In Ruby, what is self? The special variable self in Ruby points to the object that “has” the code is executed at the moment. Self is used all over Ruby: for example, as a variant of local variables, method names and definitions, and constant lookup. In principle, self appears obvious enough; yet in practice, unexpected circumstances may occur that are difficult to resolve because of this so I wrote this article.
Remember, in Ruby, classes, and modules are interchangeable. This action isn’t any different from the instance method behavior we examined in the previous example.
When writing a class, it’s important for the instance variables to be defined within the body of that same class rather than outside of its definition file. self has no meaning if there are no instance variables attached to it – which means they’re not part of any object at all! This might seem like an unusual thing since one would think self should always refer back to itself regardless of what’s going on around it. However, this isn’t true at all when using classes or modules as objects themselves instead of simply defining them. When you use def, self actually becomes equivalent with Object. But by default, every method will have access to other methods and variables inside their own bodies, self-included. So self will refer to the object that’s executing the code, not necessarily what it’s attached to if you’re using class or module objects directly instead of their files!
self is a special variable in Ruby programming language and has different meanings depending on context. For example, self inside method refers back to an instance where the method.
self is also available in blocks and procs. self inside a block will point to the receiver of that block, self outside any definition means current Object (universal) . self comes into play when you are explicitly defining methods within an iterator or block context. This topic can be confusing for newbies so we decided to write a guide about self in ruby today. As always our goal is to make your learning process easier because knowledge should be clear like water.
When compared to “normal” instance or class methods, self-mixed techniques function similarly. This makes sense. Otherwise, the mixin wouldn’t be able to communicate with the class you blended it into. Let’s say you want define method which modifies a given object but still needs access to self. You would use self-mixed technique.
Mixin methods can be defined either within a class or module definition or outside of one using the extended self syntax. A mixin method is available on every instance that includes it through inheritance. The term “instance” here refers to any object who inherits self from its parent (superclass). Any time you dynamically generate an anonymous subclass with include, including new up an anonymous module that mixes in another module, you are creating multiple instances of your classes and modules. So each added mixin becomes available as self inside their associated instances’ context.
self has some very special applications when used via self-defined techniques like mentioned above but’s more than meets the eye!