This lets you define a namespace out of the root namespace of your project. The root namespace can lead to unexpected concatenations of namespace names. If you make reference to namespaces defined outside your project, the Visual Basic compiler can construe them as nested namespaces in the root namespace. In such a case, the compiler does not recognize any types that have been already defined in the external namespaces.
To avoid this, either set your root namespace to a null value as described in "Root Namespace," or use the Global keyword to access elements of external namespaces. You cannot apply attributes to a namespace. An attribute contributes information to the assembly's metadata, which is not meaningful for source classifiers such as namespaces. You cannot apply any access or procedure modifiers, or any other modifiers, to a namespace.
Because it is not a type, these modifiers are not meaningful. The following example declares multiple nested namespaces on a single line, and it is equivalent to the previous example.
The following example defines the skeleton of a new generic list class and adds it to the System. Generic namespace. Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services.
Privacy policy. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Is this page helpful? Yes No. In order to be imported, the namespace must be in a referenced component.
What does a namespace do? A namespace is a declarative region that provides a scope to the identifiers the names of types, functions, variables, etc inside it. Namespaces are used to organize code into logical groups and to prevent name collisions that can occur especially when your code base includes multiple libraries.
What is namespace in Visual Basic? Namespaces are similar in concept to a folder in a computer file system. Like folders, namespaces enable classes to have a unique name or we can say that it is a logical naming scheme for grouping related types.
Every project in C or VB. NET starts with a Namespace, by default the same name as the name of the project. In C , namespaces are used to logically arrange classes, structs, interfaces, enums and delegates. The namespaces in C can be nested. That means one namespace can contain other namespaces also. In computing, a namespace is a set of signs names that are used to identify and refer to objects of various kinds. Prominent examples for namespaces include file systems, which assign names to files.
Some programming languages organize their variables and subroutines in namespaces. The compiler may detect this and not compile the program. In the worst case, the program may still compile but call the wrong function, since we never specified to which namespace the identifier belonged. The std namespace is huge. Classes are data types. They are an expanded concept of structures, they can contain data members, but they can also contain functions as members whereas a namespace is simply an abstract way of grouping items together.
A namespace cannot be created as an object; think of it more as a naming convention. It is because computer needs to know the code for the cout, cin functionalities and it needs to know which namespace they are defined. Assembly defines the name of the. Namespace is used in order to avoid conflict of user defined classes. Namespaces that you create for your own declarations are called user-defined namespaces.
Namespace identifiers are typically non-capitalized. Net Framework belongs to the System Namespace. The "system" Namespace has built-in VB functionality and all other Namespaces are based on this "system" Namespace.
We can access a member of a Namespace by using a dot. The members of a Namespace are the variables, procedures and classes that are defined within a Namespace. To access the member of a namespace in a desired location type the name of the namespace followed by the dot or period operator followed by the desired member of the namespace.
The following program shows accessing the element of a namespace in various ways. Nesting a Namespace. Nesting a Namespace means create a namespace inside a namespace. A good way to organize namespaces is to put them in a hierarchal order, i. Note: You can not have two classes with the same name in the same scope.
In other words, class overloading is not allowed. Aliases are created when we have nested Namespaces. It is easy to access the members of the namespaces by the alias. An alias is a shortcut for a nested namespace with a shorter label. An alias of a namespace is created with the help of the "imports" keyword. Aliasing is useful when we are working with a large project.
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