Analysis of Structures - Baustatik-Info-Server

2.14. OOP WITH CLASSES Page 412.13.3 Close a FileAfter the usage of a file, the file should be closed.f.close()...... example ......f.open("log.txt","a")f.write("Write a little log line\n")f.close()2.14 OOP with ClassesPython is an object orientated programing language 13 . Everything within Python is implemented as anobject, even a simple integer number. So what is the concept of a class? A class or an object combinesdata, called attributes, with functions, called methods. This can be described by so called UML 14An instance of a class, that is the realization of the class in memory, is created simply by assigning theclass’s name followed by the constructors parameter list to a symbolic name, which than is the pointer orthe reference to this instance. Within the class the self pointer to the actual instance is called self. Toaccess member attributes or methods of a class the dot notation is used, i.e. ..We can remove an instance of a class by calling the del operator (del example). The referencesto an instance are handled by the python runtime system. If an instance has lost all it’s references, theinstance is removed from the memory. 152.14.1 Some UML DiagramsUML structure diagrams of the emphasize the things that must be present in the system being modeled.Since structure diagrams represent the structure they are used extensively in documenting the architectureof software systems. In our description of the examples we want to implement we use the ClassDiagram which describes the structure of a system by showing the system’s classes, their attributes, andthe relationships among the classes.A UML class diagram (see figure 2.7) consists of a rectangular box, which is dividedinto three sections. The fist section contents the class’s name. This nameis written centered in bold letters. The second section contents the attribute’snames of the class and the third section contents the method’s names.Class Nameattribute 1attribute 2method 1method 2Figure 2.7: A UMLClass Diagram13 Object orientated Programming is often used with the abbreviation OOP.14 The Unified Modeling Language includes a set of graphic notation techniques to create visual models of software-intensivesystems. The Unified Modeling Language is an international standard see [4], UML 2.3 was formally released in May 2010.15 This is also called Garbage Collector. In contrast to this in poor C or C++ an once allocated object has to be removedexplicitly from the memory to avoid so called memory leaks, this are blocked parts of the applications memory, which remainunaccessible until the application is closed.2.12.2011