In this page , I will explain the limit of the object-oriented that is about to be impossible to realize in the object-oriented.
After all, when we design in the object-oriented , we should know the limit.
The way of searching the limit of the object-oriented and the design that is impossible to realize in the object-oriented is studying about the aspect-oriented1,2.
If you study the aspect-oriented , I think that you can know the limit of the object-oriented.
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Note.
1: In this page , I will not explain about the aspect-oriented.
If you want to know the aspect-oriented and aspect-oriented programming, please read 4. Reference or search by the Google.
2: Of course , I think that there are other ways.
If you search by other ways, it is possible to find other limit and weakpoint of the object-oriented.
I will explain about the limit of the object-oriented that I obtained by studying the aspect-oriented.
For example , It is assumed there is a case that you want to program a content of a method of a class.
Then , there are a lot of cases that you must program inessential processes.
For example , Logging , Access Control and so on 1. These are necessary to be written at various places.
And , the programming is troublesome , and if we once wrote , the modification is difficult.
Thus, the processing not brought together in one place or the function is called a "Crosscutting Element".
And , if there are crosscutting elements (it is often) , I think that you should think you can not design the better design when you design in the object-oriented.
The impossible one is impossible.
You should think the cost of the programming and modification is very much.
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Note.
1: Sorry, I understand only these.
By the way , about the logging and access control , I also have the experience.
There is the logging as the example that we can not design in the object-oriented . I will explain about this.
In the object-oriented , you can design the class like the Figure 1.
Figure 1 - The example of the Logger class 1
But , the problem is the case that we use this class.
For example , if there are 1,000 places that you want logging , you must write the process used the Logger class at 1,000 places.
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Note.
1: This class is a class that I designed.
If in java language , I think that you should not create the logger class , but use java.util.logging package.
I will explain about the access control too.
The access control is not the visibility of the class diagram (+:public , -:private and so on) .
This means the role based access control. For example , directors can read and write a data , but employees can only read a data.
In object-oriented ( and in not object-oriented too ) , we can create the method that checks the access authority for the data to check the group name of the user.
But , the problem is a number of the method that checks the authority.
For example , there are 50 datas. And there are the getter and setter methods of those. And if the all getter and setter method is needed the access control , you must program checking process at 100 ( 50 * 2 ) places.
The access control is needed at not only the getter and setter method but the other methods.
It is very serious.
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