Ruby
- Ruby is an interpreted, high-level, general-purpose programming language.
- Ruby is dynamically typed and uses garbage collection.
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It supports multiple programming paradigms, including procedural, object-oriented, and functional programming.
- The term pure object-oriented programming implies that all of the data types in the language are objects and all operations on those objects can be invoked by message passing.
- Multiple variables referencing the same object is called aliasing
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dup
- a = (b = 1 + 2) + 3
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nil
- Class names, module names, and constants should start with an uppercase letter.
- Class variables start with two “at” signs (@@).
- Local variables, method parameters, and method names should all start with a lowercase letter or with an underscore (_).
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Global variables are prefixed with a dollar sign ($), while instance variables begin with a single “at” sign.
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Unstructured programming Complex code: Difficult to read and write. • Poor evolvability. • Poor maintainability. • Poor reusability.
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Structured programming Allowed (some) abstraction from the underlying machine. • Poor evolvability. • Poor maintainability. • Poor reusability.
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Procedural programming Allows functional decomposition of a problem. • Top-town design and stepwise refinement allow the problem to be broken down into (manageable) subproblems. • Modular composition is made possible as solutions to subproblems can be coded into units of functionality (procedures and functions) or components
- Object-oriented programming Encapsulation + Polymorphism + Inheritance • Provides linguistic mechanisms to support functional decomposition along the notion of class. • Allows us to view computation as a set of collaborating objects. • Classes allow us to hide implementation details beneath interfaces.