2. Objects

2. Objects
	Chapter 1. Object Oriented Programming

2.1. Object

An entity able to save a state (information) and which offers a number of operations (behaviours) to either examine or affect this state.

2.2. Object Oriented Model

It is one where the components of the modelled system are represented by a number of objects. These objects usually correspond to real life entities, such as a share, an invoice, or a customer. Information (states) and operations (behaviours) to each object.

Figure 1.2. The outside world view of an object

Table 1.1. Invoice Object

Invoice Object State	Invoice Object Operations
Company to be invoiced	Bill the customer
Value	Add Taxes
Taxes Deductions	Change Address
etc.	etc.

2.3. What is important?

Information hiding: The only part of an object accessible from the outside should be its operations, its inside should be hidden from the outside world.
Encapsulation:Encapsulating related variables and methods into a neat software bundle is a simple yet powerful idea that provides two primary benefits to software developers.
Advantages:
- Information hiding
- Modularity

2.4. Communication

Message Passing:More pure;
Method calling: More efficient .

2.5. Audio

Audio in Portuguese


1. Semantic Gap		3. Classes and Instances