At the same time, it's convenient to formally establish this relationship so that the different objects can be used in similar contexts. There are some cases when you have two objects (or classes) that are related and that perform the same tasks, but they both do it in such a fundamentally different way that establishing the class/subclass relationship doesn't really buy you anything. Simply put, you don't have to write any new methods for the subclass to get the functionality resident in the superclass. The benefit to this, so the story goes, is that it enables code reuse. Although the subclass may optionally reimplement or override a method from the parent class, it doesn't have to reimplement any method unless it wants to modify what that method does. Nevertheless, when one class is a subclass of another, it shares all the same members with the parent class. Other languages, such as Objective-C, refer to a similar concept as a protocol. ![]() In REALbasic, an interface is used much in the same way that the term is used with Java. This is also one of those areas where the term is used differently in different programming languages. Interfaces are another means by which you encapsulate your program. When talking about Interfaces, you say that a class implements a particular Interface. With subclassing, one class can be a subclass of another. Interfaces are an alternative to subclassing. Interfaces and Component-Oriented Programming In this section I will review some relatively more advanced programming techniques you can use to extend the functionality of your REALbasic classes. When you are finished writing text to the file, call the TextOutputStream's Close method to close the stream to the file making the file available to be opened again.REALbasic Cross-Platform Application Development This is controlled by the TextOutputstream's Delimiter property which can be changed to any other character. The WriteLine method, by default, adds a carriage return to the end of each line. You then use the WriteLine method of the TextOutputStream class to write the text to the text file. These methods are functions that return a "stream" that carries the text from your app to the text file. If you are creating a new text file or overwriting an existing text file, use the Create shared method of the TextOutputStream class. ![]() Once you have a FolderItem that represents the text file you wish to open and write to, you open the file using the Append shared method of the TextOutputStream class. It assumes that the valid text file types have been defined in a File Type Set called TextTypes: This code lets the user choose a text file using the Open-file dialog box and displays the text in a TextArea. When you are finished reading text from the file, call the TextInputStream's Close method to close the stream to the file, making the file available to be opened again. This property will be True when the end of the file has been reached. As you read text, you can determine if you have reached the end of the file by checking the TextInputStream's EndOfFile property. The ReadLine method returns the next line of text (the text after the last character read but before the next end of line character). ![]() The TextInputStream.ReadAll method returns all the text from the file (via the TextInputStream) as a String. The TextInputStream keeps track of the last position in the file you read from. You then use ReadAll or ReadLine methods of the TextInputStream to get the text from the text file. This is a special class of object designed specifically for reading text from text files. This method is a function that returns a “stream” that carries the text from the text file to your application. Once you have a FolderItem that represents an existing text file you wish to open, you open the file using the Open shared method of the TextInputStream class. Reporting bugs and making feature requests.Reading and writing data in JSON format.Accessing the file system via the FolderItem class.
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