在使用时将类名=名称空间

Question

using BusinessTask =  MyProject.WinService.Tasks.Core.BusinessTask;

I understand from the above BusinessTask class can now be used, however I'm wondering what reasons perhaps the author didn't just put:

using MyProject.WinService.Tasks.Core;

Is it perhaps to be selective on the exposure of that location since "Core" has many other classes?

Answer 1

BusinessTask may exist in several namespaces. To avoid full namespace path specification near each BusinessTask usage you can explicitly say:

using BusinessTask =  MyProject.WinService.Tasks.Core.BusinessTask;

and compiler will know that when you are using BusinessTask it should pick it up from MyProject.WinService.Tasks.Core namespace.

Here is a great example How to handle same class name in different namespaces?

Answer 2

You can use a class name alias to avoid name collisions when there is a class in another imported namespace with the same name. Even if you simply call the alias the same name as the target class, it teaches the compiler that every time you use your class name within that scope, you're referring to the one you've aliased.

See this answer here: https://softwareengineering.stackexchange.com/a/170839/144365

Answer 3

One case we faced is that we have a class name defined in two namespaces the we are referencing in the same class. So we had to use the Fully Qualified name, so the code turned out to be:

public CompanyName.ProjectName.FeatureName.ClassName SomeMethod(object param1, 
                                                              object param2, object param3)
{


}

Which was very unclear. So we replace that with

using SomeIdentifier = CompanyName.ProjectName.FeatureName;

Then the method became:

public SomeIdentifier.ClassName SomeMethod(object param1, object param2, object param3)
{


}

Having use that type like 10 times in this class, making use of that alias in the using made the code more readable.

Assume in your case you need to reference a library defining a type named 'Task'. If you need to use that inside a classing referencing System.Threading.Tasks . You need to either use the fully Qualified name System.Threading.Tasks task = .... or define an alias.