.NET/ASP.NET/C#/VB.NET PDF Document SDK

One of the most interesting object-oriented programming concepts is inheritance, as it allows you to generate a taxonomy of classes and objects. If you consider all living things as a class called LivingThing (see Figure 6-1), under that class you could have (and let s keep this simple, biologists!) Plant and Animal classes. Under Animal you d have Mammal, Fish, Amphibian, and so forth. Digging into Mammal, you could work through Primate and Human. A Human is a living thing, a Human is an Animal, a Human is a Mammal, and so forth, but each level down is more specific and targeted than that above it. This is class inheritance in action! The same system applied to the Shape example where Triangle and Square inherited directly from Shape.

winforms pdf 417 reader, winforms qr code reader, winforms upc-a reader, winforms data matrix reader, winforms gs1 128, winforms ean 13 reader, itextsharp remove text from pdf c#, find and replace text in pdf using itextsharp c#, winforms code 39 reader, itextsharp remove text from pdf c#,

1

The benefit of inheritance is that classes lower down the hierarchy get the features of those higher up, but can also add specific features of their own. The basic all living things class is so generic that the only functionality you could give to it is a basic living or dead method. However, at the animal level, you could add methods such as eat, excrete, or breathe. At the human level you d inherit all this functionality but be able to add human methods and qualities such as sing, dance, and love. Ruby s inheritance features are similarly simple. Any class can inherit the features and functionality of another class, but a class can only inherit from a single other class. Some other languages support multiple inheritance, a feature that allows classes to inherit features from multiple classes, but Ruby doesn t support this. Multiple inheritance can cause some confusing situations for instance, classes could inherit from one another in an endless loop and the efficacy of multiple inheritance is debatable. Let s look at how inheritance works in code form:

class ParentClass def method1 puts "Hello from method1 in the parent class" end def method2 puts "Hello from method2 in the parent class" end end class ChildClass < ParentClass def method2 puts "Hello from method2 in the child class" end end my_object = ChildClass.new my_object.method1

Each line in a block must be indented by the same amount. The following is pseudocode (not real Python code) but shows how the indenting works: this is a line this is another line: this is another block continuing the same block the last line of this block phew, there we escaped the inner block

In an entertaining ctional story, the main character is someone an audience observes from a distance. But in a non ction presentation, making the audience the center of the action can dramatically increase the involvement any audience feels. You ll learn how you can always make your audience the main character of your presentation story when you plan your rst ve slides in 4. In keeping with classical storytelling form, Mark s next step would be to present the main characters with a problem that they would have to face.

First you create the ParentClass with two methods, method1 and method2. Then you create ChildClass and make it inherit from ParentClass using the ChildClass < ParentClass notation. Last, you create an object instance of ChildClass and call its method1 and method2 methods. The first result demonstrates inheritance perfectly. ChildClass has no method1 of its own, but because it has inherited from ParentClass, and ParentClass has a method1, it uses it. However, in the second case, ChildClass already has a method2 method, so the method2 method supplied by the parent class is ignored. In many cases, this is ideal behavior, as it allows your more specific classes to override behavior provided by more general classes. However, in some situations you might want a child method to call an inherited method and do something with the result. Consider some basic classes that represent different types of people:

class Person def initialize(name) @name = name end def name return @name end end class Doctor < Person def name "Dr. " + super end end