Introduction
To regularly create web applications, developers must develop them in a way that is scalable, stable, and reusable. Over the past few years, object-oriented programming has become the most dominant method for creating systems that meet requirements. Using object-oriented programming can make large-scale system programs easier to read, easier to correct, and faster to upgrade.
In order to allow Visual Basic developers to benefit from object-oriented design methods and make the development of enterprise website applications easier, the next version of Visual Basic------Visual Basic .NET will support full object-oriented design. Programming functions include the implementation of continuations. With these new language features, Visual Basic .NET will bring all the features we need to develop enterprise-level applications faster and more efficiently, while maintaining the ease of use of the world's most popular development software. characteristics.
Visual Basic .NET will provide a first-class object-oriented programming language and bring many new features, such as continuation implementation, overloading and parameterized constructors. In addition, with the adjustment of modern language structures, such as structured exception handling, the code is easier to maintain, which allows developers to use concise and clear free threads to write highly scalable code. Visual Basic will provide all the language features developers need to build stable, scalable distributed Web applications. These applications will include the following new features:
New features in object-oriented programming
continuity
Overload
Parameterized constructor
Modern additional new features
free thread
Structured exception handling
Strict type checking
Shared members
Initialization function
The history of language change
The Visual Basic language has a long history of making corresponding upgrades as the basic structure of the Windows platform changes. For example, the major changes QuickBasic made to support the graphical user interface of Windows 3.0 led to the release of the first version of Visual Basic. In Visual Basic 4.0, with the shift to COM-based programming, DLLs appeared in the program structure. In addition, in Visual Basic 5.0, it began to support the creation of COM controls.
object-oriented programming
Traditional programming languages have many shortcomings. For example, its data is distributed and stored separately throughout the code segment; any structured code is not a module; because data elements are operable for any code, even if there is no Tell developers that anyone can make changes to the data, which may cause runtime errors that are extremely difficult to correct. Also, program maintenance is an extremely arduous task. It can be very difficult to change a line of code without trying to understand the impact it will have on the entire program. Finally, the trust issues caused by having programmer-level management of code and data will reduce the reuse rate of code very low.
Object-oriented programming solves all these problems. It packages the methods used to manipulate data together with the data into an object. Object data can be hidden to prevent illegal changes. In addition, an object registers a common set of methods that can be used to manipulate data. This is called encapsulation. Because the specific implementation details are separated from the actual interface, we can later change the called object program running in the background without affecting the main program and data.
Object-oriented programming enables program developers to reuse code and data through continuation. By continuing to use predefined objects, developers can create complex applications more often. Since writing new code often brings the possibility of potential bugs, reusing tested code will greatly reduce the possibility of bugs.
In order to meet all these requirements, Visual Basic .NET will provide more language features to achieve all the above-mentioned functions, making it a first-class object-oriented programming language.
continuity
One feature that everyone strongly requests Visual Basic to implement is the implementation of continuity. The development of the Internet era requires rapid assembly and reuse of large pieces. Visual Basic now supports full implementation continuation, including form continuation.
Developers can derive from an existing class using the keyword Inherits.
Class1
Function GetCustomer()
...
End Function
Class2
Inherits Class1
Function GetOrders()
...
End Function
Expressions support all common continuation-related properties. Instances of derived classes support all methods and interfaces of the base class. Of course, derived classes can also extend these methods and interfaces.
Derived classes can use the Overrides keyword to override methods defined by the base class. In order to reduce the error rate of programming, Visual Basic prevents you from overloading a function at will. Only those functions that are declared "overloadable" are allowed to be overloaded by derived classes.
Overload
Visual Basic now supports function overloading, so that programmers can use subprocedures or functions with the same name but different functions by using different parameter types.
Overloading becomes useful when your object model requires you to use similar procedure names to operate on different types of data. For example, a class that can display multiple data types can use the following display subroutine:
Overloads Sub Display (theChar As Char)
...
Overloads Sub Display (theInteger As Integer)
...
Overloads Sub Display (theDouble As Double)
Without overloading, you would have to create a unique name for each subprocedure or use Variant parameters. Overloading provides a clearer and more efficient way to handle multiple data types.
Parameterized constructor
Parameterized constructors (constructors for short) enable you to create a new instance and pass parameters to it. Constructors are critical to object-oriented programming because they enable the creator of an instance to pass creation code with custom parameters. They simplify client code by allowing you to create and initialize a new entity with a simple expression.
More New Features for a Modern Language Visual Basic .NET has added many new features that simplify the development process of writing more stable and scalable applications. These new features include free threading, structured exception handling, strict type checking and some new features such as initialization functions, shared members, etc. to improve productivity.
free line
Now, when a developer builds an application using Visual Basic, his code is synchronized. This means that the statement in the previous line must be executed before the next line of statement is entered. When developing web applications, scalability is key. Developers need tools that can process this in real time.
Free threads provide an asynchronous processing mechanism, and developers can create a new application without affecting other applications. Puke?BR>
Dim b As BackGroundWork
Dim t As Thread
Set b = New BackGroundWork()
Set t = New Thread(New ThreadStart(AddressOf b.Doit))
t.Start
End Sub
Class BackGroundWork
SubDoIt()
…
End Sub
End Class
Structured exception handling
Developing enterprise applications requires creating reusable and maintainable components. Support for error handling used to be a very good aspect of the Basic language. However, developers find that writing a reliable error handler means repeating large sections of code. Using existing On Error GoTo expressions often slows down the development and maintenance process of large applications. Its name says something: GoTo means that once an error occurs, control will be transferred to a numbered section within a subroutine. That way, when an error occurs, the program will move to a new location to execute the program just like a standard GoTo, and then jump out of the process through another GoTo or Exit. When handling several errors at the same time, when they use different combinations of Resume and Next and the execution path is not fully processed, illegal code and bugs will quickly result.
Using Try...Catch...Finally, these problems are solved. Developers can embed exception handling directly into the program, and there will be a control structure specifically used to write clearing code, whether under normal circumstances or under exceptional circumstances. This code will be executed.
SubSEH()
Try
Open "TESTFILE" For Output As #1
Write #1, CustomerInformation
Catch
Kill "TESTFILE"
Finally
Close #1
End try
End Sub
Strict type checking
The current Visual Basic language is very liberal in type declarations. In addition to using parameter passing other than by reference, the Visual Basic compiler can generate run-time casts that allow conversion of almost any type to all other types. If the data type being converted does not allow any data loss, then using a runtime cast will fail. With the new additional compilation option, Visual Basic will generate compilation errors for any type conversion that has the potential to produce a run-time error. This Strict option will cause Visual Basic to generate a compilation error to improve type safety for type conversions that might generate errors at runtime. These errors include errors that users cannot anticipate, such as automatic conversion between numbers and strings, etc.
Shared members
Shared members are data and function members that can be shared by all instances of a class. As a continuous Visual Basic application, it is necessary to share a data member or function among all instances of the class. A shared member exists independently of any specific instance of the class. A shared method is a method that is different from a regular method in that it does not implicitly pass out an instance of a class. For this reason, access to non-shared data members without the specified object is not allowed in shared methods. Public shared members can be accessed remotely and they can be post-bound to instances of the class.
Initialization function
Visual Basic .NET supports initializing variables directly on the variable definition line. The initialization function can be used anywhere, including inside control structures. This procedure-level syntax declaration of initialization function has the same effect as initializing the variable immediately after defining it. To put it another way, for example:
Dim X As Integer = 1 is the same as the following code:
Dim X As Integer X = 1 Summary Visual Basic.Net is currently one of the best object-oriented programming languages. By using Visual Basic .NET, developers can take advantage of free threads to design code with good scalability. These codes incorporate modern language features such as structured exception handling. Visual Basic will provide developers with all the language features to help design robust, scalable distributed network applications. <Enter the discussion group for discussion.