Difference between object oriented and object based pdf
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- Object-based language
- Object-based language
- What is the 'Object'In Object-Oriented Programming?
- What is the difference between Object oriented programming and Object based programming?
In fact, one can probably use an arbitrary programming language and still write in an object- oriented style. However, object-oriented programming languages do exist with built-in constructs that support or enforce this style of programming. In its most basic form we may have a module of a program consisting of a number of static variables together with the set of procedures that are used to manipulate the variables.
A language like Fortran provides a fixed set of data types, such as integers and real numbers, each of which supports a number of operations addition, subtraction Languages like C and Pascal support the construction of programmer-defined types, one cannot define new type-specific operations. Object-oriented languages enable the programmer to create his or her own object types.
Objects can only be manipulated via their methods. Supporting this idea of object independence is a model for object communication which replaces the notion of operating on objects with that of passing messages to them. Every method invocation is seen as a message requesting the object to perform some action. The method is conceptually not performed by the caller, but by the object receiving the message. It follows, then, that the recipient of such a message is, in some sense, free to refuse the request, or choose from a variety of possible implementations of the method.
Classes of objects may not be disjoint. In fact, one may even have multiple implementations of a single type which only share their interface. By properly organizing such a type hierarchy, one may concentrate on the similarities between objects rather than on their differences. Fully object-oriented systems have a strong degree of homogeneity. This means that everything is an object. One does not distinguish between, say, programs and processes and files and objects — one only has objects, and objects are both active like processes and persistent like files.
Simply put, an actor is a cheap, persistent, message-passing process. The actor formalism as described in  is more rigorous, however this simple definition suffices for our purposes.
An actor must be inexpensive because we would like to be able to easily create and destroy them. If there is a one- to-one mapping between actors and objects, then it is clear that we may have many more actors than there are processes in a traditional multiprocessing environment, though at any one time only a few actors will actually be doing anything. The message-passing paradigm supports the notion of actors communicating with one another whether they are running on the same machine or not. At the same time, we note that there are several object-oriented languages and environments that do not support the notion of concurrently executing objects.
The main object-oriented concepts, then, are: 1. Data abstraction. Message-passing paradigm. Concurrency some systems. Nierstrasz 3 We shall elaborate on each of these concepts in turn, and attempt to explain their importance. By far the most important concept in the object-oriented approach is data abstraction.
By this we mean that we are interested in the behaviour of an object rather than in its representation. Furthermore, one may have many instances of an object type. The programmer is not restricted to a fixed set of types, but is free to add new types as required.
A module, however, only defines a single instance, whereas one may have many instances of a new type. In order to make use of an instance of that type, one only needs to know what the interface is, namely, the names of the methods, and the types of the input and output parameters. Naturally some specification of the semantics of the methods is also required.
The most immediate benefit of this approach is that the programmer is free to use higher levels of abstraction as appropriate. One is encouraged to decompose a programming problem into a collection of cooperating objects of varying levels of complexity.
The separation of interface and implementation of a new type means that types are, to some extent, representation-independent. This makes it easier to experiment with different implementa- tions of an object type, and increases the portability of software. It is, however, crucial to design an interface very carefully, since that is the part of an object type that remains stable across different implementations.
A language that allows programmers to define their own types is a natural candidate for strong typing. Type-checking is done as soon as possible, usually at compile-time. Sometimes one does not know at compile-time what kinds of objects will be manipulated, so one must do explicit type-checking at run-time; for example, a mailbox object may hold various types of mail objects. In an object-oriented language, one is typically allowed to use the same method names for a variety of different object types.
The type of the object to which such a method applies is, in a sense, an implicit argument to the method. Overloading allows for more readable code.
If used in an undisciplined fashion, however, overloading can have quite the opposite effect. Well-designed objects are typically applicable in a number of situations. There are several notions of independence displayed by objects. The most fundamental is that objects have control over their own state. Since this is not always guaranteed in languages that enable programmers to add new data types, it is worth emphasizing.
Clearly, if one has access to the internal representation of an object, then one loses the property that the implementation is independent of the interface. Objects also have control over their own existence. Once created, an object will continue to exist or persist even if its creator dies. One need not be concerned as a programmer with the location of an object in main memory or secondary memory.
Garbage collection, however, is compatible with this notion, since an object that is neither active nor accessible is effectively dead already. Another form of independence is the ability to add new object types at run-time. This is crucial if the object-oriented environment is also the development environment. If new types are to be added dynamically, then old objects must be capable to talking to instances of the newly-created types.
Compile-time type-checking is clearly not possible for those objects that will talk to objects of types that do not exist yet. Independence of objects is supported conceptually by using message-passing as a model for object communication. The only way an object can interact with the outside world is by sending messages.
Assuming all goes well and the message can actually be delivered, B is free to interpret the message as it pleases. It may choose amongst several ways of handling the request, it may delay responding, or it may decide that it does not wish to handle the request at all, and return an exception report. It is important to realize that message-passing is a model for object communication rather than an implementation requirement.
In fact, more than one object-oriented language translates message-passing into straightforward procedure calls. Message-passing may be synchronous or asynchronous. Basically, the difference is that with asynchronous message-passing the message is put on a queue, and the sender is immediately free to concentrate on another task though it usually just waits for a response. Nierstrasz 5 recipient prepares a response. The problem with asynchronous message-passing is that it is strictly speaking impossible to implement, since there is no bound on the size of the message queues.
The problem with synchronous message-passing is that it says nothing about the order of arrival of messages when multiple senders compete for a single recipient, and it limits the amount of concurrency by blocking the sender. Aynchronous message-passing is perhaps more consistent with the idea of object independence, but it is not a pre-requisite for an object-oriented system.
From the point of view of organizing software and reusability of code, the most important mecha- nism in an object-oriented language is the ability to specialize object types. A specialized type a subtype inherits the properties of its parent type, then possibly adds more properties.
A program source, for example, may be seen as a specialization, or refinement of a text object. An instance of a subtype responds to all the messages that the parent type understands. The reverse is not true. A subtype inherits the method interfaces of the parent type, but may add new methods that the parent cannot respond to. In addition, a subtype usually inherits the implementation of the parent by default, that is the set of instance variables that encode the state of a parent instance, and the implementations of all of the methods.
The subtype could add new instance variables and methods. A subtype may, however, have a different set of instance variables, and quite different imple- mentations of the inherited methods. For example, real numbers are a refinement of integers, but they are represented and implemented quite differently in a computer. The set of all object types forms a specialization hierarchy with the type object at the root.
With simple inheritance, this hierarchy is a tree. If multiple inheritance is supported, the hierarchy is, in general, a directed acyclic graph. This means that a subtype may have more than one parent type but no type can be its own ancestor!
The difference between a trait and a type if any is that a trait specifies an interface, but it need not define an implementation. One reason for this is that a trait may not be of interest as a type on its own. Such a trait might specify methods for setting the owner of the object, changing ownership, and determining access rights.
In a pure OO language, everything is an object, and every action is taken through them Smalltalk, for instance. Get 5 credit points for each correct answer. Internally function is nothing its … Everything is an object in Smalltalk. You will get to see examples that falls into each of the classifications. All operations are performed by sending messages to objects: Let us take an instance of adding two numbers. These benefits include: As in other Pure Object Oriented Language, an object is always an instance of a class. In partial Object Oriented Language, data members and methods can be given outside classes as well.
What is the 'Object'In Object-Oriented Programming?
The term " object-based language " may be used in a technical sense to describe any programming language that uses the idea of encapsulating state and operations inside "objects". Object-based languages need not support inheritance or subtyping , but those that do are also said to be "object-oriented". Object-based languages that do not support inheritance or subtyping are usually not considered to be true object-oriented languages. NET , C , and Fortran These languages all support the definition of an object as a data structure, but lack polymorphism and inheritance.
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Object oriented programming provides data hiding so it is more secure. In Object oriented programming, there are three Overloading in the form of function overloading The focus of procedural programming is to break down a Procedural Language vs Object Oriented Language Summary: Difference Between Procedural Language and Object Oriented Language is that in a procedural language, the programmer writes instructions that tell the computer what to accomplish and how to do it. Your data is stored in properties, your logic in methods. NET, C.
What is the difference between Object oriented programming and Object based programming?
In this page, we will learn about the basics of OOPs. Object-Oriented Programming is a paradigm that provides many concepts, such as inheritance , data binding , polymorphism , etc. Simula is considered the first object-oriented programming language. The programming paradigm where everything is represented as an object is known as a truly object-oriented programming language. The main aim of object-oriented programming is to implement real-world entities, for example, object, classes, abstraction, inheritance, polymorphism, etc. Object means a real-world entity such as a pen, chair, table, computer, watch, etc. Object-Oriented Programming is a methodology or paradigm to design a program using classes and objects.
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