The OOP is a programming paradigm using objects and their interactions to design applications and computer programs. It is based on several techniques, including inheritance, modularity, polymorphism, and encapsulation. Currently there are many programming languages \u200b\u200bthat support object orientation.
Objects are entities that combine state , behavior and Identity: The
- state is composed of data, will be one or more attributes which are to be assigned specific values \u200b\u200b(data).
- The behavior is defined by the procedures or methods that can operate the object, ie, what operations can be done with it.
- The identity is a property of an object that distinguishes it from the rest, in other words, is the identifier (ID concept similar to a variable or constant ).
oriented programming object expresses a program as a set of these objects, which collaborate with each other to perform tasks. This allows the programs and modules easier to write, maintain and reuse.
Thus, an object contains all the information you can define and identify it to other objects belonging to other classes and even objects in front of the same class, can have distinct values \u200b\u200bin its attributes. In turn, object interaction mechanisms have called methods that promote communication between them. This communication helps to turn the state change in the objects themselves. This feature has to treat them as indivisible units, where no separate or be separated from the state and behavior.
methods (behavior) and attributes (state) are closely related to the overall property. This property features a class requires methods to treat the attributes with which account. The programmer should think alike on both concepts, without separating or give greater weight to any of them, it could produce the wrong habit of creating wrapper classes for information on one side and classes with methods that handle the first on the other. This will be conducting a camouflaged structured programming in a programming language object-oriented.
OOP features
- Abstraction: Every object in the model system serves as an "agent" abstract work can inform and change its status, and "communicating "with other objects in the system without revealing how these features are implemented. Processes, functions or methods can also be abstracted as they are, a variety of techniques are required to extend an abstraction. Encapsulation
- : It means bringing all the elements that can considered to belong to the same entity, the same level of abstraction. This may increase the cohesion of system components. Some authors confuse this concept with the principle of concealment, mainly because they often used together.
- concealment principle: each object is isolated from the outside, is a natural module, and each type of object exposes an interface to other objects that specifies how they interact with the objects of the class. The insulation protects the properties of an object against its modification by a person not entitled to access them, only the object's own internal methods can access their state. This ensures that other objects can not change the internal state of an object in unexpected ways, eliminating unexpected side effects and interactions. Some languages \u200b\u200brelax this by allowing direct access to internal data of the object in a controlled manner and limit the degree of abstraction. The entire application is reduced to an addition or object puzzles. Polymorphism
- : different behaviors associated with different objects can share the same name, to call them by that name is used for the object's behavior is being used. Or put another way, the references and collections of objects can contain objects of different types, and invocation of a reference behavior will produce the correct behavior for the actual type of object referenced. When this happens in "runtime", the latter feature is called belated allocation or dynamic allocation . Some languages \u200b\u200bprovide more static media (in "compile time") of polymorphism, such as templates and operator overloading of C + +. Heritage
- : classes are not isolated, but interrelated, forming a hierarchy of classification. Objects inherit the properties and behavior of all kinds to which they belong. Organizes and facilitates inheritance polymorphism and encapsulation allowing objects to be defined and created as specialized types of existing objects. They can share (and extend) their behavior without having to reimplement their behavior. This is usually done routinely grouping objects and classes are in trees or trellises reflecting common behavior. When an object inherits from more than one class is said to be multiple inheritance, this feature is not supported by some languages \u200b\u200b(like Java).
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