Objective-J
Objective-J
Paradigm Multi-paradigm: reflective, object-oriented, functional, imperative, scripting
Developer Cappuccino Core Developers and community.
First appeared 2008
Typing discipline dynamic, weak, duck
License LGPL
Website cappuccino-project.org
Influenced by
Objective-C, JavaScript

Objective-J is a programming language developed as part of the Cappuccino web development framework. Its syntax is nearly identical to the Objective-C syntax and it shares with JavaScript the same relationship that Objective-C has with the C programming language: that of being a strict, but small, superset; adding traditional inheritance and Smalltalk/Objective-C style dynamic dispatch. Pure JavaScript, being a prototype-based language, already has a notion of object orientation and inheritance, but Objective-J adds the use of class-based programming to JavaScript.

Programs written in Objective-J need to be preprocessed before being run by a web browser's JavaScript virtual machine. This step can occur in the web browser at runtime or by a compiler which translates Objective-J programs into pure JavaScript code. The Objective-J compiler is written in JavaScript; consequently, deploying Objective-J programs does not require a web browser plug-in. Objective-J can be compiled and run on Node.js.

Applications

The first widely known use of Objective-J was in the Cappuccino-based web application 280 Slides, which was developed by 280 North itself. Even though Objective-J can be used (and has been designed) independently from the Cappuccino framework, Objective-J has primarily been invented to support web development in Cappuccino.

Applications designed using the Cappuccino Framework[1]

Syntax

Objective-J is a superset of JavaScript, which means that any valid JavaScript code is also valid Objective-J code.

The following example shows the definition and implementation in Objective-J of a class named Address; this class extends the root object CPObject, which plays a role similar to the Objective-C's NSObject. This example differs from traditional Objective-C in that the root object reflects the underlying Cappuccino framework as opposed to Cocoa, Objective-J does not use pointers and, as such, type definitions do not contain asterisk characters. Instance variables are always defined in the @implementation.

@implementation Address : CPObject
{
  CPString name;
  CPString city;
}

- (id)initWithName:(CPString)aName city:(CPString)aCity
{
  self = [super init];

  name = aName;
  city = aCity;

  return self;
}

- (void)setName:(CPString)aName
{
  name = aName;
}

- (CPString)name
{
  return name;
}

+ (id)newAddressWithName:(CPString)aName city:(CPString)aCity
{
  return [[self alloc] initWithName:aName city:aCity];
}

@end

As with Objective-C, class method definitions and instance method definitions start with '+' (plus) and '-' (dash), respectively.

Memory management

Objective-C uses ARC (Automatic Reference Counting) for deallocating unused objects. In Objective-J, objects are automatically deallocated by JavaScript's Garbage Collector.

See also

References

External links


  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.


Objective-J
 



 
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