best applications for it.
What is Self Language:
Self is a dynamically-typed, prototype-based programming language that is similar to Smalltalk. It is designed to be simple, expressive, and reflective, allowing developers to easily create and modify objects at runtime. One of the key features of Self is that it is a self-hosting language, meaning that the Self virtual machine and compiler are written in Self itself. This makes it easy to modify the language and experiment with new features.
How to write programs in Self:
Self programs are written using objects and messages. An object is a collection of data and behavior that can respond to messages. Messages are sent to objects to ask them to perform some action or return some value. The syntax of Self is very simple and easy to learn. Here is an example program that creates a point object and displays its x and y coordinates:
```
| point |
point := ( | x y |).
point x: 10.
point y: 20.
"Display the point's x and y coordinates"
point x display.
point y display.
```
In this example, we create a point object that has two slots, x and y, using a vertical bar notation. We then set the x and y slots to the values 10 and 20, respectively, using the message passing syntax. Finally, we display the values of the x and y slots using the display message.
Best Applications of Self:
Self is primarily used for developing high-performance software systems that require dynamic and reflective behavior. It is particularly well-suited for developing user interfaces, web browsers, and virtual machines. The Self web browser is a good example of the power of the language, as it was able to achieve high performance and dynamic behavior that was not possible with other programming languages at the time. The Morphic user interface framework is another example of the power of Self, as it allows developers to create dynamic and interactive graphical user interfaces with ease.
Conclusion:
Self is a powerful and expressive programming language that is well-suited for developing dynamic and reflective software systems. Its simplicity, flexibility, and reflective capabilities make it a popular choice for developing user interfaces, web browsers, and virtual machines. With this guide, you now have a basic understanding of how to write programs in Self and what the best applications for it are. We encourage you to explore the language further and experiment with its features to see what you can create with it.