Namespaces organize the objects defined in an assembly. Assemblies can contain multiple namespaces, which can in turn contain other namespaces. Namespaces prevent ambiguity and simplify references when using large groups of objects such as class libraries.
The general namespace for ComponentOne Windows products is C1.Win. The namespace for the C1Spell component is C1.Win.C1Spell. The following code fragment shows how to declare a C1Spell component using the fully qualified name for this class:
Dim spell As C1.Win.C1Spell.C1Spell
• C#
C1.Win.C1Spell.C1Spell spell;
Namespaces address a problem sometimes known as namespace pollution, in which the developer of a class library is hampered by the use of similar names in another library. These conflicts with existing components are sometimes called name collisions.
For example, if you create a new class named C1Spell, you can use it inside your project without qualification. However, the C1Spell assembly also implements a class called C1Spell. So, if you want to use the C1Spell class in the same project, you must use a fully qualified reference to make the reference unique. If the reference is not unique, Visual Studio .NET produces an error stating that the name is ambiguous. The following code snippet demonstrates how to declare these objects:
' Define a new object based on your C1Spell class
Dim MyC1Spell as C1Spell
' Define a new C1Spell.C1Spell object
Dim Spell as C1.Win.C1Spell.C1Spell
• C#
// Define a new object based on your C1Spell class
C1Spell MyC1Spell;
// Define a new C1Spell.C1Spell object
C1.Win.C1Spell.C1Spell Spell;
Fully qualified names are object references that are prefixed with the name of the namespace where the object is defined. You can use objects defined in other projects if you create a reference to the class (by choosing Add Reference from the Project menu) and then use the fully qualified name for the object in your code.
Fully qualified names prevent naming conflicts because the compiler can always determine which object is being used. However, the names themselves can get long and cumbersome. To get around this, you can use the Imports statement (using in C#) to define an alias — an abbreviated name you can use in place of a fully qualified name. For example, the following code snippet creates aliases for two fully qualified names, and uses these aliases to define two objects:
Imports C1Spell = C1.Win.C1Spell.C1Spell
Imports MyC1Spell = MyProject.Objects.C1Spell
Dim c1 As C1Spell
Dim c2 As MyC1Spell
• C#
using C1Spell = C1.Win.C1Spell.C1Spell;
using MyC1Spell = MyProject.Objects.C1Spell;
C1Spell c1;
MyC1Spell c2;
If you use the Imports statement without an alias, you can use all the names in that namespace without qualification provided they are unique to the project.
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