What is metaclass in Ruby?
In addition to a class, every object in Ruby has a hidden metaclass. Metaclasses are singletons, which means that they belong to a single object. If you create multiple instances of a class, they will share the same class, but they will all have separate metaclasses.
In object-oriented programming, a metaclass is a class whose instances are classes. Just as an ordinary class defines the behavior of certain objects, a metaclass defines the behavior of certain classes and their instances. Not all object-oriented programming languages support metaclasses.
Metaclass is a profile class and a packable element that can be extended via one or more stereotypes. The metaclass can be extended by one or more stereotypes using a special type of association: extension. …
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How do you define an instance variable in Ruby?
An instance variable in ruby has a name that begins with the @ symbol, and its content is restricted to whatever the object itself refers to. Two separate objects, even though they belong to the same class, can have different values for their instance variables.
Primarily, metaclasses are defined like any other Python class, but they are classes that inherit from “type”.
Python classes can be created dynamically We have seen that everything in Python is an object, these objects are created by metaclasses. Every time we call class to create a class, there is a metaclass that does the magic of creating the class behind the scenes. This is because all of these objects are of type type .
Metaclasses extend the way to create a type beyond struct and class. For the sake of clarity, a class describes what an object looks like and is used at run time to instantiate objects. A metaclass describes what a class looks like and is used at compile time to create instances of classes.
A metaclass is essentially a class that Ruby creates and inserts into the inheritance hierarchy to contain class methods, so it doesn’t interfere with instances that are created from the class. Every object in Ruby has its own metaclass. It is somehow invisible to a developer, but it is there and you can use it very easily.
How do you define a class method interface in Ruby?
The class method interface we defined above is nothing more than an instance method defined in the metaclass for the object developer. A metaclass is essentially a class that Ruby creates and inserts into the inheritance hierarchy to contain class methods, so it doesn’t interfere with instances that are created from the class.
What does the self refer to in Ruby?
When the Ruby interpreter executes any code, it always keeps track of the eigenvalue for any given line. self always refers to some object, but that object can change depending on the code executed. For example, within a class definition, self refers to the class itself, which is an instance of the Class class.
How does the species method work in Ruby?
Ruby provides a syntax for directly accessing an object’s metaclass. By doing class << Person, we are setting self to the Person metaclass for the duration of the block. As a result, the species method is added to the Person metaclass, rather than the class itself.