Comparison With Class-based Models
With class-based languages, the structure of objects is specified in programmer-defined types called classes. While classes define the type of data and functionality that objects will have, instances are "usable" objects based on the patterns of a particular class. In this model, classes act as collections of behavior (methods) and structure that are the same for all instances, whereas instances carry the objects' data. The role distinction is thus primarily based on a distinction between structure and behavior on the one hand, and state on the other.
Advocates of prototype-based programming often argue that class-based languages encourage a model of development that focuses first on the taxonomy and relationships between classes. In contrast, prototype-based programming is seen as encouraging 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. As such, 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, Smalltalk, Objective-C, Python, Perl, or Ruby) allow classes to be altered during the execution of a program.
Almost all prototype-based systems are based on interpreted and dynamically typed languages. Systems based on statically typed languages are technically feasible, however. 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."
See section "Criticism" for further comparison.
Read more about this topic: Prototype-based Programming
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