在2个.NET程序集中使用相同名称和命名空间的类型

Question

Out of curiosity, I've created 2 assemblies which both have a class ( Class1 ) with the exact same namespace ( Library1 ). I then create another client referencing those 2 assemblies and try to create an instance of Class1 .

The compiler, not surprisingly, gives me a compile-error about the ambiguous reference. Is there any way to explicitly specify the type in the assembly I want to use to avoid the ambiguity?

Note: I know this rarely, if ever at all, happens in practice. It's just a question out of curiosity about language feature.

Answer 1

I think you should use an extern alias to wrap the assembly namespaces outside of the Global namespace. Here's how:

1. In the project that references the 2 assemblies, select one of them under References, and in the Properties window change the Aliases value from global to, say, global, Library1a .

2. Do the same for the the other reference, but give it a different alias-- let's go with global, Library1b for our example.

3. Insert extern alias Library1a; and/or extern alias Library1b; as the first 2 lines of any classes that consume the assemblies.

4. When accessing ambiguous members, qualify the namespace with Library1a. or Library1b. . Examples: Library1a.Library1.Class1... Library1b.Library1.Class1...

Answer 2

It happens in practice and is a real pain, the external alias can't always solve the problem. Here's one example of where it's an issue Duplicate Namepsaces .