All that is required to establish this behavior-sharing between objects is the delegation pointer. In prototype-based languages that use delegation, the language runtime is capable of dispatching the correct method or finding the right piece of data simply by following a series of delegation pointers (from object to its prototype) until a match is found. The former is supported through some form of object literal, declarations where objects can be defined at runtime through special syntax such as // bar.] = foo const bar = Object. There are two methods of constructing new objects: ex nihilo ("from nothing") object creation or through cloning an existing object. The prototype property is called prototype in Self and JavaScript, or proto in Io. Objects inherit directly from other objects through a prototype property. In prototype-based languages there are no explicit classes. The Omega language discussed in Prototype-Based Programming is an example of such a system, though according to Omega's website even Omega is not exclusively static, but rather its "compiler may choose to use static binding where this is possible and may improve the efficiency of a program." Systems based on statically typed languages are technically feasible, however. Many prototype-based systems encourage the alteration of prototypes during run-time, whereas only very few class-based object-oriented systems (such as the dynamic object-oriented system, Common Lisp, Dylan, Objective-C, Perl, Python, Ruby, or Smalltalk) allow classes to be altered during the execution of a program.Īlmost all prototype-based systems are based on interpreted and dynamically typed languages. What could be more object oriented than that? Īdvocates of prototype-based programming argue that it encourages the programmer to focus on the behavior of some set of examples and only later worry about classifying these objects into archetypal objects that are later used in a fashion similar to classes. We don't need classes to make lots of similar objects… Objects inherit from objects. These can then act as prototypes for even newer objects. Objects are mutable in JavaScript, so we can augment the new instances, giving them new fields and methods. You make prototype objects, and then … make new instances. Prototypal inheritance in JavaScript is described by Douglas Crockford as:
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