More Object Oriented

Some time back I went back over a textbook I had from my Object Oriented Analysis and Design class. The book was authored by Grady Booch. The title of the book was Object-Oriented Analysis and Design with Applications. I have covered some ideas from this book in previous blog posts. This time I want to finish up some topics I read in the book.

A very popular term within the OO world is polymorphism. This means one name with many implementations. In other words, you have multiple related classes with the same function name. Then depending on the object upon which you are calling the method, you will get the right implementation executed.

There is another scenario where you have the same function name, but multiple implementations. This is where you have multiple functions within the same class that have the same name. However they are differentiated by the number and/or types of parameters that are passed in to the function. The official name for this behavior is overloading.

Another key idea in OO is that of aggregation. This is a big word to say that one object has another object or item as part of it. A synonym for this idea is containment. There are some lesser used OO topics that Booch mentions. One of them is that of a meta class, where the instances of the class are classes themselves. That does not sound familiar from my experience.

Some techniques for performing object oriented analysis and design are use cases and CRC cards. I have only hear about but never participated in CRC card analysis. Apparently you get together in a room and write down things on physical cards. I have done a lot of use case work in the past. However these days we skip that during out analysis phase. So do our requirements people.

Finally I read up on parametrized classes. These are classes whose behavior depends on parameters passed to the class. In C++, this idea is implemented as templates. I do have a little experience with templates in general. However I believe I want to beef up that experience.