Returns true if the object is filled. If the color is null, filling uses the color of the object. Returns the color used to fill this object. The most important classes in that hierarchy are the shape classes that appear at the bottom of Figure The sections that follow provide additional background on each of the shape classes and include several simple examples that illustrate their use. As you go through the descriptions of the individual shape classes, you are likely to conclude that some of them are designed in ways that are less than ideal for introductory students.
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Object-Creation[ edit ] In this example a new object will be implemented directly derived from GObject. For simplicity, the object is named MyObject. Declaring An Object[ edit ] To create a simple non-derivable final object, two structs must be declared, the instance and the class. Boiler-Plate Code[ edit ] Since the GObject System is just a third-party library and therefore cannot make any changes to the C Language itself, creating a new object requires a lot of boiler-plate code.
This is mostly handled by the macro shown above. Defining The Object[ edit ] Before use, the newly created object must be defined, along with the instance structure. Therefore an explicit constructor must be declared for the new object.
It provides an efficient way to reuse existing code by wrapping it up into an object and then sub-classing it. The new classes are known as derived classes. Many object hieriarchies can be created using inheritance.
Inheritance is also one of the most efficient ways of abstracting code. Since C provides no keyword or operator for inheritance, a derived object is usually made by declaring the base instance and base class as a member of the derived instance and derived class respectively. Hanser describes another way of implementing classes, inheritance, instances, methods, objects, vtables, polymorphism, late binding, etc.
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