What is an Eigenclass?

What is an Eigenclass?

Noun. eigenclass (plural eigenclasses) (object-oriented programming) A hidden class associated with each specific instance of another class.

What is an eigen class in Rails?

The eigenclass is an unnamed instance of the class Class attached to an object and which instance methods are used as singleton methods of the defined object.

What is singleton Ruby?

Singleton is a creational design pattern, which ensures that only one object of its kind exists and provides a single point of access to it for any other code. Singleton has almost the same pros and cons as global variables. Although they’re super-handy, they break the modularity of your code.

What is Metaclass in Ruby?

When you declare a singleton method on an object, Ruby automatically creates a class to hold just that method. This class is called the ‘metaclass’ of the object. Whenever you send a message to the object, it first looks to see whether the method exists in its metaclass.

What is Eigenclass Ruby?

The Eigenclass When you create an instance of a class, Ruby creates a hidden class, basically a copy of the original class, but that is owned exclusively by this instance. This is the Eigenclass. If you modify the Eigenclass of your first instance, it won’t change anything for another instance.

What is monkey patching in Ruby?

In Ruby, a Monkey Patch (MP) is referred to as a dynamic modification to a class and by a dynamic modification to a class means to add new or overwrite existing methods at runtime. This ability is provided by ruby to give more flexibility to the coders.

What is the point of metaclasses?

The main purpose of a metaclass is to change the class automatically, when it’s created. You usually do this for APIs, where you want to create classes matching the current context.

What are Ruby callbacks?

Technically, a “callback” is just executable code that is passed as an argument to a function. Ruby describes their callbacks as hooks into object life cycles, where a “hook” is a way to execute code before, after, or instead of existing code.

What is metaprogramming example?

Metaprogramming is writing programs that write programs . For example, when a User model is defined in Rails with email as an attribute, a method called find_by_email will be generated.

Why is it called a monkey patch?

Etymology. The term monkey patch seems to have come from an earlier term, guerrilla patch, which referred to changing code sneakily – and possibly incompatibly with other such patches – at runtime. The word guerrilla, nearly homophonous with gorilla, became monkey, possibly to make the patch sound less intimidating.

What is a metaclass in Smalltalk?

The name of the metaclass is the Smalltalk expression that, when evaluated, results in the metaclass object. Thus evaluating Car class results in the metaclass object for Car whose name is Car class (one can confirm this by evaluating Car class name which returns the name of the metaclass of Car .)

What is a lambda in Ruby?

In Ruby, a lambda is an object similar to a proc. Unlike a proc, a lambda requires a specific number of arguments passed to it, and it return s to its calling method rather than returning immediately.

What is hook in Ruby?

Ruby Hook Methods are called in reaction to something you do. They are usually used to extend the working of methods at run time. These methods are not defined by default, but a programmer can define them according to imply them on any object or class or module and they will come into picture when certain events occur.