We can return the function from other function as a value.
We can pass the function as a parameter to another function.We can store the function in a variable.A function can have its own properties and method.In JavaScript, functions are treated as first-class objects or first-class citizens, because they have the properties and methods the same as other objects.
Please read our previous article where we discussed Async Iterators and Generators in JavaScript. In this article, I am going to discuss the JavaScript function are First-class citizen with Examples.
Logtalk in javascript how to#
How to Delete or Remove a property using JavaScript Property Descriptors.How to Show or Hide a Property using Property Descriptors in JavaScript.How to Modify a Property using Data Descriptors in JavaScript.How to Create a new Property using Data Descriptors in JavaScript.Object Property Initializer Shorthand in JavaScript.How to Find the Length of a JavaScript Object.Traversing and Enumerate JavaScript Object Properties.Delete Property from a JavaScript Object.Add a new Property in JavaScript Objects.Accessing non-existent JavaScript Properties.JavaScript Object using Prototype Pattern.JavaScript Object Using Factory Pattern.JavaScript Object Using Object.create() Method.JavaScript Object Creation Using new Object() Method.Data Structures and Algorithms Tutorials.↩Ģ Using reexport/1-2 directives to implement inheritance is a know half-broken hack but that’s beside the point here. XSB) but comparing them is a topic for another post. A few Prolog modules systems are atom-based (e.g. Logtalk objects (which are capable of playing the role of both classes and prototypes) subsume Prolog modules and can do everything Prolog modules do and much more with elegance and aplomb.ġ Here we will only be discussing predicate-based Prolog modules. Note: the main motivation for this blog post is the well intended advice of some people in the community that Logtalk is handy when you need some OOP in your Prolog application. Likewise, if a module reexports other modules (or reexports predicates from other modules), an explicitly-qualified predicate call will work for any predicate in the reexport chain(s). When a prototype extends (or is derived from) other prototypes, message lookup will follow the derivation chain(s). Likewise, if a module doesn’t reexport other modules (or reexport predicates from other modules), implicit or explicitly, them an explicitly-qualified predicate call only checks the module itself. With a standalone prototype, message lookup only considers the prototype itself. MessagesĪlthough explicitly-qualified module predicate calls don’t perform the lookups associated with messages, they can still be interpreted as messages in a prototype system. With modules, we can use the reexport/1-2 directives to achieve similar functionality 2. Prototypes can also be created by expressing how they differ from other prototypes, know as their parent prototypes. For example, the following query creates a module named foo in most module systems (a notable exception being the ECLiPSe module system): Likewise, a Prolog module can be defined in a source file or dynamically created at runtime. Prototypes can be created ex-nihilo (i.e. It’s also a basic characteristic of Prolog module systems that each module have a unique identity (an atom). This is the most basic characteristic of an object in any OOP language. How is the OOP notion of a prototype materialized by a Prolog module? Let’s consider the defining characteristics of a prototype one-by-one: Identity It turns out that modules systems define a simple, limited, prototype-based OOP language. Self and JavaScript) instead of class-based. But OOP can also be declarative (as exemplified by Logtalk) and OOP languages can also be prototype-based (e.g. This often leads to the idea that Prolog modules are fundamentally distinct from objects. There is a partial but widespread view of not only OOP being a synonymous of imperative OOP but also OOP languages being a synonymous of class-based languages. But what modules are is a function of their characteristics, not a function of their design intentions 1. It is not the case that the creators of Prolog module systems intended to create an object-oriented extension to Prolog. From past experience, it will also annoy some Prolog practitioners.
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