C＃：声明要使用的数据类型的常量变量

Question

Is it possible somehow to define a constant that says what datatype to use for certain variables, similar to generics? So in a certain class I would have something like the following:

MYTYPE = System.String;

// some other code here

MYTYPE myVariable = "Hello";

From the principle it should do the same as generics but I don't want to write the datatype every time the constructor for this class is called. It should simply guarantee that for two (or more) variables the same datatype is used.

Answer 1

Well, you can use a using directive:

using MYTYPE = System.String;

However, that isn't really like a typedef - in particular, this code is now perfectly valid:

MYTYPE x = "hello";
string y = "there";
x = y;

The compiler knows they're still the same type.

It's not really clear what you're trying to achieve, particularly here:

I don't want to write the datatype every time the constructor for this class is called.

What do you mean?

Note that using directives are specific to a source file, not to a whole project.

Answer 2

You can do that with a using alias:

using MyType = System.String;

however, only on a per-file basis. Frankly, it is useful for making a short alias to some complex composite generic type (I'm thinking of "Owin" etc), but other than that, generics are more versatile.

Answer 3

You could use an alias:

using System;
using MYTYPE = System.String;

class Program
{
    static void Main()
    {
        MYTYPE f = "Hello";
        Console.WriteLine(f);
    }
}

Answer 4

Yes, with a using alias directive .

edit: beaten by a couple of seconds..