In chapter ten, we looked at data and how to identify classes that were needed from Use Cases. In Chapter 11, we look at Information Exchange through Events. An Event is not the data that has been changed, but rather that information has been exchanged between elements. An Event occurs when information that is exchanged:…
Data transformation is often simple like splitting a full name into the first and last, or vice versa. However, sometimes it is more complicated, much more complicated. I once wrote a data converter which had to convert data stored in a file with the size of data store being a certain number of bytes into…
Previously we’ve seen how variables are passed by value. While this works well in many cases, it means that the variable has to be duplicated when it is passed to the function. For large, and/or complicated, variables – like when we start using objects, this can take precious time and resources. However, C++ offers us…
Many times, two or more analysis classes are related to one another in some fashion or another. In UML this is called associations. With Object Oriented code, we often ask if two classes are related or associated through a is-a or has-a type relationship. For example: a car (and object) has a(n) engine (an other…
Operations define the behaviors of the object. While there are lots of different behaviors, they can often be broken down into four main categories. Those that manipulate data often have a set in their function name. Such as setPassword(). Those that check the state of an object usually return a boolean value, and use the…
Attributes help describe a class. They are what help us differentiate from one object and another. Attributes should be relevant to the system that you are building. So two similar objects might have very different attributes based upon how it is used. Consider a College Student Athlete. The data needed for your sports team is…
Some things are easy to identify as a class. For example, if you look around the room, you can find lots of physical objects which can be made into classes. However, in a software environment, this may not always be as easy to identify. So look at the following questions to start to identify what…
Variables must be declared before they can be used in C++. This is why a lot of developers follow the best practice of defining the variables at the top of a function. Variable Scope By default variables can be used in the function that they are created. This is their scope, is is often referred…
