Why Does VB.Net Have Default Form Instances While C# Doesn't?

The default windows in VB.NET and C#: Differences in the two languages ​​

Introduction

Programmers who turn from VB.NET to C#often doubt why there are no windows in C#without the default instance of the window. This article explores the details of this theme, discusses the origin, differences and limitations of the default instance in VB.NET, and the reasons for the lack of default instances in C#.

The origin of the default instance

In vb.net, the window is unique in the name space through its name attribute. This name attribute is also convenient for the default instance of the window. This function allows developers to directly use its name to access the window, even if there is no explicit creation instance. For example, in VB.NET, you can use to display the window without the need to instantiate the object first.

Implementation differences Form1.Show() Form1

In C#, the window will not automatically obtain the default instance. When you want to display the window, you must create an instance of the window class, and then call the

method. This is because C#follows more class -oriented objects, where the instances of the class are different from the class itself. The generated IL code

Show() Interestingly, the IL code generated by the two languages ​​reveals deeper differences. In VB.NET, the default instance is expressed as a static method on the window class. On the other hand, in C#, the

method is an instance method. This difference enhances such a fact: in C#, the window is considered an instance of the class, not the class itself.

Advantages and limitations

The default instance mechanism in vb.net provides a shortcut for programmers who want to directly access the window. It is also in line with the expectations of VB6 programmers who are accustomed to working without explicit instances. However, this convenience is costly. The method generated by static can not accept the parameters, making it uncomfortable with the instance method.

Show() The equivalent method in c#

Although C#itself does not support the default instance of the window, it can simulate this behavior by creating a global static attribute that returns a window -class instance. However, this method is not concise enough and requires additional model code.

Conclusion

Show()

The existence of the default instance of the window in vb.net is a historical product, which reflects the evolution of the language from its origin of Basic -based language to modern object -oriented language. On the other hand, C#uses a more pure object -oriented method, where the windows are strictly considered to be an instance of the class, and must be explicitly instantiated. Understanding the differences and limitations of these methods is essential for programmers who use these two languages.

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